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ATTACHMENT A 



Cryogenic 
Engineering 




Edited by 
B.A.HANDS 



Cryogenic Engineering 



Edited by 



B. A. Hands 

Department of Engineering Science, University of Oxford 
and St. Hilda's College, Oxford, England 



1986 




Academic Press 

Harcourt Brace Jouanouich, Publishers 
London Orlando New York San Diego Austin 
Boston Tokyo Sydney Toronto 



ACADEMIC PRESS INC. (LONDON) LTD. 
24/28 Oval Road, London NW1 7DX 

United States Edition published by 
ACADEMIC PRESS, INC. 
Orlando, Florida 32887 



Copyright © 1986 by 
Academic Press Inc. (London) Ltd. 

All rights reserved. No part of this book may be reproduced 
or transmitted in any form or by any means, electronic or 
mechanical, including photocopy, recording, or any 
information storage and retrieval system without permission 
in writing from the publishers 



British Library Cataloguing in Publication Data 

Cryogenic engineering. 
1. Low temperature engineering 
I. Hands, B.A. 
621.5'9 TP482 

ISBN 0-12-322990-1 
ISBN 0-12-322991-X (Pbk) 



Computer typeset and printed by 
Page Bros (Norwich) Ltd 



C. A. Bail 
eering S 
and FelJ 

R. A. Byrii 
Formed 
Californ 

D. Dew-Hi 
versity c 
versity C 

D. Evans 
OQX, Ei 

E. J.Gregc 
Fordhou 

B. A. Hant 
eering S< 
and G.E 

G. Kraffl 
Karlsrah 

J. T. Moif 
OX11 oc 

N. Nambud 
Bombay 
Engineer 

B. W. Rid 
inghamsh 

J. M. Robei 
Establish: 

H. Sixsmitl 
Hampshii 

W. L. Swi) 

Hampshii 
W. J. Tallis 

Science, 1 
R. M. Thoi 

Chemical: 
T. J. Webst 

England. 



Contributors 



C. A. Bailey University Lecturer, Cryogenics Laboratory, Department of Engin- 
eering Science, University of Oxford, Parks Road, Oxford OX1 3PJ, England 
and Fellow of Keble College, Oxford 

R. A. Byrns Consultant, 2457 Marin Avenue, Berkeley, California 94708, U.S.A. 
Formerly Staff Senior Scientist, Lawrence Berkeley Laboratory, University of 
California, Berkeley, California 94720, U.S.A. 

D. Dew-Hughes University Lecturer, Department of Engineering Science, Uni- 
versity of Oxford, Parks Road, Oxford 0X1 3PJ, England and Fellow of Uni- 
versity College, Oxford 

D. Evans Rutherford Appleton Laboratory, Chilton, Didcot, Oxfordshire OX11 
OQX, England 

E. J. Gregory Chief Process Engineer, Marston-Palmer Limited, Wobaston Road, 
Fordhouses, Wolverhampton WV10 6QJ, England 

B. A. Hands Research Associate, Cryogenics Laboratory, Department of Engin- 
eering Science, University of Oxford, Parks Road, Oxford OX1 3PJ, England 
and G.E.C. Lecturer in Engineering, St. Hilda's College, Oxford 

G. Krafft Koordinationstelle Technologietransfer, Kernforschungszentrum 
Karlsruhe GmbH, Postfach 3640, D-7500 Karlsruhe 1, West Germany 

J. T. Morgan Rutherford Appleton Laboratory, Chilton, Didcot, Oxfordshire 
OX11 OQX, England 

N. Nambudripad Tata Institute of Fundamental Research, Homi Bhabha Road, 
Bombay 400 005, India. Formerly of the Cryogenics Laboratory, Department of 
Engineering Science, University of Oxford 

B. W. Ricketson Cryogenic Calibrations Limited, Pitchcott, Aylesbury Buck- 
inghamshire HP22 4HT, England 

J. M. Robertson Heat Transfer and Fluid Flow Service, Atomic Energy Research 
Establishment, Harwell, Oxfordshire OX11 ORA, England 

H. Sixsmith Creare Inc., PO Box 71, Great Hollow Road, Hanover New 
Hampshire 03755, U.S.A. 

W. L. Swift Creare Inc., PO Box 71, Great Hollow Road, Hanover New 

Hampshire 03755, U.S.A. 
W. J. Tallis Design Engineer, Cryogenics Laboratory, Department of Engineering 

Science, University of Oxford, Parks Road, Oxford OX1 3PJ, England 
R. M. Thorogood Director, Cryogenic Research Programs, Air Products and 

Chemicals Inc., PO Box 538, Allentown, Pennsylvania 18105, U.S.A. 
T. J. Webster Consultant, 38 Parkland Grove, Ashford, Middlesex TW15 2JR, 

England. Formerly Safety Manager, British Oxygen Company Ltd., England ' 



Preface 



The 1960s saw great activity in the field of cryogenic engineering, stimulated 
particularly by the American space effort and by developments in superconductivity. 
As a result, a number of books on cryogenic engineering in general were published. 
Since then, most volumes have concentrated on a particular aspect of the subject, 
rather than attempting a comprehensive review. In view of the steady, if unspec- 
tacular, advances made since that time, it seems opportune to attempt a new 
account of the basic science and of the engineering methods employed. 

Cryogenic engineering covers a wide spectrum of disciplines, in traditional terms 
embracing much of electrical, mechanical and chemical engineering, its dis- 
tinguishing feature being the use of temperatures well below ambient. In order to 
produce a volume of reasonable length, it was decided to assume that the reader 
should have knowledge appropriate to that of a final-year or graduate engineer or 
physicist. Further, since much of the body of knowledge of engineering at room- 
temperature can be applied directly to cryogenic problems, reference in such 
cases is made to standard textbooks, although since this book is biased towards 
engineering, the physicist may need to consult rather more of them than the 
engineer. 

It was also decided, again on the grounds of overall length, to restrict the account 
of superconductivity. The design of superconducting magnets is very largely an 
electrical engineering problem, the cryogenic design, apart from training problems 
and stabilisation, being relatively straightforward. Further, the monograph 
"Superconducting Magnets" by M. N. Wilson (Oxford University Press, 1985) 
treats the subject comprehensively, and is required reading for anyone with other 
than a superficial interest in magnet design. Thus, the coverage of this topic is 
deliberately brief. 

There are some other deliberate omissions, also. In particular, an account of 
refrigeration using hydrogen and neon is omitted, on the grounds that the techniques 
involved are broadly the same as those used for helium. Similarly, the particular 
problems involved with cryogenics in space are given only passing mention, since 
most of the design principles involved are also applicable to earth-based equipment. 
There is no attempt to provide complete property data; general trends are indicated , 
and, it is hoped, enough references for the reader to locate detailed data as 
necessary. However, since the book is intended for potential (and practising) 
cryogenic engineers, details of practical methods and current practices have been 
included. 



PREFACE 



The production of this book has been a co-operative effort, and I thank the 
authors for their tolerance of the editor's quirks. I should like to acknowldge those 
who have read parts of my own contributions and assisted with the provision of 
information, photographs and diagrams, particularly Dr A. Acton, Dr V D Arp 
Mr R. J. Allam, Dr C. A. Bailey, Dr M. L. Christie, Dr. G. Davey Prof G B 
Donaldson, Mr R. Harper, Dr D. B. R. Kenning, Dr R. D. McCarty, Dr W 
Obert, Dr. C. Ruiz, DrL. Solymar and Dr. R. M. Thorogood. Acknowledgements 
and sources for diagrams and photographs are given as appropriate in the text I 
am most grateful to the organisations which supplied these and gave permission for 
their use. I am indebted to Johanne Beaulieu for preparing much of the text to 
Mrs Judith Takacs for drawing the diagrams with her usual patience and skill and 
to Mrs Stella Seddon for preparing the index. Finally, gratitude is due to my family 
for their tolerance, and for foregoing the use of the dining table for many months. 

0rf ° rd > 1985 B. A. Hands 

In the tables of data, a dash indicates that information was not available. 



1.1 Introd 

1.2 The C 

1.3 Featui 

1.5 Air Se 

1.9 Cryog. 

1.10 Cryog. 

1.11 Medic 

1.12 Cry op 
.1.13 Instnu 

Refere 

Gener 
BibliOj 
Non-si 



2.1 Introdu 

2.2 Proper! 

2.3 Hydrog 

2.4 Helium 

2.5 Equatic 



PREFACE 



id I thank the 
nowldge those 
ie provision of 
Dr V. D. Arp, 
ly, Prof G. B. 
Carty, Dr W. 
owledgements 
: in the text; I 
permission for 
of the text, to 
and skill, and 
e to my family 
many months. 

A. Hands 

jbk. 



Contents 



Contributors 



1. A Survey of Cryogenic Engineering 
B. A. Hands 



1.1 Introduction j 

1.2 The Cryogenic Temperature Range 2 

1.3 Features of Cryogenic Engineering 3 

1.4 Liquefied Natural Gas (LNG) 6 

1.5 Air Separation 10 

1.6 Liquid Hydrogen 15 

1.7 Liquid Helium jg 

1.8 Superconducting Magnets and Machinery 19 

1.9 Cryogenic Electronics 26 

1.10 Cryogenics in Space 29 

1.11 Medical and Biological Applications 29 

1.12 Cryopumping 30 

1.13 Instrumentation 33 
References 34 
Journals . 35 
General Bibliography 36 
Bibliography of Specific Topics 36 
Non-specialist Reading 37 



2. Properties of the Cryogenic Fluids 
B. A. Hands 

39 
40 
43 
46 
50 



2.1 Introduction 

2.2 Property Data 

2.3 Hydrogen 

2.4 Helium 

2.5 Equations of State 



2.6 The Two-phase Region 

2.7 Computer Packages 

2.8 Approximate Equations 

2.9 Properties of Mixtures 
References 

Sources of Data 



3. Cryogenic Safety 
T. J. Webster 

3.1 Introduction 

3.2 Organisation for Safety 

3.3 Relationship between Fluid Properties and Safety 

3.4 First Aid 

3.5 Combustion 

3.6 Oxygen Hazards 

3.7 Unexpected Hazards 

3.8 Fluorine Safety 
Bibliography 



4. Thermal Design 
C. A. Bailey and B. A. Hands 



1 Conservation of Energy Considerations 

2 General Energy Requirements 

3 Specific Heat 

4 Thermal Contraction 

5 Thermal Conductivity of Solids 

6 Conduction through Gases 

7 Radiative Heat Transfer 

8 Thermal Insulations 

9 Applications to Design 
References 
Bibliography 



5. Fluid Dynamics 
B. A. Hands 



5.1 Introduction 

5.2 Pressure Drop Calculations 

5.3 Single-phase Pressure Drop 

5.4 Characteristics of Two-phase 

5.5 Two-phase Pressure Drop 

5.6 Critical (Choked) Flow 

5.7 Cooldown Behaviour 

5.8 Introduction to Instabilities 



9.4 Magnetoresistance 

9.5 Superconductivity 

9.6 Theories of Superconductivity 

9.7 Flux-pinning and Critical Current Density 

9.8 Conductor Stability 

9.9 Stress Effects 

9.10 Commercial Superconductors 
Bibliography 



10. Mechanical Design with Metals 



10.1 Introduction 

10.2 Elastic Moduli 

10.3 Plastic Behaviour 

10.4 Fracture Behaviour 

10.5 Fatigue Behaviour 

10.6 Aluminium Alloys 

10.7 Stainless Steels 

10.8 Nickel-Iron Alloys 

10.9 Titanium Alloys 

10.10 Copper Alloys 

10.11 General Discussion 
References 
Bibliography 



11. Design with Non-metallic Materials 
D. Evans and J. T. Morgan 

11.1 Introduction 

11.2 Mechanical Properties of Polymers and their Relation to Structure 

11.3 Thermal Contraction 

11.4 Thermal Conductivity 
Bibliography 



12. Construction and Assembly Methods 
W. J. Tallis 



12.1 General Design Considerations 

12.2 Permanent Joints 

12.3 Demountable Joints 

12.4 General Comments 



CONTENTS 



CONTENTS 



13. Principles of Refrigeration, Liquefaction and Gas Separation 
C. A. Bailey and B. A. Hands 

13.1 Refrigeration 

13.2 Liquefaction 

13.3 Cooling Methods 

13.4 Simple Cycles 

13.5 Irreversibility 

13.6 Second Law Violations 

13.7 Compound Cycles 

13.8 The Separation of Gases 

13.9 Principles of Distillation 

13.10 The Single Column Linde System '■ 

13.11 The Double Column ; 
References 



14. Cryogenic Turbines and Pumps 
H. Sixsmith and W. L. Swift 



14.1 Introduction 

14.2 Turboexpander Design 

14.3 Gas Bearings 

14.4 Protective Devices 

14.5 Turbine Performance 

14.6 Pumps 

14.7 Conclusions 
References 



15. Large Helium Refrigeration and Liquefaction Systems 



271 
276 


R. A. Byrns 




285 


15.1 Specification of Heat Load and Capacity 


357 


289 


15.2 Design of J-T Stage 


360 


292 


15.3 The Claude Cycle 


362 




15.4 Design and Optimisation 


364 




15.5 Compressors 


366 




15.6 Heat Exchangers 


368 




15.7 Expanders 


369 




15.8 Control, Instrumentation, Purity and Gas Management 


371 




15.9 Distribution and Cooling Methods 


372 


293 


15.10 Large Helium Plants 


375 


15.11 Large Purification Liquefiers 


375 


295 


15.12 The 1500 W Refrigerator 


376 


302 


15.13 Lawrence Livermore National Laboratory (3000 W) System 


379 


309 


15.14 Fermi Natiorial Accelerator Laboratory (23 kW) System 


381 



15.15 Brookhaven 24.8 kW Refrigerati 

15.16 Refrigeration Equipment Cost 



16. Large Gas Separation and Liquefaction Plants 
R. M. Thorogood 



16.1 Introduction 

16.2 Cryogenic Air Separation Processes 

16.3 Natural Gas Processes 

16.4 Natural Gas Liquefaction Processes 

16.5 Equipment for Large Air Separation ] 

16.6 Equipment for Natural Gas Plants 

16.7 Operation and Safety 
Acknowledgements 
References 



17. Small Refrigerators 
N. Nambudripad 



17.1 Introduction 

17.2 The Stirling Refrigerator 

17.3 The Gifford-McMahon Refrigerator 

17.4 The Pulse-tube Refrigerator 

17.5 The Vuilleumier Refrigerator 

17.6 Losses in Regenerative Mechanical Coolers 

17.7 Regenerators 

17.8 Magnetic Refrigeration 
References 



18. Thermometry 
B. W. Ricketson 



18.1 Introduction 

18.2 Temperature and Accuracy 

18.3 Criteria for Choosing a Sensor 

18.4 Sensors 

18.5 Thermal Anchorage for Electrical Leads 

18.6 Measurement 

18.7 Temperature from the Measurement 

18.8 Conclusion 
References 



Appendix 



Symbols Used 




Absorber Vessel 

Containing 



1 

A Survey of Cryogenic Engineering 



B. A. HANDS 



1.1 Introduction 

1.2 The Cryogenic Temperature Range 

1.3 Features of Cryogenic Engineering 

1.4 Liquefied Natural Gas (LNG) 

1.5 Air Separation 

1.6 Liquid Hydrogen 

1.7 Liquid Helium 

1.8 Superconducting Magnets and Machinery 

1.9 Cryogenic Electronics 

1.10 Cryogenics in Space 

1.11 Medical and Biological Applications 

1.12 Cryopumping 

1.13 Instrumentation 
References 
Journals 

General Bibliography 
Bibliography of Specific Topics 
Non-specialist Reading 



Most of this book is concerned with an outline of the theory and practice 
of cryogenic engineering. It has not been possible within a volume of 
reasonable size to explore every aspect in detail, nor has it been possible 
to give a detailed account of all the applications of cryogenics. This chapter 
is intended to give an impression of the wide range of cryogenic engineering. 
After a discussion of the meaning of cryogenics, the chapter covers the 
uses of the commoner cryogenic liquids (natural gas, oxygen, nitrogen, 
hydrogen and helium), and then deals with superconductivity and cryo- 



B. A. HANDS 

pumping. The chapter concludes with a brief outline of cryogenic 
instrumentation. 



1.2 The Cryogenic Temperature Range 

The 1960s were a decade which saw a rapid expansion both in low- 
temperature physics and in the commercial exploitation of low-temperature 
techniques. Towards the end of this period, a need was felt for the stand- 
ardisation of low-temperature terminology, and, on the initiative of Pro- 
fessor Nicholas Kurti, the Comite d'etude des termes techniques francais 
organised a meeting in 1969, at which -was formed a small international 
committee to consider the terminology of low temperatures, remembering 
the necessity of unambiguous translation between English and French, and 
paying due regard to current practice in the United States. As an example 
of the confusion which then existed, temperature levels in Britain were, by 
some people, referred to as 'low' (below 0°C), 'very low' (around 100 K), 
'deep low' (around 4K) and 'ultra low' (less than 0.3 K), although the 
French had only two terms 'basse' and 'tres basse'. It was never clear how 
the British users of this terminology would refer to temperatures in the 
microkelvin region! 

The working group, with members from six countries, made its re- 
commendations in 1971 [1.1], and these have largely been accepted by the 
scientific community. 'Cryogenics' and the corresponding prefix 'cryo' were 
to refer to 'all phenomena, processes, techniques or apparatus occurring 
or used at temperatures below 120 K' approximately, that is, around or 
below the normal boiling point of liquefied natural gas. It was recognised, 
however, that some inconsistencies were unavoidable, in particular the use, 
on historical grounds, of the terms cryohydrate, cryoscopy, cryochemistry 
and the French cryodessication, all of which refer to temperatures well 
above 120 K; and, because they use cryogenic fluids and techniques, cryo- 
surgery, cryomedicine and cryobiology. Otherwise, the temperature range 
between 120 K and 0°C is covered by 'refrigeration' technology. 

The scientific community has, on the whole, adhered to these proposals, 
but they have not been rigidly adopted by industry, where the technology 
of handling liquid ethylene (at around 150 K) is, with some justification on 
the grounds of the equipment used, included in the cryogenic domain, and 
'cryogenic' is also used, with less justification, to describe equipment 
designed for use at still higher temperatures. However, since all fluids 
and materials used in cryogenics must at some time be brought to room 
temperature, properties and processes in the temperature range up to room 
temperature cannot be ignored. 



1. A SURVEY OF CR1 

In this book, we 
engineering' to refe 
most widely used liq 
liquefied natural gas 
liquid hydrogen (LI 
importance of hydro 
range, the producti 
regarded as 'physics' 
at present to experii 
demagnetisation anc 
be covered in this vc 



1.3 Features of Cryo 

It is worth considerii 
'ordinary' (or room t 
that the properties o 
a particular mystiqu 
accepted that, in fac 
behave similarly to c 
ability to recognise an 
the use of low temp 
different from that re 
ment of design criter 
with identification c 
methods to achieve 
should, therefore, be 
in its own right. 

There are, howeve 
eering temperature n 
fluidity— the ability o 
The superfluid state h 
etical physicists for m 
has been achieved. I 
because of the very h 

The other phenome 
of electrical resistan< 
different for each met; 

* According to [1.1], the 
wide acceptance. 



A. HANDS 
cryogenic 



i in low- 
nperature 
the stand- 
'e of Pro- 
:s francais 
;rnational 
tembering 
ench, and 
1 example 
i were, by 
id 100 K), 
lough the 
clear how 
res in the 

de its re- 
ted by the 
;ryo' were 
occurring 
around or 
jcognised, 
arthe use, 
•chemistry 
tures well 
ues, cryo- 
ture range 

proposals, 
echnology 
ication on 
main, and 
squipment 
; all fluids 
t to room 
ip to room 



1. A SURVEY OF CRYOGENIC ENGINEERING 3 

In this book, we follow the 1971 recommendation and take 'cryogenic 
engineering' to refer to the temperature range below about 120 K. The 
most widely used liquids, in order of descending normal boiling point, are 
liquefied natural gas (LNG), liquid oxygen (LOX), liquid nitrogen (LIN), 
liquid hydrogen (LH 2 ) and liquid helium (LHe), although at present the 
importance of hydrogen has declined. At the lower end of the temperature 
range, the production of temperatures less than about 1.5 K may be 
regarded as 'physics' rather than 'engineering', since their use is restricted 
at present to experimental work. Therefore, techniques such as adiabatic 
demagnetisation and the use of the light isotope of helium (He 3 ) will not 
be covered in this volume. 



1.3 Features of Cryogenic Engineering 

It is worth considering at this stage the differences between cryogenic and 
'ordinary' (or room temperature) engineering. For a long time, it was felt 
that the properties of cryogenic fluids were in some way peculiar, so that 
a particular mystique arose around this area of engineering. It is now 
accepted that, in fact, cryogens (with the exception of superfluid helium) 
behave similarly to other fluids, and that the art of cryogenics lies in the 
ability to recognise and cater for the particular problems which arise through 
the use of low temperatures per se. This requirement is, of course, no 
different from that required in any other branch of engineering: an assess- 
ment of design criteria and possible causes of equipment failure, together 
with identification of the best techniques, materials and construction 
methods to achieve safe, efficient and reliable operation. Cryogenics 
should, therefore, be regarded more as a special art rather than as a subject 
in its own right. 

There are, however, two phenomena peculiar to the cryogenic engin- 
eering temperature range which merit special consideration. One is super- 
fluidity — the ability of liquid helium to behave as if it has zero viscosity. 
The superfluid state has been investigated by both experimental and theor- 
etical physicists for many years, and a deep understanding of its behaviour 
has been achieved. From the engineer's point of view, it is of interest 
because of the very high rates of heat transfer which can be attained. 

The other phenomenon is that of superconductivity,* the complete loss 
of electrical resistance below some well-defined temperature which is 
different for each metal. Superconductivity is of increasing technical import- 

• According to [1.1], the proper term is superconduction, but this word has never achieved 
wide acceptance. 



application to^ea^e^fafenri^ StaWe ma8netic fieIds > «>d its 
1962, the discovery of t^SS^f 1S ^ eXtenSivdy Studied - I" 
ofsupero ) nduc tl n g elec7ronlTX 

new range 

For instance, to extract 1 J of hSt re^M* abso,ute te mperature. 
of work, while to extract Tj ^Tk *- * ??K ^ uires "bout 3.7 J 
practice, of course, reversibility cannot beTh"* 68 J ° f Work " ^ 

required is somewhatlarger byafew ten , f 3nd the Work act »ally 

temperatures, to a factor rt^^^ 1 ?^^**^ 

^^^^^^^ ««- -wards the end of 
•n Geneva, Switzerland, and Z tZlc^uT ^7^' by Raoul Picte t 
France.* Each used a d fferent teSnl i * ^"on-sur-Seine in 
470 bars to about 140 K ST techni que. Octet's was to cool oxygen at 
carbon crfj^ 

through a valve, and saw a Surl nf . the ° X ^ en to e **pe 

jet. Cailletet, on the oaJS^SX ^ ^ fa the resuIt 4 
liquid sulphur dioxide, and then DerrSSL to ° n,y ~ 29 ° C u ^g 

a mist of droplets in hi gJa J ^ vesseMt ^1 h" eXpansion to fo ™ 

Pictefs method of 'casi^oS foB^^^r^ l ° ° bS6rVe that 
is still used in many designs rfS^Tan^?^™" CXpansi ° n 
in association with cateiJal. wlr S|SS a,ld ^ ' USUal,v 

paved the way for the Uq2c££^£* St0r "! for lon g Periods and 
mention, theliquidswe/estore^ ^zntLfnn g andhe,ium - Until Dewar's 
vessels, each containing in turn a SnL . T:° fanUmberofco ^entric 
vacuum insulated, glasf flasks n OW ™ e 
.Thermos'; in the scientific comm I i^^L t ?, the «f neral P u Wic as a 
•s also used for small storage vesTel "of n ^ ,S preferred and 
. DevelopmentsduringthenexttwoHe^ 

m France and Linde in German! develon apaCe ' with 

and fractional distillation of Z to T/ teChn ^ Ues for the Lquefaction 
to produce oxygen and nitrogen, and 

* Which scientist was first is of no concern to 
has been drscussed recently by Kurti ?i 2] 



' S here> nor is ,he ei >suing controversy, which 



B. A. HANDS 1. A SURVEY OF CRYOGENIC ENGINEERING 5 

;lds, and its forming companies which are still in the forefront of cryogenic engineering 

y studied. In today to market their inventions. Finally, in 1908, helium, the last of 

a new range the 'permanent' gases, was liquefied by Kamerlingh Onnes, who shortly 

afterwards produced superfluid helium by reducing the vapour pressure 

is that work above the liquid using a vacuum pump. It is worth noting, in these days of 

mired; from plentiful supplies, that Onnes's helium was painstakingly extracted at 

will increase Leiden from large quantities of monazite sand imported from India 

emperature. especially for the purpose. 

; about 3.7 J Between the two World Wars, there was a steady development in the 

of work. In production of oxygen and nitrogen by the distillation of liquid air (the 

'ork actually process of 'air separation'), and during the 1930s plants producing around 

er cryogenic 100 m 3 (100 1) of liquid oxygen per day were in operation. Liquid helium 

a. Thus, on was still a comparatively rare and expensive commodity, the rate of pro- 

f cryogenics duction being limited to a litre or two per hour, often only on an intermittent 

basis, and the liquid being available in only very few laboratories throughout 
the world. 

Immediately after the Second World War, Professor Sam Collins, at the 
Massachussetts Institute of Technology, developed a new design of helium 
liquefier using reciprocating expansion engines, which was capable of 
making liquid on a continuous basis at a rate of several litres per hour. At 
the same time, the extraction of helium from natural gas wells, begun 
during the 1920s, had greatly increased, so that helium gas, although still 
comparatively expensive, was no longer a rare commodity. 

As a result, when, during the 1960s, Type II superconducting wire was 
produced in quantity on a commercial basis, enabling high-field super- 
conducting magnets to be constructed for the first time, liquid helium 
was readily available for cooling. This development was quickly exploited by 
those research establishments concerned with high-energy nuclear physics, 
since the saving in energy costs compared with those of an equivalent 
water-cooled system quickly outweighed the much higher capital cost. 
As confidence was gained, magnets of increasingly complex design were 
constructed, so that each of the major laboratories now contain several 
tens of superconducting magnets. In parallel with these developments, 
refrigerators incorporating expansion turbines rather than reciprocating 
engines were developed; a number of refrigerators capable of extracting 
several kilowatts at 4 K have now been built. 

As to the future, it is clear that the production of oxygen, nitrogen and 
argon by the fractional distillation of liquid air will remain a major industrial 
process for many years. The transport of liquefied natural gas by sea at 
present forms a vital link in the world's fuel supply system, but will decrease 
in importance as supplies of natural gas diminish and other energy sources 
are developed. Hydrogen may well be one of these fuels, but at present in 



energy terms it is expensive to produce, requiring large amounts of primary 
energy, and the liquefaction process also consumes much energy. Liquid 
hydrogen, therefore, may never be economically viable as a fuel other than 
for a few specialised applications. 

Superconducting magnet technology has assumed great importance, and 
since it is economically attractive compared with the use of conventional 
magnets and can also produce more uniform and time-invariant fields, 
applications are expanding. For a number of years, superconducting mag- 
nets have been routinely manufactured for experimental work in physics 
and chemistry, notably for nuclear magnetic resonance (NMR) and electron 
spin resonance (ESR). These methods have recently been extended to 
biological applications and now to medical diagnosis. This latter provides 
the first truly large-scale, commercial application of superconductivity. 

Although superconducting motors, generators, transmission lines, and 
so on have been under active development in a number of countries, the 
scenario so far has been that each advance in superconducting electrical 
engineering has been matched by an advance in the corresponding room- 
temperature technology. Since the latter is usually less complex, it has been 
more attractive on the grounds of both cost and reliability. 

In electronic engineering, the Josephson effect opened new prospects in 
the precise determination of voltage, in the measurement of very small 
magnetic fields and in rf applications. Devices based on the Josephson 
effect are now used on a routine basis. 

Thus, although cryogenics is a field of relative antiquity, there has been 
an unusually long time between the discovery of some phenomena and 
their commercial exploitation. This was particularly so in the case of 
superconductivity, which was discovered in 1911 but only ceased to be a 
laboratory curiosity some 50 years later. On the other hand, devices using 
the Josephson effect were marketed within a few years of its prediction and 
discovery. 



1.4 Liquefied Natural Gas (LNG) 

Natural gas is typically composed of 85-95% methane, the remainder 
being mainly nitrogen, ethane, propane and butane, although quantities of 
heavier hydrocarbons, carbon dioxide, water, sulphur compounds and, 
occasionally, mercury, may also be present, the precise composition 
depending upon the reservoir from which it is extracted. Certain sources, 
notably in Kansas, are comparatively rich (about 0.4%) in helium and are 
the major sources of this element. Natural gas is extracted by drilling in a 
way similar to that used for oil production and is somewhat refined before 



B. A. HANDS 



1. A SURVEY OF CRYOGENIC ENGINEERING 



7 



imounts of primary 
uch energy. Liquid 
as a fuel other than 

at importance, and 
lse of conventional 
ne-invariant fields, 
>erconducting mag- 
tal work in physics 
NMR) and electron 
been extended to 
rhis latter provides 
iperconductivity. 
smission lines, and 
er of countries, the 
inducting electrical 
^responding room- 
omplex, it has been 
•ility. 

;d new prospects in 
ment of very small 
i on the Josephson 

rity, there has been 
tie phenomena and 
so in the case of 
Dnly ceased to be a 
hand, devices using 
Df its prediction and 



ine, the remainder 
though quantities of 
ir compounds and, 
irecise composition 
;d. Certain sources, 
>) in helium and are 
cted by drilling in a 
what refined before 



use: the heavier hydrocarbons are separated as natural gas liquid (NGL) 
or as liquefied petroleum gas (LPG), and the nitrogen content may be 
reduced. 

Natural gas was used on a local basis in the United States during the 19th 
century for both fuel and heating; by the 1940s it was being distributed by 
pipeline throughout much of the country and now provides about a quarter 
of America's energy requirements. Since about 1975, Great Britain has 
relied entirely on natural gas for its gas supplies; it forms a significant part 
of Japan's energy consumption; and its use is widespread throughout 
Europe and the USSR (Table 1.1). 



Table 1.1 

Past and Projected Consumption of LNG (10 6 t/year)° 



Year 




United States 


Western Europe 


Total 


1975 


5.0 


0.25 


8 


13.3 


1980 


19 


11 


11 


41 


1985 


44 


39 


22-36 


105-119 


1990 


47-55 


50-105 


33-39 


130-199 






Sources of natural g 


as (10 6 t/year)' 





Americas USSR Middle East Far East Africa Total 



1980 1 - 3 15 22 41 

1990 6-30 9-35 13-17 35-39 67-78 130-199 



Sources of natural gas are scattered relatively evenly around the globe, 
with the result that a trade has developed in transferring the gas to areas 
of large demand. Thus there are, for instance, major pipelines from Alaska 
southwards, and from the USSR to Western Europe. However, much gas 
is liquefied for both transport and storage to take advantage of the large 
decrease in specific volume which is achieved without the necessity for 
pressurisation. 

The first shipments of LNG by sea were made on an experimental basis 
from Lake Charles, United States, to Canvey Island, England, during 1959, 
and as a result of the success of these voyages a regular service from Algeria 
to Canvey Island was instituted in 1961, carrying about 700,000 t/year. 
Twenty years later, routes had been established from Algeria and Libya to 
Europe, from Algeria to the United States, and from Alaska, Abu Dhabi, 



Fig .1.1 The LNG tanker 'LNG Aquarius', launched in 1977, L.O.A. 285 m The LNG 
LTco^alion^" 03 ' alUmi " iUm tank5, each of 25 - 260 m3 opacity. (Courtesy of British 



Indonesia and Brunei to Japan, and another ten or so routes were under 
active development [1.4]. The shipping terminals are supplied by large 
liquefiers with up to 5000 t/day capacity in a single train (Fig 16 22) 

Apart from storage at liquefaction plants and trading terminals, natural 
gas is stored as liquid for 'peak shaving' operations, that is, to provide an 
additional source of gas during periods of peak demand when the normal 
£5? //PTT 15 inade 1 uate < usuall y in wi n*r). Liquefaction, using small 
(200 t/day) plants takes place during periods of low demand in the summer 
Storage tanks may be as big as 100 m in diameter and 30 m in height 
containing tens of thousands of tonnes of liquid (Fig. 1.2). In the past they 
were usually constructed of either aluminium or 9% nickel steel- now 
prestressed concrete (with a suitable thin metal liner to eliminate porosity 
problems) is being increasingly used. During the 1960s, a number of tanks 
were formed by excavating a hole in the ground and installing a thin 
steel liner, but this design has proved to be unsatisfactory due to large 
evaporation rates and to an ever-increasing area of frozen ground around 
the tank, although new designs are now being developed in Japan 



\. HANDS 




B. A. HANDS 

to SbutfrN^Tr^'f ties ' in some areas il has P roved econ °™ 

L noint of u^ y , T d t0 ^ 11 in Sma " St ° rage vessels c,ose *> 
ITh j f ' 1116 technol °gy adopted is similar to the well-established 
methods used for oxygen and nitrogen. 

Jtl^T a ^° n (<Upgradin g') of natura l gas is achieved by cryogenic 
and carho T^T™"* 8 ^ain significant quantities of nitrogen 
, n ™ Z i*' u h,Ch redUCe the catorific va,ue and ^nder the gas 
ncompabble with other supplies to the pipeline distribution network. 
Upgrading plants are based on successive liquefaction and separation of 

^Z 1 Ti C °Z POn T ° f natUral gaS and are fre£ l uentl y inst a»ed at the 
weH-head. In these plants, solid impurities (sand, etc.) are filtered, and 
then water, sulphur compounds and carbon dioxide are removed using 
tn ?L m h C 7 1 S16VeS ° r Ch6miCal absor Ption, for example, using glycol 
to absorb water or monoethanol amine to absorb carbon dioxide. Liquefac- 

exl?! PlaCC ***** b, ° Cking the ^"temperature heat 

exchangers with frozen components of the gas. Currently, natural gas 
t ar 4 pr °J eCting a si ^^ Urease in the number and size of 
such plants. This increase is associated with the use of nitrogen injection 
mto the gas weUs to enhance gas recovery, thus creating a double use of 
cryogenics for both injection and rejection, since the nitrogen will be 
produced on-site by the fractional distillation of liquid air. 



1.5 Air Separation 

The production of oxygen, nitrogen and argon by the fractional distillation 
of air, or air separation' as it is known, forms a vital part of the infra- 
structure of the industrialised world. The major developments have 
occurred since the Second World War: in 1948, a system to produce 140 
t/day of liquid oxygen was built in the United States; in the 1970s plants 
with ten times that capacity were under construction in various part's of the 
world. The daily world production of oxygen is now about 5 x 10 s t (Fie 
1.3), a purity of around 99.5% being easily achievable even on this scale 
By far the greatest amount of oxygen is consumed by the chemical and 
stee industries (Table 1.2). Since the daily consumption of a chemical or 
steel works may amount to several hundred tonnes per day, it has become 
common practice to build an air separation plant on an adjacent site and 
deliver the oxygen by pipeline. Because a continuous supply is essential 
stringent conditions may be imposed by the user, and emergency electrical 
generators and back-up storage vessels may have to be provided to guaran- 
tee a supply until faults can be rectified or oxygen brought in by road 



4ANDS 

>nomic 
lose to 
)lished 

ogenic 
trogen 
he gas 
twork. 
tion of 

at the 
d, and 
I using 

glycol 
juefac- 
e heat 
ral gas 
size of 
jection 

use of 
will be 



illation 
; infra- 
s have 
ice 140 

plants 
3 of the 

t (Fig. 
5 scale, 
cal and 
lical or 
jecome 
ite and 
sential, 
ectrical 
juaran- 
oad. 




A considerable quantity of oxygen is produced in gaseous form and 
compressed into cylinders to be used, for instance, for welding, in diving and 
hospitals. Other important and growing uses for oxygen are in the partial 
oxidation of coal and heavy hydrocarbons to synthesise gas mixtures for 
methanol production and to produce hydrogen for ammonia production, 
and in the treatment of waste water by activated sludge processes. The use 



Table 1.2 

Industrial Consumption of Oxygen in the United States in 1979- 
Percent of total consumption 

Steel making 

Basic oxygen process 39.6 

Open hearth process 9.3 

Electric furnace 1.7 

Cutting, welding, blast 

furnace air enrichment 14.8 

Total 65.4 
Non-ferrous metals 3.0 
Fabricated metal products 7.0 
Chemicals 

Ethylene oxide 8.2 

Acetylene 3.8 

Titanium dioxide 2.8 

Propylene oxide 2.3 

Vinyl acetate 2.3 

Other 0.6 

Total 20.0 
Pollution control 3.0 
Miscellaneous 1.6 



"From Thorogood [1.3]. 



12 



B. A. HANDS 



1. A SURVEY C 



of oxygen in the production of fuels from coal is expected to increase as 
oil reserves diminish, an important aspect of this being the very large 
consumption which will be required at an individual site, perhaps 20,000-. 
30,000 t/day: the SASOL II complex which is operational in South Africa 
uses 15,000 1 of oxygen per day. 

Liquid oxygen is also produced in quantity for use in aerospace activities, 
both as a fuel oxidiser and for life support systems. The amounts required 
can be large: for instance, each Apollo flight to the moon consumed about 
2000 1 (Fig. 1.4), and the annual consumption of the American space 
programme at its peak was about 400,000 1 [1.5]: 

At the same time as oxygen is separated from air, nitrogen is also, of 




course, produi 
oxygen. In th 
by-product an 
developed an 
production. 

Liquid nitro 
cations, such { 

(1) for coc 
tamination mu 

(2) forfref 
uses up to 700 

(3) in the i 
either side of i 
whole system; 

(4) in reck 
of many meta 
cold motor ve 
constituents se 
can be shattere 
which does no 
treated. In Bel 
being fragment 
consumption c 
from the non-f 

(5) in defla 
deflashing can 
each item indri 

(6) in the l 
resistance of a 

(7) for the 
the cattle indu: 

(8) in astro: 

(9) in groui 
to be performe 

(10) in bon 
porarily harmle 

However, th 
for various che 
dependent upoi 
for such applic; 
and chemical 1 



1. A SURVEY OF CRYOGENIC ENGINEERING 13 
course produced, the current world-wide consumption being about that of 
oxygen In the early years of the industry, nitrogen was considered a 
by-product and sold relatively cheaply. However, new uses have been 
developed and some plants are now biassed more towards nitrogen 

Pr nquidnitrogen is a useful source of cold and finds a diversity of appli- 
cations, such as: 

(1) for cooling cold traps in vacuum systems, especially where con- 
tamination must be avoided, as in semi-conductor device manufacture; 

(2) for freezing food: one major fast-food franchise m the United Mates 
uses up to 700 t/day for freezing hamburgers; 

(3) in the repair of pipelines: by freezing the liquid in the pipeline on 
either side of the fracture, a repair can be effected without emptying the 
whole system; , , , .... m . 

(4) in reclamation processes, where use is made of the embnttlement 
of many metals and polymers, at low temperatures, when, for instance, 
cold motor vehicle tyres can be pulverised, and the steel and polymer 
constituents separated and re-used; the polymer coating of electric cables, 
can be shattered into small pieces while the copper or aluminium conductor, 
which does not become brittle, remains intact. Large items can also be 
treated. In Belgium, for example, complete automobiles are cooled before 
being fragmented; it is claimed that the process reduces the overall energy 
consumption of the process and makes it easier to separate the ferrous 
from the non-ferrous (non-embrittled) scrap; 

(5) in deflashing of moulded polymer products: in the embrittled state, 
deflashing can be achieved by a tumbling process rather than by treating 
each item individually; 

(6) in the heat treatment of metals: for instance, to improve the wear 
resistance of certain tool steels; 

(7) for the storage of biological specimens, especially bull semen for 
the cattle industry; 

(8) in astronautics, for pre-cooling fuel tanks prior to filling with oxygen, 

(9) in ground freezing, to enable tunnelling and excavation operations 
to be performed in wet and unstable soils; 

(10) in bomb disposal, for freezing explosives to render them tem- 
porarily harmless. 

However the widest use for nitrogen is as an inert blanketing gas 
for various 'chemical and metallurgical processes. The purity required is 
dependent upon use, with medium purities (1-3% oxygen) being acceptable 
for such applications as blast furnace feed systems, coal handling systems 
and chemical tank purging. High purity (less than lOppm oxygen) is 



14 B. A. HANDS 

essential for many purposes, of which steel annealing, float glass manu- 
facture and fabrication of semi-conducting devices are important examples. 
Gaseous nitrogen is also used as a feedstock for the production of some 
chemicals, particularly ammonia. For large-scale uses, the nitrogen is sup- 
plied by an on-site plant or by pipeline. In other cases, it is often convenient 
to store the nitrogen as liquid rather than as gas in cylinders and vaporise 
it as required. 

As already mentioned, a relatively recent and growing use of nitrogen is 
as a displacing medium in the recovery of oil and gas. By forcing oil or 
natural gas out of the well under pressure, a significant increase in the 
percentage extracted can be achieved. Such applications are of large volume 
and require delivery pressures between 130 and 700 bars. 

The other major constituent of air is argon, which is in great demand for 
inert blanketing when nitrogen is too reactive, and for inert gas-shielded 
welding (TIG, MIG, etc.), although helium tends to be preferred in the 
United States. Because a very high purity (>99.9%) is required for most 
purposes, the impure product from several air-separation plants may be 
sent to a central point for purification. The air-separation industry is, in 
fact, so competitive that the recovery of argon may be necessary to prevent 
a plant running at a loss. The demand for argon is increasing rapidly, and 
it is possible that in the future some air-separation plants will be operated 
for the production of argon only, the nitrogen and oxygen being discarded. 
Although much.argon is supplied as compressed gas, it is more economical 
for even moderate users to receive and store argon as liquid. 

Of the minor constituents of air (Table 1.3), neon, krypton and xenon are 
extracted mainly for use in the lamp industry and laboratory instruments. It 
is not at present economic to recover helium due to its availability from 
LNG wells. 



Table 1.3 

Potential Yield of Atmospheric Rare Gases from a 1000 t/day Oxygen Plant" 



Total in air passing 

through plant Typical yield 

(m 3 /hr at NTP) (%) Cylinders per day 



Argon 


1395 


55 


2800 




2.7 


60 


6 


Helium 


.0.75 


60 


. 2 


Krypton 


0.17 


30 


0.2 




0.014 


30 


0.015 



" From Thorogood [1.3]. 



1. A SURV 

1.6 Liquid 

Hydrogen 
explosive < 
(0.02 mJ a 
no unusua 
1970s, whe 
Its import; 
for examp] 
Hydroge 
hydrocarbc 
gas or fuel 
scale, eleci 
due mainlj 
hydrocarbc 
burning h> 
Electrolytic 
hydrogen. ' 
since it cle; 
the resultin 
tigation of 
thermocher 
Hydrogei 
(Chapters 1 
higher. A cc 
and para (C 
conversion : 
being usual 
Care must i 
oxygen whi« 
believed, ca 
perature pai 
Liquid hy 
nuclear phys 
a target for 
from the enj 
to measure 
interactions . 
volume of 1« 
of a charged 
a piston in oi 



B. A. HANDS 

>at glass manu- 
rtant examples, 
uction of some 
nitrogen is sup- 
iten convenient 
rs and vaporise 

e of nitrogen is 
' forcing oil or 
ncrease in the 
>f large volume 

iat demand for 
rt gas-shielded 
referred in the 
uired for most 
plants may be 
industry is, in 
;ary to prevent 
g rapidly, and 
11 be operated 
ing discarded, 
re economical 
d. 

and xenon are 
nstruments. It 
liability from 



. A SURVEY OF CRYOGENIC ENGINEERING 



1.6 Liquid Hydrogen 



Hydrogen gas is a somewhat hazardous substance to handle due to its wide 

m^Z^T™™ rang< \ With 3ir (+ - 72% > and its ,ow **** energy 
(0.02 mJ a 30% concentration), although the liquid itself appears to present 

? 9 Tr h en r 5rr and K WaS " WidC US£ f ° r P»^ ses ™* ^ 

1970s, when liquid helium became more easily available in large quantities 
Its importance as a cryogen has declined considerably since then, so that' 
for example, ,n Great Britain it is no longer commercially available. ' 

Hydrogen gas is produced on a large scale by the reaction of steam with 
hydrocarbons particularly natural gas, or by the partial oxidation of natural 
gas or fuel oil. The gasification of coal may also be used. On a smaller 
scale, electrolysis of water is used, in spite of its higher cost, which is 
due mainly to the higher binding energy of hydrogen in water than in 
hydrocarbons, to the high cost of electricity (itself often produced by 

FlTnL y K F T } ' t0 thC l0W efficiencv of electrolytic cells 
Electrolytichydrogen may cost twice as much as the cheapest 'chemical' 

^°> en .' 15 CUrrCntly intCreSt in devel °P in g hydrogen as a fuel, but 

since it clearly does not make sense to produce it from other fuels (with 
the resulting overall loss in available energy), there is widespread inves- 
tigation of me hods for producing hydrogen from water using various 
thermochemical methods. 
Hydrogen may be liquefied using cycles similar to those in use for helium 

2,? T ^ } ' CXCept th3t thC Cyde P ressures are about ^e times 
ST,' A ^ phcat '° n * that, because hydrogen exists in two forms, ortho 
and para (Chapter 2), the inclusion of catalysts to promote ortho-to-para 
conversion must be considered. Great care must be taken with safety it 
being usual to provide a blast wall between the liquefier and its operators 
Care must also be taken to free the hydrogen from impurities, especially 
oxygen which can promote unwanted ortho-para conversion, and it is 
believed, cause an explosion if accumulated as solid in the lower' tem- 
perature parts of the plant. 

Liquid hydrogen still finds two particular applications. In high-energy 
nuclear physics experiments, liquid hydrogen or deuterium may be used as 
a target for the particles produced from the accelerator. More interesting 
from the engineering point of view is the bubble chamber, which is used 
o measure the properties of charged particles and to elucidate their 
interactions anc I decays. A bubble chamber consists essentially of a closed 
volume of hquid held at a pressure well above saturation. On the passage 
of a charged particle, the pressure is rapidly reduced, usually by means of 
a piston in one wall of the chamber, so that the liquid is in the superheated 



B. A. HANDS 

is taken, and the hquid ,s recompressed before bulk boiling occurs the 
whole cycle taking a few tens of milliseconds. A large magnet surrounds 
he chamber so that the momentum of the particle can be deduced from 
heliuTh T h the K ra , Ck J Bubb,C Chambers contai ™g hydrocarbons and 
favnT^ r bee \ bmIt ' but W™*™ and deuterium are particularly 

foZd inZ^ I ^ S r P,er nUdCar StrUCtUre a,,OWS a mo - *ra lg ht- 
rhTh 1I " er P r « atlon of any interactions which occur. Hydrogen bubble 

cuT mi y a b ?V S ,3rge 35 3 m in le ^ h and -"tainfng several 

™1 TVH qUld ' bUt th6y h3Ve now been superceded by othe 

sur ounde°J hvT?' ^ ^ is t0 us * sma "- chamber 

surrounded by electronic detectors (Fig. 1.5) 

The other application for which liquid' hydrogen is still produced in 

quantity ,s as a fuel for space vehicles. When used with oxygen TiL a 

chosen for the fuel of the second and third stages of the rocket for the 

W^rSSSr ff tS !° th f moon ' «"* of which consumed abou 
J™ ( 1300 m3 ) of hqmd hydrogen (Fig. 1.4): in the late 1960s, the 
Amencan space programme was using about 40,000 t/year [1.5]. In the 
" ^ SP 1 CC Shutt,e consumes about 1 120 tonne! 
three tinL^T^u™ > ^ hydr ° gen haS 3 Calorific value a °OUt 
Zolic TZSFl T OSCne (WhiCh W3S USCd f ° r firSt ^ °f 

ZSsCn^^T pe ? nit vo,ume is about three times ,ower - ^ 

ke^lT^T hhydr0gen 1 havet0bemu chlargerthan those fuelled with 
kerosene, and this can entail problems of structural stability, particularly 
bending oscillations during flight y 

as ?S, h fn bCen W l deSP f 3d discussion of^epossibilityofusinghydrogen 

a Ltdv Inr'o / nd aUt0 , m0bUeS 35 ° U SU PP ,ies diminish ^ough 
as already mentioned a novel and energy-efficient means of producing 

of" safetT 71 h deVe,0P H ed K bef0re tWS beC ° meS 3 rea,ity - ° n the q^don 
of safety, ,t can be argued that although hydrogen is more easily ignited 

SS 1 f " e,S ' * flamC radiates litt,e Also, since hydrogen 
hS TnohM rtr^ 5 r3ther th3n ° UtWards ' so that ovefall 
ZZZ P k % t0 Ch °° Se b6tWeen the two fuels - The storage of 
hydrogen » however, a major problem. Storage as metal hydrides imposes 

absoSt^'f 1 T PCnalty beC3USe ° f the metaIs used a "d S low 
tZVeltZT"- ° rage 35 UqUid " ClCarly COnVenient ' but quires 

about 15%?cL h men H k 6 ' earher ' alth ° Ugh SOme Savi "8 in volu ™ 
(about 15%) can be made by using a mixture of solid and liquid-'slush 
hydrogen'. Considerable care would have to be taken in the'd ^sal of 
rea^f Y^"^ Perha P s a m ™ senous drawback is the^nergy 
required for liquefaction, which may amount to as much as a third of the 



B. A. HANDS 

calorific value of the fuel liquefied. This, together with the present high 
cost of production from non-hydrocarbon sources, makes hydrogen econ- 
omically unattractive, although several experimental automobiles have 
been successfully run with liquid hydrogen as fuel for a number of years 



1.7 Liquid Helium 

The importance of helium to the physicist and cryogenic engineer is that it 
is the only route to temperatures below about 10 K, apart from magnetic 
cooling methods which are unlikely to become practical on anything but a 
very small scale. The provision of helium refrigeration is, therefore, a 
necessary adjunct to the use of superconducting magnets. 

The largest sources of helium in the western world are currently the 
natural gas wells of the states of Texas and Kansas in the United States. 
Wells in Poland, Northern Germany and the USSR (at Orenburg) also 
produce large quantities. Helium is present in these wells at a concentration 
of about 0.2-0.7% and is extracted by liquefying the other constituents. 
Although at present there is plenty of helium available, there are worries 
that if the growth in both size and number of superconducting magnets 
continues at the present pace, there could be a severe shortage in a few 
decades as natural gas wells become exhausted, even though the United 
States has considerable quantities of helium stored in underground porous 
rock— a result of the so-called 'conservation' programme which has now 
been discontinued [1.6]. Outside America, 'conservation' has a rather 
different connotation— that of recycling the gas after use, rather than 
exhausting it to the atmosphere. Such recovery is usually justifiable on 
economic grounds alone, since gaseous helium is not cheap, but it is worth 
noting that large quantities are used in welding and in oxygen-helium 
atmospheres for diving, from which helium recovery is not feasible. 

A major landmark in the development of helium technology came in 
1946 with the design by Professor Sam Collins of a liquefier which did not 
require the feed helium to be pre-cooled and which could be operated 
continuously for long periods. Previous to this, small-scale experiments 
were done by liquefying helium in situ, for example, by precooling with 
liquid hydrogen (sometimes itself produced in situ) and then adiabatically 
expanding. Continuous liquefaction was achieved using cascade cooling 
with liquid air (or nitrogen) and hydrogen followed by Joule-Thomson 
expansion. The latter method could produce a few litres of helium per 
hour, but required the simultaneous operation of both a hydrogen and a 
helium liquefier, the liquid air or nitrogen usually being available from a 
commercial source; 



1. A SURVEY OF 

- The Collins i 
proved to be a 
meant that fairl 
still marketed to 
bearings were d 
liquefiers, and si 
refrigerators. Tl 
engine, have no 
high efficiency. ' 
liquefiers. 

Another probl 
to compress the 
since all will fref 
is especially imp 
to be run contii 
contaminations I 
believed that w: 
blockages in one 
received general 
based, piston rin; 
compressors, bei 
reciprocating con 
require a sophisti 
for a malfunction 
refrigerator itseli 
more frequent m 
for more massivt 
tamination is sim 



1.8 Superconduct: 

Perhaps the one i 
has been the exf 
conductivity or tl 
phenomenon was 
major part in elecl 
was destroyed by 
presence of a mag 
remained unfulfill 
'high-field' supera 
remain supercond 



B. A. HANDS 



1. A SURVEY OF CRYOGENIC ENGINEERING 



19 



present high 
irogen econ- 
lobiles have 
ber of years. 



leer is that it 
am magnetic 
lything but a 
therefore, a 

nirrently the 
nited States. 
;nburg) also 
Dncentration 
constituents. 
; are worries 
ing magnets 
age in a few 
i the United 
ound porous 
ich has now 
las a rather 
rather than 
ustifiable on 
at it is worth 
»rgen-helium 
asible. 
Dgy came in 
hich did not 
be operated 
experiments 
cooling with 
idiabatically 
:ade cooling 
le-Thomson 
helium per 
rogen and a 
lable from a 



The Collins liquefier, which used a reciprocating expansion engine, 
proved to be a reliable machine, although the presence of rubbing seals 
meant that fairly frequent maintenance was required; its derivatives are 
still marketed today. During the 1950s, high-speed turbines running on gas 
bearings were developed as the external work components for hydrogen 
liquefiers, and soon afterwards this technique was incorporated in helium 
refrigerators. These turbines, although less robust than a reciprocating 
engine, have no rubbing surfaces and can achieve a large throughput at 
high efficiency. They are now usually specified for large refrigerators and 
liquefiers. 

Another problem in the design of refrigerators arises from the necessity 
to compress the gas. The helium feed must be free of oil, water and air, 
since all will freeze at some point in the system and cause blockages: this 
is especially important today, when superconducting systems may have 
to be run continuously for many months. To achieve such service, oil 
contaminations less than 1 part in 10 7 may have to be specified, and it is 
believed that water contamination of about 3 parts in 10 8 has caused 
blockages in one system [1.7]. Two types of compressor appear to have 
received general acceptance, reciprocating compressors with dry, polymer- 
based, piston rings, and oil-flooded screw compressors. Oil-flooded screw 
compressors, being rotating machines, suffer from fewer problems than 
reciprocating compressors and are more compact and vibration-free, but 
require a sophisticated oil-removal system. Furthermore, it is not unknown 
for a malfunction to occur such that much of the oil is delivered into the 
refrigerator itself. Reciprocating compressors have the disadvantage of 
more frequent maintenance intervals, more vibration and a requirement 
for more massive foundations, but the equipment for removal of con- 
tamination is simpler. 



1.8 Superconducting Magnets and Machinery 

Perhaps the one major disappointment in the development of cryogenics 
has been the exploitation of the "electrical engineers' dream" — super- 
conductivity or the complete absence of electrical resistivity. After this 
phenomenon was discovered in 1911, hopes persisted that it would play a 
major part in electrical engineering, even though the superconducting state 
was destroyed by the passage of a current of only a few amperes or the 
presence of a magnetic field of only a few tenths of a tesla, but the dream 
remained unfulfilled for some 50 years. In the late 1950s, a range of 
'high-field' superconductors were discovered, so called because they would 
remain superconducting in fields of tens of tesla. Also, their critical tern- 



, . B. A. HANDS 

conducting magnet involved rZTl he construct '°n of a super- 

and that ^h^^^^t^? 6 ^ * Coil > 
it to operate at the fields whicJTsW 1° S 'f ''f' the magnet and allo » 
In order to optimise the perfonnance P u\ ^ ^ COU,d Un- 
learnt, and even today new ' many , Subt,e techniques had to be 
Nevertheless, magnets are now 1" h " 0t 3,WayS COI "Pletely successful 
basis, and, torla^^^^JTT^ °° * P roduc «°n-,ine 
copper equivalenfs, to whkh h ev " ^ter-cooled 
stability of field. ^ 3re SU P enor on ™ning costs and in 

Sup.rconductingmagnetshavefoundw.despreadapplicationsinre^^ 



Fig. 1.6 Small superconducting magnet for research tu- ■ 
partly from niobium-tin wire and partly from SZJ T,' * " ^'""P^ magnet > wound 
bore. The maximum diameter is about 25 cm S^n 1Um ' Pr ° dudn 8 10Tin a 70mm 
used to absorb energy should the m^cfun^iv 'Z^T ^ ° f are 
the norma, state (Quench'). (Courte y o^Z^tZ^ ** ^™ d ^ » 



i. a.surv; 

laboratory 
cubic centi 
of NMR a 
use into ch 
which the 
coming inti 
nucleus (pi 
radiation, t 
magnetic fi 
between 0.: 
the x, y ai 
correlating I 
mation may 
intensity of 
Since the w; 
body, a 3-di 
abnormalitie 
lattice and < 
acquired. Th 
(Fig. 1.7), w 
and a stabilii 
Still at a 
Spectroscopy 
nuclei due to 
resonant freq 
vivo. Process 
tissue during < 
^Na nucleus, 
Because the n 
of protons, m. 

No adverse 
MRI or MRS. 
field, which ca 
necessary), an 
ferrous objects 
For MRS an 
used, the lattei 
cryogenics for 
environments, 
conductivity, tf 
per year worldi 
Large magne 



1 (niobium) were 5-10 K 
construction of a super- 
ding the wire into a coil, 
ise' the magnet and allow 
)f the wire could sustain. 
>tle techniques had to be 
ys completely successful, 
ally on a production-line 
s than their water-cooled 
on running costs and in 

d applications in research 



is a split-pair magnet, wound 
., producing 10 T in a 70 mm 
on top of the assembly are 
from the superconducting to 
Ltd.) 



1. A SURVEY OF CRYOGENIC ENGINEERING 2 , 

laboratories. Small magnets, providing a uniform field over a few tens of 
cubic centimetres are mainly used by physicists (Fig. 1.6); the development 
of NMR and ESR techniques for analytical purposes has extended their 
use into chemistry and biology [1.8], and more recently, into medicine, in 
which the technique known as MRI (Magnetic Resonance Imaging) is 
coming into routine clinical use. In MRI, the resonance of the hydrogen 
nucleus (proton) is stimulated by applying radiofrequency electromagnetic 
radiation, the resonant frequency being directly proportional to the applied 
magnetic field. The patient is subjected to a uniform magnetic field of 
between 0.5 and 1.5 T, upon which are superimposed small gradients in 
the x, y and z directions. By changing the applied rf frequency and 
correlating the resonant frequency with the local field, 3-dimensional infor- 
mation may be obtained. The primary information is obtained from the 
intensity of the resonance, which depends upon the local proton density 
Since the water and lipid content is different in the various tissues of the 
body, a 3-dimensional image of the body structure may be produced and 
abnormalities such as tumours may be located. Measurement of the spin- 
lattice and spin-spin relaxation times enable further information to be 
acquired. The magnets for whole-body MRI require a bore of about 1 0 m 
(Fig. 1.7), with a field homogeneity as good as 0.1 ppm of the main field 
and a stability of 0.1 ppm per hour [1.8]. 

Still at a more experimental stage is MRS (Magnetic Resonance 
Spectroscopy). Slight variations in the local magnetic environment of the 
nuclei due to different chemical surroundings produce small shifts in the 
resonant frequency, and this enables chemical reactions to be followed in 
vivo. Processes which have been investigated include changes in muscle 
tissue during exercise using the 31 P nucleus, cellular biochemistry using the 
Na nucleus, and the kinetics of enzyme reactions using the 13 C nucleus 
Because the magnetic moments of these nuclei are much weaker than those 
of protons, magnetic fields of about 6 T are generally required 

No adverse physiological effects are believed to occur with the use of 
f S ° r L M * S - The main safety problems are control of the stray magnetic 
held, which can be limited by the use of iron shielding (some 20 1 may be 
necessary), and the prevention of personnel from inadvertently carrying 
ferrous objects into the region of the stray field. 

For MRS and MRI, both conventional and superconducting magnets are 
used, the latter giving superior resolution but requiring some expertise in 
cryogenics for its operation which may not be available in some hospital 
environments. This is the first large-scale, non-research use of super- 
conductivity, the current production rate being several hundred magnets 
per year worldwide. 
Large magnets have been used since the mid-1960s by high-energy 



22 



B. A. HANDS 



1. A SURVF 




Fig. 1.7 A superconducting magnet, designed for whole-body scanning, during assembly 
A field in the range 0.5-1 .5 T is produced in a bore of 1 m. (Courtesy of Oxford Magnet 
Technology Ltd.) 6 

nuclear physics establishments, at first for the focusing of ionised particle 
beams between the accelerator and the experiment, and lately in the 
accelerator itself. Such magnets are often one or two metres long with a 
bore of around 10 cm; besides simple solenoids, quadrupole and other 
configurations have been constructed. A great variety of superconducting 
magnets for other uses has now been made, for example, simple solenoids 
of several metres bore for use with bubble chambers; toroidal magnets for 
plasma physics experiments; and a 'yin-yang' configuration, weighing 341 1, 
for a nuclear fusion experiment (Fig. 1.8). Fields in the region of 10 T are 
commonplace, and some magnets are pulsed on a routine basis. High- 
energy nuclear physics and nuclear fusion, have both given great stimulus 
to the development of magnet technology. 

Applications in the generation and transmission of electric power have 
not been as successful, the enthusiasm of the manufacturers being counter- 



uring assembly. 
Oxford Magnet 



ised particle 
ately in the 
long with a 
e and other 
•.rconducting 
>le solenoids 
magnets for 
ighing341 1, 
lof 10 Tare 
basis. High- 
eat stimulus 

power have 
ing counter- 



1. A SURVEY OF CRYOGENIC ENGINEERING 23 

balanced by the caution (realism?) of the utility companies [1.9]. In general, 
the story has been that advances in 'conventional' technology have remained 
ahead of the possibilities of using superconductors. Superconducting trans- 
mission lines are a good example. In 1973, it seemed that a superconducting 
system would be economically viable for powers greater than about 1 GVA 
[1.10]. Ten years later, due to advances in insulation technology of room 
temperature systems, the figure had risen to 5 or 10 GVA, and experimental 
studies had been largely abandoned, even though in 1984 the prototype ac 
transmission line at the Brookhaven National Laboratory [1.11] was run 
continuously for 4 weeks at 1 GW, and its stability demonstrated at 100% 
overload. 

Similarly, in the 1970s there was considerable activity in the design and 
construction of models and prototypes of superconducting alternators for 
power generation aimed at eventual machines in the capacity range of 
1000-3000 MW. Superconducting alternators have two major advantages 
over conventional designs: a greater efficiency, and a size and weight 
smaller by a factor of about two. However, the increase in efficiency is 1% 
at the most, and this is easily negated if the alternators prove to be less 
reliable than the machines currently in use. The generating authorities are, 
therefore, proceeding with extreme caution, and again by 1985, activity in 
the western world in this field had considerably diminished, with only small 
programmes remaining in the USA, Japan and Germany. However, it was 
reported in 1985 [1.12] that in the USSR, an experimental alternator was 
switched into the Leningrad supply in the summer of 1984, and that 
construction of 300 MVA alternators is proceeding. 

At present, only one superconducting device is believed to be in use by 
an electricity supply authority in the western world. A superconducting 
magnet capable of storing 38 MJ of energy has been installed at the Tacoma 
substation of the Bonneville Power Administration in the United States. 
Energy is transferred between the magnet and the transmission line in a 
controlled way to damp out subsynchronous oscillations in the ac electricity 
supply [1.13]. An advantage of the system is the relatively fast response 
time of 10 ms. Much larger magnets have also been proposed as 'peak 
shaving' energy storage devices, which would be used in much the same 
way as pumped water storage is now. 

There has been considerable interest in superconducting motors. The 
most promising application appears to be for ship propulsion, where, for a 
given power, a superconducting motor combined with a superconducting 
generator is much smaller than a conventional system. The motors are 
generally of the dc homopolar type. The small rotating mass facilitates 
rapid speed changes, and the motor will operate efficiently at low speed, 
thus removing the need for a gear box. However, on economic grounds a 



24 



B. A. HANDS 



conventional system is still superior, and the main use for a superconducting 
unit may be in naval vessels, for which flexibility and small size are important 
advantages, and in icebreakers, because of the frequent reversals of direc- 
tion at low speed. 

A different form of power unit is the linear motor, which, when combined 
with magnetic levitation, forms a suitable system for driving high-speed 
trains. Japanese National Railways has pursued such a development [1.14], 
intended for the commuter line between Kobe and Tokyo, which was 
predicted to reach full capacity soon after 1980. Work started in the 1960s, 
and the first prototype was successfully tested in 1975. Since then, the 
design has been considerably refined, and in 1979 the version known as 
ML-500 ran at 517 km/ hr, a world record. Propulsion is by linear synchron- 
ous motor, the high-frequency ac power being provided by coils mounted 
on the track. Guidance and support are both achieved using a repulsive 
electromagnetic inductive method, which requires the train itself to be 
equipped with powerful magnets. In the Japanese system, each vehicle 
(28.8 m long and weighing about 10 1) is provided with eight super- 
conducting magnets of 700 kA-turns each and on-board refrigeration (Fig. 
1.9). Although the project is well advanced, there are no plans yet to 
introduce the train into commercial service, since passenger density on the 
line has increased slower than originally predicted. 

Finally, one other use of superconducting magnets is showing commercial 
promise. In the 1960s, it was established that kaolin, which is used in paper- 




Fig. 1.8 'Yin-yang' magnet for the Mirror Fusion Test Facility in Berkeley, California, 
(a) Opposite: Coil-box assembly (courtesy of University of California Lawrence Berkeley 
Laboratory), (b) Magnet during installation in the vacuum vessel, which is about 20 m in 
diameter. The (rectangular) end views of six cryopump modules for maintaining a high vacuum 
can also be seen, arranged radially around the top two-thirds of the vacuum vessel. This 
photograph indicates the complexity of a modern large cryogenic installation. (Courtesy of 
University of California Lawrence Livermore National Laboratory and U.S. Department of 
Energy.) 



26 



B. A. HANDS 




making, could be whitened by removing the discolourants, which are 
principally due to traces of iron, by passing the clay through a magnetic 
field gradient. Since then, applications have been found in the separation 
of ores, in the purification of chemicals, in the desulphurisation of coal and 
in the cleaning of flue gases and liquid effluents. The separation of red 
blood cells from plasma is also possible. Although many of these processes 
require only comparatively low magnetic fields, the use of superconducting 
magnets may be advantageous for certain applications [1.15]. 



1.9 Cryogenic Electronics 

Many active electronic devices can be operated in a cryogenic environment 
[1.16]. They are generally of the field-effect transistor (FET) type and are 
based on silicon or gallium arsenide. For instrumentation purposes, there 
are clear advantages in placing at least some of the electronic circuitry close 
to the sensing head. However, there may also be inherent advantages in 
operating transistors at low temperatures, such as increased switching speed 
or lower noise. A serious problem is the effect on device reliability of the 
stresses induced by thermal cycling. 



"ower lead 
M terminal 



lich are 
lagnetic 
>aration 
oal and 
of red 
ocesses 
ducting 



nment 
nd are 
there 
/ close 
ges in 
speed 
of the 



1. A SURVEY OF CRYOGENIC ENGINEERING 

Superconducting electronic devices are in a dittos , i ^ 
two phenomena-the Josephson effect Inc thf! ^ 
flux, which are described in a «mp£ way m M » atlon °f magnetic 
more complete account is given in H 181 ™ 11 f ° f example ' whi,e a 
extremely small: 2.07 x 10"^ ' qUantUm ° f ma g netic * 

amount of the earth's field ^ncloseT^ ^ZlZ^V^ * the 
Josephson effect is observed when two „? * 8 ^ m d,ameter - The 
lead or niobium) are sepTateX 7^^^^^ 

oxide film about 20 nm ii^^^^^ ^ P erha P s » 
such a layer, but so can the oair ai ^ \ B le / e i, ectrons tunnel through 
superconductivity is attribu^ so that 6 %*? m P a ^) to which 

superconductor, althou^ mSU,atlng ,ayer behaves as a 

function of the Coop^S^^^^J? the P hase <* ^ wave 
Josephson junctionare^wuseT^ 

uncertainty in the maintained vlf eMb,ed the 

The superconducting quantum in^^^ f ^ ?-^ V - „ 
from a superconducting loop containing at least I! . } 15 fonned 
If the loop encloses some magnetic fl^ there ^ust bt P ^ JUnCti ° n - 
because it is superconducting This cu™, ™ ! ! ^circulating current 
wave functions form standing w^ves rZd th" ^ Whose 

there is a phase discontinui tv til I * e nng ' Across the junction, 
hence of the magn^dc flux T " 3 fUnCt, ° n ° f the CUrrent flo U and 

looSs^^ 

drive a current round tLToTsoxh^lZ^ a ™ g edto 
measure of the magnetic flu? hi? g aCr0SS the circuit is a 

Josephson ja^^^^VS^t^ T "° ^ < W ° 
through the parallel circuit so forced TheTolta/e reouirSr 1 I 
current is then a function of the magnetic 2 q h t0 P r ° dUCethe 
Superconducting quantum interfer^ H apped ,nS,de the loo P- 

nologies similar g ?o thosTu ef fo^e^T* be{ ^^yt e cl 
»^od»mayalK,beu^.^rf^ t 2S? d alth ° Ugh 0ther 

dc SQUID is the more sens £ve an t " ^ T *V° ' ^ and USC; the 
be approached Bv forming tne q u antum limit of sensitivity can 

be measured in the P^^^STiT 
-st^ons, SQUIDs are 



B. A. HANDS 



1. A SUR 



associated with bodily activity, the fluctuations ranging from 10 _11 T 
(from the heart) down to 10~ 15 T (from the brain) [1.19]. Gradiometer 
arrangements are often used in an attempt to reduce to an acceptably low 
level the effects of local field fluctuations due to electrical equipment and 
ionospheric phenomena. Advantages over the use of ECG and EEG are 
that electrodes do not have to be attached to the patient, and that the 
measurements are localised rather than averaged over some distance. By 
spatial scanning, a 3-dimensional image of, for example, brain activity can 
be constructed and the position of a malfunction pin-pointed. With a single 
detector, such an image may take several days to produce, but attempts 
are being made to develop multiple arrays using several tens of SQUIDs 
to reduce the scanning time. It may be observed that whereas MRI (Section 
1.8) gives information about the structure of tissue, these magnetic field 
measurements give information about the functional behaviour of the 
tissue. SQUIDs have also been used to detect accumulations of ferro- 
magnetic material in various parts of the body. 

Josephson junctions may be arranged in a variety of ways for other 
purposes. For instance, a sampling oscilloscope has been made with a time 
resolution of 2 psec. But perhaps the best-known application is to comput- 
ers. Combinations of Josephson junctions can be designed to act as a very 
fast switch with low power dissipation or as a memory element. The 
theoretical switching time is about 10 psec and the power dissipation about 
1 /iW, giving a product of switching time and power consumption — the 
figure of merit used for switching devices — several orders of magnitude 
better than that of transistors. The fabrication of logic elements using such 
devices allows in principle the construction of a large capacity, compact, 
high-speed computer [1.20]. Much development work was carried out on 
this concept during the 1970s, especially by IBM. However, after '15 years 
and an estimated 100 million dollars' [1.21], IBM announced in 1983 that 
the project was abandoned, although development work in fact continues 
at a lower level. During that time, complete logic boards had been devel- 
oped and tested. Major problems with the technology are that large fan- 
out ratios are difficult to achieve and that superconducting circuits have a 
very low inherent impedance and so are difficult to couple with conventional 
elements at room temperature. There were also manufacturing problems, 
since the boards could only be tested when in the superconducting state at 
a low temperature, and some logic gates were always destroyed due to 
thermal cycling. Another factor was that, as in other branches of super- 
conductivity, room-temperature devices were being developed which 
approached the advantages offered by the superconducting system; for 
instance, at the end of 1985, it was reported that miniature ceramic circuit 
boards and hot electron devices were being developed by Fujitsu of Japan 
for use in an ambient-temperature computer which would be very much 



B. A. HANDS 



1. A SURVEY OF CRYOGENIC ENGINEERING 



29 



ations ranging from 10 -11 T 
e brain) [1.19]. Gradiometer 

0 reduce to an acceptably low 
le to electrical equipment and 
he use of ECG and EEG are 

to the patient, and that the 
raged over some distance. By 
or example, brain activity can 
:ion pin-pointed. With a single 
lays to produce, but attempts 
using several tens of SQUIDs 
'ed that whereas MRI (Section 
jf tissue, these magnetic field 

functional behaviour of the 
etect accumulations of ferro- 
■dy. 

1 a variety of ways for other 
>pe has been made with a time 
iown application is to comput- 
in be designed to act as a very 

as a memory element. The 
id the power dissipation about 
and power consumption — the 
-several orders of magnitude 
in of logic elements using such 
of a large capacity, compact, 
nent work was carried out on 
BM. However, after '15 years 
, IBM announced in 1983 that 
jpment work in fact continues 
i logic boards had been devel- 
technology are that large fan- 
lperconducting circuits have a 
ult to couple with conventional 
also manufacturing problems, 
n the superconducting state at 
vere always destroyed due to 
is in other branches of super- 
vere being developed which 
: superconducting system; for 

that miniature ceramic circuit 
developed by Fujitsu of Japan 
zr which would be very much 



faster than a Josephson machine. However, work continues towards the 
construction of a complete superconducting computer in Japan, where 
there have recently been striking advances in fabrication technology and 
architecture. 



1.10 Cryogenics in Space 

The large-scale applications of cryogenic technology to aerospace engin- 
eering have already been mentioned, in particular the use of liquid oxygen 
and hydrogen to power launch vehicles, and the use of liquid nitrogen for 
precooling purposes. In addition, liquid or cold supercritical oxygen is 
carried for life support, and helium may be carried for pressurising fuel 
tanks. The technology is similar to that used on earth, except that weight 
is at a premium, and, once in the space environment, only minimal thermal 
insulation may be needed. However, the absence of gravity poses serious 
problems, since liquid no longer separates from vapour and convection 
currents are non-existent. Special devices have to be used to overcome 
these problems. In the case of rocket motors, the vehicle may be given a 
small acceleration by an auxiliary rocket to drive the liquid towards the 
fuel tank outlet so that the engines may be started reliably. 

The small-scale applications are mainly concerned with scientific meas- 
urements, including astronomy covering the whole range of electromagnetic 
wavelengths, recording of magnetic fields and observations of the surface 
of the earth. The instruments used often include a cooled detector or a 
superconducting device. The provision of a small refrigerator (see Chapter 
17) is attractive, but the device must be of long life (several years), 
utterly reliable and low in power consumption, weight and vibration. The 
alternative is to provide a store of cryogenic liquid, but the experiment 
then has a comparatively short lifetime. Both methods are, in fact, used. 



1.11 Medical and Biological Applications 

Cryogenics has found a number of applications in the medical and biological 
fields. The use of superconducting magnets in MRS and MRI has already 
been discussed, as has the use of SQUIDs. Low temperatures are used 
more directly to enable biological materials to be frozen and stored, 
particularly thin tissues and blood. The preservation of large items is more 
difficult, since the cells suffer damage during the cooling and warming 
processes, the rapidity of which is inevitably controlled to a great extent 
by^the thermal conductivity of the material, although the injection of certain 
chemicals can minimise the damage in some cases. On the other hand, this 



30 B. A. HANDS 

damage is put to good use in the elimination of tumours by freezing. A 
major difficulty here lies in the monitoring and control of the frozen region. 
There is also insufficient understanding of the mechanisms by which cells 
are killed. Nevertheless, successful results have been obtained in the 
treatment of some conditions, and it is probable that cryosurgery will be 
more widely used in the future [1.22]. 

In agriculture, for many years cattle semen has been routinely preserved 
in liquid nitrogen for subsequent artificial insemination, and this has made 
a major contribution to the development of the industry, especially in the 
underdeveloped countries. 



1.12 Cryopumping 

Cryopumping — the removal of gas from a system by solidification onto a 
cold surface — has a number of advantages over other methods of producing 
vacua. A cryopump consists essentially of a metal plate cooled to a low 
temperature, and, therefore, can be made easily and economically in a 
large size, with considerable freedom in design configuration [1.23]. It is a 
'clean' pump, since the only working substance is the refrigerant used for 
cooling, which does not come into contact with the vacuum space. Lastly, 
all gases except helium can be pumped to extremely low partial pressures 
(Fig. 1.10). 

Although the concept of the cryopump is straightforward, the con- 
struction requires some sophisticated design, since the low-temperature 
parts must be carefully shielded from room-temperature radiation while 




Fig. 1.10 Vapour pressure-temperature curves for atmospheric gases. 



B. A. HANDS 



1. A SURVEY OF CRYOGENIC ENGINEERING 



31 




32 B. A. HANDS 

allowing free access to gas molecules. This is especially so for cryopumps 
with stages at 20 K or 4 K, which must be shielded with panels at around 
80 K. Since some molecules are scattered away from the cryopumping 
surface itself by the shields, the overall capture coefficient (which is usually 
between 0.35 and 0.5 depending on the design) is much less than that of 
the bare panel and, in fact, is not much different from that of a large 
diffusion pump. 

Very large cryopumps were developed during the 1950s for use in space 
simulation chambers. Frequently, these used panels cooled to 20 K using 
a refrigerator with helium gas as the working fluid, and radiation shields 
cooled either with liquid nitrogen or with helium gas at around 100 K. 
The residual hydrogen and helium was extracted using conventional high- 
vacuum pumps. The cryopumps usually covered almost the whole of the 
interior surface of the vacuum vessel, which typically might be several 
hundred square metres in area. 

Recently, attention has turned to the provision of cryopumps for nuclear 
fusion experiments. These are required to pump hydrogen at speeds of 
10 6 -10 7 1/sec and to pressures of the order of 10" 5 mbar or better, so that 
the coolant must be liquid helium at around 3.5 K. A number of large 
pumps of this type have now been constructed; advantage has been taken 
of the geometrical freedom mentioned earlier to produce some interesting 
configurations [1.24] such as that shown in Fig. 1.11. 




Fig. 1.12 Typical design of a small cryopump attached to a displacer refrigerator and 
intended to replace a diffusion pump. 



1. A SURVEY C 

At the othei 
cryopumps for 
be scrupulous] 
apertures of a 
direct replacen 
contained refr: 
provides refrig 
of course, purr 
temperature p 
residual hydro] 
and zeolites ha 
low pressures ; 
restricted by a 



1.13 Instrumer 

The instrumen 
mometer, pro! 
lation. The lal 
if accurate am 
procedures, as 
examined in C 

The measure 
liquids, float g 
allow the gas 
temperature of 
resistors or dio 
measuring cum 
in the liquid, a 
change in heal 
unreliable beca 
heat transfer a 
and a static liqi 
of the liquid all 

In the author 
hydrostatic hea 
to room tempei 
temperature en 
rising up the m 
that the liquid 



B. A. HANDS 



1. A SURVEY OF CRYOGENIC ENGINEERING 



33 



r cryopumps 
ils at around 
:ryopumping 
ich is usually 
than that of 
it of a large 

use in space 
d 20 K using 
ition shields 
Dund 100 K. 
itional high- 
vhole of the 
t be several 

> for nuclear 
it speeds of 
tter, so that 
jer of large 
been taken 
: interesting 



At the other end of the size scale, there is an increasing interest in small 
cryopumps for industrial purposes, especially where oil contamination must 
be scrupulously avoided as in the semi-conductor industry. These have 
apertures of a few tens of centimetres and are frequently designed to be a 
direct replacement for a diffusion pump. They are cooled with a small self- 
contained refrigerator based on a displacer cycle (see Chapter 17) which 
provides refrigeration at around 100 K for the radiation shield (which also, 
of course, pumps water vapour), and cooling at around 20 K for the lower 
temperature panel, which is equipped with a sorbent material to pump 
residual hydrogen (Fig. 1.12). Sorbent materials such as activated charcoal 
and zeolites have attracted attention on account of their ability to achieve 
low pressures at comparatively high temperatures. However, their use is 
restricted by a low pumping speed and a limited absorption capacity. 



1.13 Instrumentation 

The instrument most commonly used in cryogenic engineering is the ther- 
mometer, probably on account of its cheapness and simplicity of instal- 
lation. The latter is deceptive, however, and great care must be taken 
if accurate and reliable measurements are to be obtained. Installation 
procedures, as well as the many different types of sensor available, are 
examined in Chapter 18. 

The measurement of liquid level can present problems. For the denser 
liquids, float gauges can be used, provided that the float is designed to 
allow the gas inside to contract or even condense, depending on the 
temperature of-the liquid. A popular electronic device is a chain of carbon 
resistors or diodes which essentially act as resistance thermometers. The 
measuring current is adjusted so that when the sensor ceases to be immersed 
in the liquid, a large temperature change of the sensor occurs due to the 
change in heat transfer coefficient. However, the method tends to be 
unreliable because the current must be carefully adjusted and because the 
heat transfer coefficient can be similar in a fast-flowing stream of vapour 
and a static liquid. Difficulties can also arise if the saturation temperature 
of the liquid alters due to a change in pressure. 

In the author's view, the most reliable method is simply to measure the 
hydrostatic head of liquid, using pressure tappings which are brought up 
toroom temperature to a suitable differential pressure gauge. At the low- 
temperature end, to eliminate hydrostatic head errors due to the liquid 
rising up the measuring tube, the tube must be arranged horizontally so 
that the liquid boils in the horizontal portion. Boiling can be ensured by 



34 



B. A. HANDS 



using a small heater if the natural heat leak from room temperature is not 
sufficient. Errors may occur because of unknown temperature gradients in 
the liquid and also in the vapour, whose density is often not negligible 
compared with that of the liquid, especially in helium systems. 

For liquid helium in the absence of strong magnetic fields, the super- 
conducting gauge is undoubtedly the most convenient and accurate, meas- 
uring level to within a few millimetres. The sensor consists of a length of 
Type II superconducting wire, which is heated so that it is superconducting 
below the liquid level, but normal above, so that the resistance is just 
proportional to the length of wire above the free surface. The state of the 
wire when in the vapour will again depend on the local heat transfer 
coefficient, but nevertheless a well-designed sensor appears to be unaffected 
by high velocity flows of cold gas. The heater is sometimes separate from 
the wire, sometimes the measuring current itself is sufficient. 

Many types of flowmeter have been used at cryogenic temperatures, with 
varied success, although it is usual to measure the flow at room temperature 
if possible. The low viscosity of the liquids, and their low density, means 
that turbine meters are not responsive to changes in flow rate, and also may 
be damaged by overspeeding due to the large gas flows during cooldown of 
the system; a bypass may therefore be necessary. If the liquid is near 
saturation, vapour may be formed in the throats of orifice plates and venturi 
meters unless the pressure differential is so low that it is difficult to measure. 
Again, the measuring equipment may be damaged during cooldown because 
of the large pressure differentials which may be developed. Ultrasonics and 
thermal anemometry have been used with some success, but the equipment 
is expensive and difficult to install in a cryogenic environment. Except for 
very small pipelines, the vortex-shedding meter may be the best type to 
use. 

A wide range of other instruments has been used in a cryogenic environ- 
ment. Generally, instruments used for room-temperature applications can 
be adapted, with a careful choice of materials, unless the measuring 
phenomenon itself is very sensitive to temperature or does not exist in 
the cryogenic temperature range. Many types of transistors will operate 
satisfactorily right down to liquid helium temperatures [1.16, 1.25], and this 
fact has been exploited in the design of many instruments. 



1.1 N. Kurti, 'Low Temperature Terminology', Proc. XIII Int. Congr. Refrig., Vol. I, f 
593-597 (Int. Inst. Refrig., 1973). 



1.2 N. Kurti, 'I 

1.3 Data kindl) 

1.4 E. K. Farid; 
Gastech 81 , 
1982). 

1.5 A. O. Tiscl 
1-10 (1966) 

1.6 E. F. Hamr 
(1980); A. J 
there a crisi 

1.7 C. H. Rode 
Cryog, Eng. 

1.8 L. J. Neurii 
pp. 32-43, 1 
'Supercondi 
53. 

1.9 B. J. Maddc 
Cryog. Eng 
conducting ; 
598, Genov; 

1.10 B.C. Belan 
in the U.S. 
(1975). 

1.11 E.B. Forsyl 
Cryogenics 1 

1.12 Cryogenics : 

1.13 R. I. Schen 
storage systt 
123-132 (19! 

1.14 T. Ohtsuka 

(1984)'. 

1.15 J. H.P.Wat 
presented at 

1.16 R. K. Kirscl 

1.17 H. M. Rose 

1.18 T. van Duk 
Edward Am 

1.19 S. J. Willian 
22, 129-201 

1.20 J. Matisoo, 
1980). 

1.21 The Times, j 

1.22 P. Le Piverl 
Engng Conf. 

1.23 B. A. Hand: 

1.24 B. A. Hand: 

1.25 B. Lengeler, 
genics 14, 43 



B. A. HANDS 

i temperature is not 
erature gradients in 
)ften not negligible 
systems. 

ic fields, the super- 
md accurate, meas- 
osists of a length of 
: is superconducting 
e resistance is just 
ce. The state of the 
local heat transfer 
ars to be unaffected 
imes separate from 
ficient. 

temperatures, with 
t room temperature 
low density, means 
/ rate, and also may 
during cooldown of 
the liquid is near 
e plates and venturi 
iifficult to measure. 
I cooldown because 
ed. Ultrasonics and 
, but the equipment 
mment. Except for 
)e the best type to 

cryogenic environ- 
re applications can 
;ss the measuring 
does not exist in 
istors will operate 
.16, 1.25], and this 



igr. Re frig., Vol. I, pp. 



1. A SURVEY OF CRYOGENIC ENGINEERING 35 

1.2 N. Kurti, 'From Cailletet and Pictet to microkelvin', Cryogenics 18, 451^*58 (1978). 

1.3 Data kindly supplied by R. M. Thorogood. 

1.4 E. K. Faridany, 'International trade in LNG: present projects and future outlook', Proc. 
Gastech 81 LNG/LPG Conference, pp. 21-35 (Gastech Ltd., Rickmansworth, England, 
1982). 

1.5 A. O. Tischler, "The impact of the space age on cryogenics', Adv. Cryog. Engng 11, 
1-10 (1966). 

1.6 E. F. Hammel, 'Helium: its past, present and future', Adv. Cryog. Engng 25, 810-821 
(1980); A. Francis, D. Keierleber and D. Swartz, 'Helium prospects for the future: is 
there a crisis?', Adv. Cryog. Engng 29, 9-17 (1984). 

1.7 C. H. Rode, 'Cryogenic system for a 100 km superconducting collider', Proc. 10th Int. 
Cryog. Engng Conf, pp. 760-770, Helsinki, Finland (1984). 

1.8 L. J. Neuringer, 'NMR in biology and medicine', Proc. 10th Int. Cryog. Engng Conf., 
pp. 32-43, Helsinki, Finland (1984); M. F. Wood, I. L. MacDougall and P. H. Winson, 
'Superconducting magnets for NMR imaging and in-vivo spectroscopy', ibid., pp. 44- 
53. 

1.9 B.J. Maddock and W. T. Norris, 'Superconductivity in electricity supply', Proc. 7th Int. 
Cryog. Engng Conf., pp. 245-259, London, England (1978); J. G. Steel, 'Super- 
conducting a.c. generators - a utility view', Proc. 8th Int. Cryog. Engng Conf., pp. 590- 
598, Genova, Italy (1980). 

1.10 B. C. Belanger, 'Superconducting and resistive cryogenic power transmission research 
in the U.S. - an opportunity for cryogenic innovation', Adv. Cryog. Engng 20, 1-22 
(1975). 

1.11 E. B. Forsyth, 'Cryogenic engineering for the Brookhaven power transmission project', 
Cryogenics 17, 3-7 (1977). 

1.12 Cryogenics 25, 50 (1985). 

1.13 R. I. Schermer et at., 'Design and operation of the 30 MJ superconducting magnetic 
storage system on the Bonneville Power Administration bus', Adv. Cryog. Engng 29, 
123-132 (1984). 

1.14 T. Ohtsuka and Y. Kyotani, 'Recent progress on superconducting magnetic levitation 
in Japan', Proc. 10th Int. Cryog. Engng Conf., pp. 750-759, Helsinki, Finland 
(1984). 

1.15 J. H. P. Watson, 'Status report on magnetic separation using superconducting magnets', 
presented at 10th Int. Cryog. Engng Conf., Helsinki, Finland (1984). 

1.16 R. K. Kirschman, 'Cold electronics: an overview', Cryogenics 25, 115-122 (1985). 

1.17 H. M. Rosenberg, The Solid State, 2nd edn, Clarendon Press (1978). 

1.18 T. van Duzer and C. W. Turner, Principles of Superconductive Devices and Circuits, 
Edward Arnold (1981). 

1.19 S. J. Williamson and L. Kaufman, 'Biomagnetism', /. Magnetism and Magn. Materials 
22, 129-201 (1981). 

1.20 J. Matisoo, 'The superconducting computer', Scientific American 282 (5), 38-53 (May 
1980). 

1.21 The Times, London, 1 December 1983, p. 19. 

1.22 P. Le Pivert, 'Cryosurgery: current issues and future trends', Proc. 10th Int. Cryog. 
Engng Conf., pp. 551-557, Helsinki, Finland (1984). 

1.23 B. A. Hands, 'Introduction to cryopump design', Vacuum 26, 11-16 (1976). 

1.24 B. A. Hands, 'Recent developments in cryopumping', Vacuum 32, 603-612 (1982). ; 

1.25 B. Lengeler, 'Semiconductor devices suitable for use in cryogenic environments', Cryo- 
genics 14, 439-447 (1974). 



36 



B. A. HANDS 



The most useful regular cryogenic publications are: 

Cryogenics, a journal published by Butterworth Scientific Ltd., Guildford, England. 

Advances in Cryogenic Engineering, which is published by Plenum Press and is the pro- 
ceedings of the biennial Cryogenic Engineering Conference and the concurrent International 
Cryogenic Materials Conference held in the USA. It is referred to in this volume as Adv. 
Cryog. Engng. 

Proceedings of the International Cryogenic Engineering Conference series (ICEC), pub- 
lished by Butterworth Scientific Ltd., Guildford, England, and predecessors. 

Proceedings of the LNG and GasTech Conferences, which contain information on devel- 
opments in LNG technology. 

IC SQUID, proceedings of the International Conferences on SQUIDs. 

International Institute of Refrigeration (IIR) conference proceedings. 

Proceedings of the Applied Superconductivity Conference series. 

General Bibliography 

In reverse order of publication: 

R. F. Barron, Cryogenic Systems, 2nd edn, Oxford University Press (1985). 

K. D. Williamson, Jr. and F. J. Edeskuty (eds), Liquid Cryogens Vol. 1: Theory and 

Equipment; Vol. 2: Properties and Applications, CRC Press (1983). 
A. Arkharov, I. Marfenina and Ye. Mikulin, Theory and Design of Cryogenic Systems, MIR 

Publishers (1981). 

G. K. White, Experimental Techniques in Low-Temperature Physics, 3rd edn, Clarendon 
Press (1979). 

A. C. Rose-Innes, Low Temperature Laboratory Techniques. The Use of Liquid Helium in 

the Laboratory, 2nd edn, English Universities Press (1973). 
C. A. Bailey (ed.), Advanced Cryogenics, Plenum Press (1971). 

G. G. Haselden (ed.), Cryogenic Fundamentals, Academic Press (1971). 

H. Weinstock (ed.), Cryogenic Technology, Boston Tech. Publ. (1969). 

R. H. Kropschot, B. W. Birmingham and D. B. Mann (eds), Technology of Liquid Helium, 

NBS Monograph 111 (1968). 
R. B. Scott, W. H. Denton and C. M. Nicholls (eds), Technology and Uses of Liquid 

Hydrogen, Pergamon Press (1964). 
J. H. Bell, Cryogenic Engineering, Prentice Hall (1963). 
R. W. Vance (ed.), Cryogenic Technology, John Wiley (1963). 

R. W. Vance and W. M. Duke (eds), Applied Cryogenic Engineering, John Wiley (1962). 
R. B. Scott, Cryogenic Engineering, Van Nostrand (1959). 



Bibliography of Specific Topics 

In alphabetical order of author: 

A. Barone and G. Paterno, Physics and Applications of the Josephson Effect, Wiley- 

Interscience (1982). 
N. R. Braton, Cryogenic Recycling and Processing, CRC Press (1980). 



ildford, England, 
i Press and is the pro- 
incunent International 
n this volume as Adv. 

x series (ICEC), pub- 
information on devel- 



(1985). 

s Vol. 1: Theory and 
ryogenic Systems, MIR 
j, 3rd edn, Clarendon 
te of Liquid Helium in 



71). 
,9). 

logy of Liquid Helium, 
•y and Uses of Liquid 



1. A SURVEY OF CRYOGENIC ENGINEERING 37 

British Cryogenics Council, Cryogenics Safety Manual - A Guide to Good Practice, 2nd edn, 

Mechanical Engineering Publications, Bury St. Edmunds (1982). 
j R. Bumby, Superconducting Rotating Electrical Machines, Clarendon Press (1983). 

A. J. Croft, Cryogenic Laboratory Equipment, Plenum Press (1970). 

B. Deaver and J. Ruvalds (eds), Advances in Superconductivity, Plenum Press (1983). 

T. van Duzer and C. W. Turner, Principles of Superconductive Devices and Circuits, Edward 
Arnold (1981). 

R. C. Ffooks, Natural Gas by Sea, Gentry Books, London (1979); Gas Carriers, Fairplay 

Press, London (1984). 
D. Fishlock (ed.), A Guide to Superconductivity, Macdonald-Elsevier (1969). 
S. Foner and B. B. Schwartz (eds), Superconducting Machines and Devices - Large Systems 

Applications, Plenum Press (1974). 
R. A. Haefer, Kryo-Vakuumtechnik: Grundlagen und Anwendungen, Springer-Verlag (1981) 

(English translation to be published by Oxford University Press). 
H. von Leden and W. G. Cahan, Cryogenics in Surgery, H. K. Lewis (1971). 
W L. Lom, Liquefied Natural Gas, Applied Science Publishers (1974). 
W. R. Parrish, R. O. Voth, J. G. Hust, T. M. Flynn, C. F. Sindt and N. A. Olien, Selected 

Topics on Hydrogen Fuel, NBS Special Publication 419 (1975). 
M. Rechowicz, Electric Power at Low Temperatures, Clarendon Press (1975). 

A. C. Rose-Innes and E. H. Rhoderick, Introduction to Superconductivity, 2nd ed., Pergamon 
Press (1978). 

R P Shutt (ed.), Bubble and Spark Chambers, Vol. 1, Academic Press (1967). 

B. B. Schwartz and S. Foner (eds), Superconductor Applications: SQUIDs and Machines, 
Plenum Press (1977). 

F. H. Turner, Concrete and Cryogenics, Cement and Concrete Ass., England (1979). 
M. N. Wilson, Superconducting Magnets, Clarendon Press (1983). 



Non-specialist Reading 

K. Mendelssohn, The Quest for Absolute Zero; the Meaning of Low Temperature Physics, 

Weidenfeld & Nicholson (1966). 
D. Wilson, Supercold, an Introduction to Low Temperature Technology, Faber & Faber 

(1979). 



g, John Wiley (1962). 



sephson Effect, Wiley- 

•0). 



ATTACHMENT B 



5 

I 

£ 



CRC Handbook 



OF 



Chemistry and Physi 

A Ready-Reference Book of Chemical and Physical Data 




EDITOR 

ROBERT C. WEAST, Ph.D. 

Vice President, Research, Consolidated Natural Gas Service Company, Inc. 
Formerly Professor of Chemistry at Case Institute of Technology 

ASSOCIATE EDITOR 

MELVIN J. ASTLE, Ph.D. 

Formerly Professor of Organic Chemistry at Case Institute of Technology 
Manager of Research at Glidden-Dwkee Division ofSCM Corporation 

In collaboration with a large number of professional chemists and physicists 
whose assistance is acknowledged in the list of general collaborators and in 
connection, with the particular tables or sections involved. 



CRC PRESS, Inc. 
2255 Palm Beach Lakes Blvd., West Palm Beach, Florida 33409 



Superconductivity* 

B.W. Roberts 

General Electric Research Laboratory, Schenectady, New York 

The following tables on superconductivity include superconductive properties of chemical 
elements, thin films, a selected list of compounds and alloys, and high-magnetic-field superconductors. 

The historically first observed and most distinctive property of a superconductive body is the 
near total loss of resistance at a critical temperature (TJ that is characteristic of each material. 
Figure 1(a) below illustrates schematically two types of possible transitions. The sharp vertical dis- 
continuity in resistance is indicative of that found for a single crystal of a very pure element or one 
of a few well annealed alloy compositions. The broad transition, illustrated by broken lines, 
suggests the transition shape seen for materials that are not homogeneous and contain unusual 
strain distributions. Careful testing of the resistivity limits for superconductors shows that it is less 
than 4x 10 ohm-cm, while the lowest resistivity observed in metals is of the order of 10" 13 
ohm-cm. If one compares the resistivity of a superconductive body to that of copper at room 
temperature, the superconductive body is at least 10 17 times less resistive. 




(c) 

Figure 1. PHYSICAL PROPERTIES OF SUPERCONDUCTORS 



(a) Resistivity versus temperature for a pure and perfect lattice (solid line). 
Impure and/or imperfect lattice (broken line). 

(b) Magnetic-field temperature dependence for Type-I or "soft" superconductors. 

(c) Schematic magnetization curve for "hard" or Type-II superconductors. 



The temperature interval AT C , over which the transition between the normal and superconductive 
states takes place, may be of the order of as little as 2 x 1 0 " 5 °K or several °K in width, depending on the 
material state. The narrow transition width was attained in 99.9999 percent pure gallium single crystals. 

A Type-I superconductor below T c , as exemplified by a pure metal, exhibits perfect diamagnetism 
and excludes a magnetic field up to some critical field H c , whereupon it reverts to the normal state as 
shown in the H-T diagram of Figure 1(b). 

The difference in entropy near absolute zero between the superconductive and normal states 
relates directly to the electronic specific heat, y: (S t -S.) T ^ 0 = - y T. 

The magnetization of a typical high-field superconductor is shown in Figure 1(c). The discovery 
of the large current-carrying capability of Nb 3 Sn and other similar alloys has led to an extensive 
study of the physical properties of these alloys. In brief, a high-field superconductor, or Type-II 
superconductor, passes from the perfect diamagnetic state at low magnetic fields to a mixed state and 
finally to a sheathed state before attaining the normal resistive state of the metal. The magnetic field 
values separating the four stages are given as H cl , H c2 , and H c3 . The superconductive state below 
H cl is perfectly diamagnetic, identical to the state of most pure metals of the "soft" or Type-I 

il Bureau of Standards, by Standard Reference Data Center on Superconductive 



E-85 



SUPERCONDUCTIVITY (Continued) 

Be t W een H , and H , a "mixed superconductive state" is found in which fluxons (a 

of careful measurement, it is possible to determine H cl , H c2 , ana n c3 . 

For superconductor, Hg, has entirely different magnetrzatron behav,or m h,gh 

r^JeCJ Z a verf few precisely stoid.iome.ric and wen annealed compounds are Type-I 
with the possible exceptions of vanadium and niobium. 

MetaUurgica, Aspect, TT>e sensitivity of -P«— ^tate ol aSoys^ 
pronounced and has been used in a ^^^^^Z^ other electron-scattering 
mechanical state, ^ , "7^^^g^lS2d the current^arrying capabilities in 

consideration to the metallurgical aspects of sample preparation. 

REFERENCES 

^sS-nauctive Materia, and Son, of Tneir Properties", P ro g ress * Cryo^cs, B.W. Roberts, Vo, IV, Heywood 
408 and 482, U.S. Government Printing Office, 1966 and 1969. 



E-86 



SELECTED PROPERTIES OF THE SUPERCONDUCTIVE ELEMENTS 

Conversion Factors 
Oe X 79.57 = A/m; katm X 1.013 X 10" = N/m 1 ; kb X 1.0 X 10" = N/m 3 



Element 


T C (K) 


H 0 (oersteds) 




7(mJraole"' dej 


Al 


1.175 


104.93 


420 


1.35 


Be 


0.026 






0.21 


Cd 


0.518, 0.52 


29.6 


209 


0.688 


Ga 


1.0833 


59.3 


325 


0.60 


Ga (0) 


5.90 , 6.2 


560 




GaOx) 


7.62 


950 






Ga(6) 


7.85 


815 






Hg(o) 


4.154 


411 


87, 71.9 


1.81 


Hgtf) 


3.949 


339 


93 


1.37 




3.405 


281.53 


109 


1.672 


Ir 


0.14 ,0.11 


19 


425 


3.27 


La (or) 


4.88 


808, 798 


142 


10.0, 11.3 


La (0) 


6.00 


1,096 


139 


11.3 


Mo 


0.916 


90,98 


460 


1.83 


Nb 


9.25 


1,970 


277, 238 


7.80 


Os 


0.655 


65 


500 


2.35 


Pa 


1.4 








Pb 


7.23 


803 


96.3 


3.0 


Re 


1.697 


188, 211 


415 


2.35 


Ru 


0.493 


66 


580 


3.0 


Sb 


2.6-2.7 






Sn 


3.721 


305 


195 


1.78 


Ta 


4.47 


831 


258 


6.15 


Tc 


7.73 ,7.78 


1,410 


411 


4.84, 6.28 


Th 


1.39 


159.1 


165 


4.31 


Ti 


0.39 


56, 100 


429,412 


3.32 


Tl 


2.332, 2.39 


181 


78.5 


1.47 


V 


5.43 ,5.31 


1,100, 1,400 


382 


9.82 


W 


0.0154 


1.15 


550 


0.90 


Zn 


0.875 


55 


319.7 


0.633 


Zr 


0.53 


47 


290 


2.78 


Zr(w) 


0.65 









Thin Films Condensed at Various Temperatures 
T C (K) 



1.18 — 5.7 
-03, ~9.6;6.5-10.6 a ; 10.2 b 
-2 — 5,6.11,6.154, 6.173 
0.53-0.91 
6.4-6.8, 7.4-8.4, 8.56 
3.43-4.5; 3.68-4.17 c 
5.0-6.74 
3.3-3.8,4-6.7 
6.2-10.1 
-2-7.7 
-7 



1.3 
2.64 
5.14-6.02 
<1.0-4.1 
0.77-1.48 



a With KC1. 

kftith Zn etioporphyrin. 
c In glass pores. 



E-87 



SELECTED PROPERTIES OF THE SUPERCONDUCTIVE ELEMENTS (Continued) 



Data for Elements Studied Under Pressure 



Element 


T C (K) 


Pressure 


As 


0.31-0.5 


220-140 kb 




0.2-0.25 


-140-100 kb 


Ball 


-1.3 


55 kb 


Ba III 


3.05 


85-88 kb 




-5.2 


>140 kb 


Bi II 


3.916 


25 katm 




3.90 


25.2 katm 




3.86 


26.8 katm 


Bi III 


6.55 


-37 kb 




7.25 


27-28.4 katm 


Bi IV 


7.0 


43, 43-62 kb 


BiV 


8.3, 8.55 


81 kb 


BiVI 


8.55 


90, 92-101 kb 


Ce 


1.7 


50 kb 


Cs 


-1.5 


>~125 kb 


Ga II 


6.24, 6.38 


>35 katm 


Gall' 


7.5 


>35 katm (P - 0) 


Ge 


4.85-5.4 


-120 kb 




5.35 


115 kb 


La 


~5.5-ll.93 


0 — 140 kb 


P 


4.7 


MOO kb 




5.8 


170 kb 


Pb II 


3.55, 3.6 


160 kb 


Sb 


3.55 


85 kb 




3.52 


93 kb 




3.53 


100 kb 




3.40 


-150 kb 


Sell 


6.75,6.95 


-130 kb 


Si 


6.7,7.1 


120 kb 


Sn II 


5.2 


125 kb 




4.85 


160 kb 


Sn III 






Tell 


2.05 


43 kb 




3.4 


50 kb 


TeHI 


4.28 


70 kb 


TelV 


4.25 


84 kb 


Tl, cub. 


1.45 


35 kb 


Tl, hex. 


1.95 


35 kb 


U 


2.3 


10 kb 


Y 


-1.2,-2.7 


120-170 kb 



From Roberts, B. W., Properties of Selected 
Superconductive Materials, 1974 Supplement, NBS 
Technical Note 825, U.S. Government Printing Office, 
Washington, D.C., 1974, 10. 



E-88 



SELECTED SUPERCONDUCTIVE COMPOUNDS AND ALLOYS 

All compositions are denoted on an atomic basis, i.e., AB, AB 2 , or AB 3 for compounds, unless 
noted. Solid solutions or odd compositions may be denoted as A I B 1 _ I or A Z B. A series of three or 
more alloys is indicated as A^B,,, or by actual indication of the atomic fraction range, such as 
A 0 -o.6 B i-o.4- Th e critical temperature of such a series of alloys is denoted by a range of values or 
possibly the maximum value. 

The selection of the critical temperature from a transition in the effective permeability, or the 
change in resistance, or possibly the incremental changes in frequency observed by certain techniques 
is not often obvious from the literature. Most authors choose the mid-point of such curves as the 
probable critical temperature of the idealized material, while others will choose the highest temperature 
at which a deviation from the normal state property is observed. In view of the previous discussion 
concerning the variability of the superconductive properties as a function of purity and other 
metallurgical aspects, it is recommended that appropriate literature be checked to determine the most 
probable critical temperature or critical field of a given alloy. 

A very limited amount of data on critical fields, H a , is available for these compounds and alloys; 
these values are given at the end of the table. 

SYMBOLS: n = number of normal carriers per cubic centimeter for semiconductor super- 
conductors. 







Crystal 






Crystal 


Substance 


T C ,°K 


structure 

typeft 


Substance 


T C ,'K 


structure 
typetf 


Ag.AljZn,.,-, 


0.5-0.845 




Al_ 0 . 8 Ge_ 02 Nb 3 


20.7 


A15 


Ag 7 BF 4 0 8 


0.15 


Cubic 


AlLa 3 


5.57 


DO,, 


AgBi 2 


3.0-2.78 




AI 2 La 


3.23 


C15 


Ag 7 F„. 25 N 0 . 75 O, 0 . 25 


0.85-0.90 




Al 3 Mg 2 


0.84 


Cubic, fx. 


Ag 7 FO„ 


0.3 


Cubic 


AlMo, 


0.58 


A15 


Ag 2 F 


0.066 




AlMo 6 Pd 


2.1 




AgM-o.jGao.,.0.7 


6.5-8 




A1N 


1.55 


B4 


Ag 4 Ge 


0.85 


Hex., c.p. 


Al 2 NNb 3 


1.3 


A13 


Ago.438Hgo.562 


0.64 


D8 2 


AlNb 3 


18.0 


A15 












D8,, 


Ago ,In 0 9 Te 






Al*NbJ_* 


12-17.5 


A15 


(n= 1.40x10") 


1.20-1.89 


Bl 


Alo.2 7 Nbo. 7 3-o.4 8 V 0 . 02 5 


14.5-17.5 


A15 


Ag0.2In0.sTe 






AlNb x V,_ x 


< 4-2- 13.5 




(n = 1.07x10") 


0.77-1.00 


Bl 


AlOs 


0.39 


B2 


AgLa(9.5 kbar) 


1.2 


B2 


AljOs 


5.90 




Ag,NO u 


1.04 


Cubic 


AlPb (films) 


1.2-7 




AfcPb,-, 


7.2 max. 




Al 2 Pt 


0.48-0.55 


CI 


Ag J Sn,_ :c (film) 


2.0-3.8 




Al 5 Re 24 


3.35 


A12 




1.5-3.7 




Al 3 Th 


0.75 


DO,, 


AgTe, 


2.6 


Cubic 


ALTi,V,_ x _, 


2.05-3.62 


Cubic 


AgThj 


2.26 


C16 


Alo.i„ 8 V 0 . 892 


1.82 


Cubic 


Ago.03Tlo.97 


2.67 




ALZn,., 


0.5-0.845 




Ago. 9 «Tl 0 . 06 


2.32 




AlZr 3 


0.73 


Ll 2 




0.5-0.845 




AsBiPb 


9.0 




Al(film) 


1.3-2.31 




AsBiPbSb 


9.0 




Al (1 to 21 katm) 


1.170-0.687 


Al 


As„ 33 InTe 067 
(n = 1.24x10") 






AlAu 4 


0.4-0.7 


Like A13 


0.85-1.15 


Bl 


Al 2 CMo 3 


10.0 


A13 


As 0 s InTe 0 5 






Al 2 CMoj 


9.8-10.2 


A13 + trace 


(n = 0.97x10") 


0.44-0.62 


Bl 


Al 2 CaSi 




2nd phase 


■ As 0 50 Ni 0()<i Pd 0 4 4 


1.39 


C2 


5.8 




AsPb 


8.4 




A1 o.i3iCr 0 088 V 07ai 
AlGe 2 

AV 5 Ge 05 Nb 


1.46 


Cubic 


AsPd 2 (low- 






1.75 




temperature phase) 


0.60 


Hexagonal 


12.6 


A15 


AsPd 2 (high-temp, phase) 


1.70 


C22 



ttSee key at end of table. 



E-89 



SELECTED SUPERCONDUCTIVE COMPOUNDS AND ALLOYS (Continued) 

















I 




T„°K 


Crystal 






s^ctule 




Substance 


structure 
typeft 


Substance 


T e ,°K 


■ 


' 

B i o3 Pbo,iSn 0 .i9 






C 0 «Mo c s< 


1.3 


Bl 




(weight fractions) 


8.5 




C0.5Mo.Nb,., 


10.8-12.5 


Bl 




B i 0 . 5 Pb.. 25 Sn 0 .25 


8.5 




Co. 6 Mo 4 8 Si 3 


7.6 


D8 8 




BiPd 2 


4.0 




CMo 0 . 2 Ta 0 .„ 


7.5 


Bl 




Bio.«P d o« 


3.7-4 


Hexagonal, 


CMo 0 J Ta o j 


7.7 


Bl 


al 






ordered 


CMo 0 7J Tao „ 


8.5 


Bl 




BiPd 


3.7 


Orthorhombic 


CMo 08 Ta 0 . 2 


8.7 


Bl 




Bi 2 Pd 


1.70 


Monoclinic, 


CMo 0 . 8 jTa 0 15 


8.9 


Bl 


al 




a-phase 


CMo.Ti,., 


10.2 max. 


Bl 


al 


Bi 2 Pd 


4.25 


Tetragonal, 


CMo„ „Ti 0 17 


10.2 


Bl 






0-phase 


CMo.V,., 


2.9-9.3 


Bl 




BiPdSe 


1.0 


C2 


CMo.Zr,., 


3.8-9.5 


Bl 


22 Re 


BiPdTe 


1.2 


C2 


C 0 .,-o.9N 0 ,-oiNb 


8.5-17.9 






BiPt 


1.21 


B8, 


Co-o.saN.-o.sjTa 


10.0-11.3 






BiPtSe 


1.45 


C2 


CNb (whiskers) 


7.5-10.5 






BiPtTe 


1.15 


C2 


C 0 . 9B4 Nb 


9.8 


Bl 


Bi 2 Pt 


0.155 


Hexagonal 


CNb (extrapolated) 


-14 




22 Re 


Bi 2 Rb 


4.25 


C15 


Co.7-i.oNb 0 .j_o 


6-11 


Bl 


! BiRe 2 


1.9-2.2 




CNb 2 


9.1 




BiRh 


2.06 


B8, 


CNb x Ta,. x 


8.2-13.9 




22 Re 


Bi 3 Rh 


3.2 


Orthorhombic, 


CNb.Ti,., 


< 4.2-8.8 


Bl 


al 






like NiB 3 


CNb 0 . 6 _ 0 ,W 04 _ 01 


12.5-11.6 


Bl 




Bi 4 Rh 


2.7 


Hexagonal 


CNbo^.o^Zro^o., 


4.2-8.4 


Bl 




BijSn 


3.6-3.8 




CRb, (gold) 


0.023-0.151 


Hexagonal 




BiSn 


3.8 




CRe 0 .oi-o.o 8 W 


1.3-5.0 




Bi>, 


3.85-4.18 




CRe 00t W 


5.0 






Bi,Sr 


5.62 


Ll 2 


CTa 


~ 1 1 (extrap- 






BijTe 


0.75-1.0 






olated) 






BijTlj 


6.4 




C 0 , 87 Ta 


9.7 






Bio.jsTlo.T* 


4.4 


Cubic, 


C 0 .8*8-0.987Ta 


2.04-9.7 










disordered 


CTa (film) 


5.09 


Bl 




Bio. 26 Tl 0 . 74 


4.15 


Ll 2 , ordered? 


CTa 2 


3.26 


L'3 




Bi 2 Yj 


2.25 




CTa 0 4 Ti 0 6 


4.8 


Bl 




Bi 3 Zn 


0.8-0.9 




CTa^o^Wo-os 


8.5-10.5 


Bl 




Bi 03 Zr 07 


1.51 




CTa 02 -o9Zr 08 _ 01 


4.6-8.3 


Bl 




BiZr 3 


2.4-2.8 




CTc (excess C) 


3.85 


Cubic 




CCs, 


0.020-0.135 


Hexagonal 


CTi 0 .j.o.7W 0 .s_o.j 


6.7-2.1 


Bl 




C,K(gold) 


0.55 




CW 


1.0 






CGaMo 2 


3.7-4.1 


Hexagonal, 


CW 2 


2.74 


L'3 




CHf 0J Mo o 5 




H-phase 


CW 2 


5.2 


Cubic, f.c. 




3.4 


Bl 


Calr 2 


6.15 


C15 


ase 


CHf 0 . 3 Mo 0 , 


5.5 


BI 


Ca.OjSr^Ti 








CHf„ „Mo 0 75 


6.6 


Bl 


(n = 3.7-11.0x10") 


<0. 1-0.55 






CHf 0 ,Nb 0 3 ' 


6.1 


Bl 


Ca 0 .,O 3 W 


1.4-3.4 


Hexagonal 




CHf 06 Nb 04 


4.5 


Bl 


CaPb 


7.0 




CHf 0 3 Nb 0 5 


4.8 


Bl 


CaRh 2 


6.40 


C15 




c Hf 0 4Nb 06 


5.6 


Bl 


Cdo.3.0.5Hg„. 7 -0. 5 


1.70-1.92 




CHf OJ5 Nb 075 


7.0 


BI 


CdHg 


1.77, 2.15 


Tetragonal 


.mbic 


CH fo 2 Nb 0 „ 
CHfo. 9 -„. 1 Ta 0 ,_ 0 . 9 


7.8 


Bl 


Cd 00 o75-oo5ln,-, 


3.24-3.36 


Tetragonal 




5.0-9.0 


Bl 


Cd 0 ., 7 Pb 0 o3 


4.2 






Ck (excess K) 


0.55 


Hexagonal 


CdSn 


3.65 




al, . 


C,K 


. 0.39 


Hexagonal 


Cd 017 Tlo. 8 3 


2.3 






C o.4olo.«Mo 060 _ 056 


9-13 




Cd 0ie Tl O82 








CMo 
CMo 2 


6.5, 9.26 




CeCo 2 


0.84 


C15 




12.2 


Orthorhombic 


CeCo 167 Ni 0 .33 


0.46 


CI5 



ttSee key at end of table. 



SELECTED SUPERCONDUCTIVE COMPOUNDS AND ALLOYS (Cortfaued) 



ubstance 
sance 


T t , K 


Crystal 
structure 

'ypeft 


Substance 


T C ,°K 


Crystal 
structure 

'ypetf 




GePt 


040 




InSb 


2.1 




Ge 3 Rh 5 




Ortnorhornbic, 


(InSbV„_ 010 Sn 0 . 05 . 090 










related to 


(various heat treatments) 


3.8-5.1 








InNij 


(InSb) 0 _ 0 ; 07 Sn 1 _ 0 . M ' 


3.67-3.74 




Ge 2 Sc 






In 3 Sn 


~5.5 




Ge 3 Te 4 






In^Sn,., 


3.4-7.3 




(n — ] 06 x 10 22 ) 


. - .80 


Rhombohedral 


In o.82-i T e 






/ 1 o% £4 v m2o% 






(n = 0.83-1.71 x 10 22 ) 


1.02-3.45 


Bl 


(n = o.j — 04 x 1 u ) 




Bl 


Ini.oooTe,. 002 


3.5-3.7 


Bl 


GeV 3 




A15 


In 3 Te 4 






GejYy 




C ' 


(n = 0.47 x 10 22 ) 


1.15-1.25 


Rhombohedral 




24 




In^Tl, _ x 


2.7-3.374 






7 28 


!°* * c " 




3.223 








Cubic, b.c. 




2.760 








Cubic, b.c. 


In 0.78-0.69Tlo.22-0.31 


3.18-3.32 


Tetragonal 






Cubic, b.c. 


In 0 .69-0.62Tlo.31-o.3B 


2.98-3.3 


Cubic, f.c. 


H 0 .08 Ta 0.92 




Cubic, b.c. 


Ir 2 La 


0.48 


C15 


H 0 .0* Ta 0.96 




Cubic, b.c. 


Ir 3 La 


2.32 


D10 2 


HfN 0 .989 


6.6 


BI 


Ir 3 La 7 


2.24 


D10 2 


Hf 0 -0.5 Nb l-0.3 


8.3-9.5 


A2 


Ir 5 La 


2.13 




Hf 0 .75 Nb 0.25 


>4.2 




Ir 2 Lu 


2.47 


C15 


HfOs 2 


2.69 


C14 


Ir 3 Lu 


2.89 


C15 


HfRe 2 


4.80 


C14 


IrMo 


<1.0 


A3 


Hfo.u e 0-86 




A12 


IrMo 3 


8.8 


AI5 


Hlo.99 -0.96*^0.01 -0.04 






IrMo 3 


6.8 


D8» 


orv" 0 ' 55 ^ 1 " 0 ' 45 






IrNb 3 


1.9 


A15 


2 






Ir 04 Nb 06 


9.8 


D8, 




3.14-4.55 




lr„ J7 Nb 0(i 3 


2.32 


D8> 


Hgln 


3.81 




IrNb 


7.9 


D8, 


Hg 2 K 


1.20 


Orthorhombic 


Ir 002 Nb 3 Rh 0 .9, 


2.43 


A15 


H^K 






Ir 0 0J Nb 3 Rh 0 95 


2.38 


A15 




^77 






5.5 


E9 3 


Hg e K 


1 7 2 




Iro.265Oo.035Tio.s5 


2.30 


E9 3 




i'Io 


Hexagonal 


Ir.Os, _ x 


0.3-0.98 




gj a 


1.62 


Hexagonal 




(max.)-0.6 






3.05 




IrOsY 


2.6 


C15 


H 5f -* 


4.14-7.26 




Ifi.sOso.s 


2.4 


C14 




4.2 




Ir 2 Sc 


2.07 


as 


H Tl 

H T,'~* 


2.30-4.109 




Ir 25 Sc 


2.46 


as 




3.86 




IrSn 2 


0.65-0.78 


a 


Ho' La' 


9M 6 'lO 4 




Ir 2 Sr 


5.70 


C15 


InLa 3 ' 




Ll 2 


Iro.5Te 0 . 5 


~3 




InLa 3 (0-35 kbar) 


07< in « 
9.75-10.55 




IrTe 3 


1.18 


C2 
»/ 


In l-0.86Mgo.o.,» 


3.395-3.363 




IrTh 


<0.37 


InNb 3 






Ir 2 Th 


6.50 


C15 


^(high pressure and temp.) 


4-8, 9.2 


A15 


Ir 3 Th 


4.71 






18.0-18.19 


A15 


Ir 3 Th 7 


1.52 


D10 2 


I ° Nh 7 


6.4 




Ir 5 Th 


3.93 


D2, 


"o.nOjW 


< 1.25-2.8 


Hexagonal 


IrTi 3 


5.40 


A15 


^0.95-0.85Pb 0 .O5-o,13 


3.6-5.05 




IrV 2 


1.39 


A15 




3.45-4.2 




IrW 3 


3.82 




InPb 8 "' 1 0 02 " 009 


6.65 










InPd 


0.7 


B2 


Ir 2 Y 8 


2.18, 1.38 


C15 


InSb (quenched from 






Ir 0 69 Y 031 


1.98, 1.44 


C15 


170 kbar into liquid N 2 ) 


4.8 


Like A5 


Ir 0 .7oY 0 ' 3 o 


2.16 


CIS 



E-93 



SELECTED SUPERCONDUCTIVE COMPOUNDS AND ALLOYS (Continued) 



Substance 


T C ,°K 


Crystal 
structure 
typeft 


Substance 


T„°K 


Crystal 
structure 
typeft 




NbS 2 


5.0-5.5 


Hexagonal, 


Os 2 Zr 


3.0 


C14 




three-layer 


Os^Zr,., 


1.50-5.6 








type 


PPb 






Nb 3 Sb 0 _o.7Sn,-o. 3 


6.8-18 


A15 


pp d 3 . 0 - 3 . 2 


< 0.35-0.7 


DO,, 


NbSe 2 


5.15-5.62 


Hexagonal, 


P 3 Pd 7 (high temperature) 


1.0 


Rhombohedral 




NbS 2 type 


P 3 Pd 7 (low temp.) 


0.70 


Complex 


Nb,-i.o5Se2 


2.2-7.0 


Hexagonal, 


PRh 


1.22 








NbS 2 type 


PRh 2 


1.3 


CI 


Nb 3 Si 


1.5 


Ll 2 


PW 3 


2.26 


DO, 


Nb 3 SiSnV 3 


4.0 




Pb 2 Pd 


2.95 


C16 


Nb 3 Sn 


18.05 


A15 


Pb 4 Pt 


2.80 


Related to C16 


Nb 0 . 8 Sn 0 . 2 


18.18, 18.5 


A15 


PbjRh 


2.66 


C16 


Nb.Sn.-^nlm) 


2.6-18.5 




PbSb 


6.6 




NbSn 2 


2.60 


Orthorhombic 


PbTe (plus 0.1 w/o Pb)t 


5.19 




Nb 3 Sn 2 


16.6 


Tetragonal 


PbTe (plus 0.1 w/o Tl)t 


5.24-5.27 




NbSnTa 2 


10.8 


A15 


PbTl 027 


6.43 




Nb 2 SoTa 


16.4 


A15 


PbTl 0 . 17 


6.73 




Nbj. 5 SnTa 0 . 5 


17.6 


A15 


p bTl 0 . 12 


6.88 




Nb 2 75 SnTa 0 . 25 


17.8 


A15 


Pbn 0075 


6.98 




Nb 3l SnTa 3(1 _ x) 


6.0-18.0 




PbTl 0 . 04 


7.06 




NbSnTaV 


6.2 


A15 


Pb,- 0 . 26 Tl 0 - 0 . 74 


7.20-3.68 




Nb 2 SnTa 0 . 5 V 0 . 5 


12.2 


A15 


PbTl 2 


3.75-4.1 




NbSnV 2 


5.5 


A15 


Pb 3 Zr 5 


4.60 


D8 8 


Nb 2 SnV 


9.8 


AI5 


PbZr 3 


0.76 


AI5 


Nb 2 . 5 SnV 0 . 5 


14.2 


A15 


Pd 0 . 9 Pto.,Te 2 


1.65 


C6 


Nb,Ta,_, 


4.4-9.2 


A2 


Pdo.ojRUo 05 Zr 0 9 


~9 




NbTc 3 


10.5 


A12 


Pd 22 S (quenched) 


1.63 


Cubic 


Nb^Ti,., 


0.6-9.8 




PdSb 2 


1.25 


C2 


Nb 0 . 6 Ti 0 . 4 


9.8 




PdSb 


1.50 


B8, 


Nb.U,., 


1.95 max. 




PdSbSe 


1.0 


C2 


Nb 0 . 88 V 0 . 12 


5.7 


A2 


PdSbTe 


1.2 


C2 


Nb 0 . 75 Zr 0 . 25 


10.8 




Pd«Se 


0.42 


Tetragonal 


Nb 0 . 66 Zr 0 . 33 


10.8 




Pd 6 _ 7 Se 


0.66 


Like Pd 4 Te 


Ni,, 3 Th 0 7 


1.98 


D10 2 


Pd 28 Se 


2.3 




NiZr 2 


1.52 




Pd^Se,., 


2.5 max. 




Ni..,Zr 0 . 9 


1.5 


A3 


PdSi 


0.93 


B31 


O3Rbo.27-o.29W 


1.98 


Hexagonal 


PdSn 


0.41 


B31 


0 3 SrTi 






PdSn 2 


3.34 




(n = 1.7-12.0x10") 


0.12-0.37 




Pd 2 Sn 


0.41 


C37 


OjSrTi 






Pd 3 Sn 2 


0.47-0.64 


B8 2 


(n = 10' 8 -10 21 ) 


0.05-0.47 




PdTe 


2.3, 3.85 


B8, 


0 3 SrTi 






P<JTe 102 - 108 


2.56-1.88 


B8, 


(n = ~ IO 20 ) 


0.47 




PdTe 2 


1,69 


C6 


OTi 


0.58 




PdTe 2 ., 


1.89 


C6 


O 3 Sr 008 W 


2-4 


Hexagonal 


PdTe 2 3 


1.85 


C6 


OsTlo.aoW 


2.0-2.14 


Hexagonal 


Pd, ,Te 


4.07 


B8, 


OV 3 Zr 3 


7.5 


E9 3 


PdTh 2 


0.85 


C16 


OW 3 (film) 


3.35, 1.1 


A15 


Pd 01 Zr 09 


7.5 


A3 


OsReY 


2.0 


C14 


PtSb 


2.1 


B8, 


Os 2 Sc 


4.6 


C14 


PtSi 


0.88 


B31 


OsTa 


1.95 


A12 


PtSn 


0.37 


B8, 


Os 3 Th 7 


1.51 


D10 2 


PtTe 


0.59 


Orthorhombic 




0.9-4.1 




PtTh 


0.44 






~3 










Os 2 Y 


4.7 


C14 


PtjTh' 


3.13 




Wo denotes weight percent. 


ftSee key at end of table. 









SELECTED SUPERCONDUCTIVE COMPOUNDS AND ALLOYS (Condoned) 







Crystal 






Crystal 


Substance 


T„"K 


structure 
typeft 


Substance 


T C ,°K 


structure 


PtTi 


0.58 


A15 


Ru 2 Y 


1.52 


C14 


Pt o02 U 0 .98 


0.87 


l-phase 


Ru 2 Zr 


1.84 


CI4 




1.36 


A15 




5.7 


A3 


ply 2 5 


2.87-3.20 


A15 


SbSn 


1.30-1.42, 


Bl or distorted 


ptv' 


1.26 


A15 




1.42-2.37 


Bl 


p» \L 


04^2 7 


Al 


SbTi 3 


5.8 


A15 


pt w 0 5 






Sb 2 Tl 7 


5.2 






0.90 




Sbo.oi-o.ojVo.,9-0.97 


3.76-2.63 


A2 


ptV 


1.57, 1.70 


C15 


SbV 3 


0.80 


A15 


PtV 


0.82 


D10, 


SijTh 


3.2 


C c , oc-phase 


PtZr' 


3.0 


A3 


SijTh 


2.4 


C32, /J-phase 


Re Ta 


1.46 


A12 


SiV, 


17.1 


AI5 


Re° Ti 0 


6.60 


A12 


Sio^VjAl,,, 


14.05 


AI5 


ReTi 3 






Si 0 . 9 VjB 0 ., 


15.8 


A15 


* v* 


4.52 


D8 t 


Sio.sVjCo., 


16.4 


A15 


Re° 7S V° J4 


6.8 


A3 


SiV 2 . 7 Cr 0 . 3 


11.3 


A15 


R 0 9 ^ v ° 08 


6.0 




Sio^VjGeo., 


14.0 


AI5 


Re° 6 W° 4 


5.12 


D8» 


SiV 2 . 7 Mo 0 . 3 


11.7 


A15 


Re°Y 0 5 


1.83 


C14 


SiV 2 . 7 Nb 0J 


12.8 


A15 




5.9 


C14 


SiV 2 ' 7 Ru 0 'j 


2.9 


A15 


Re^Zr 


7.40 


A12 


SiV 2 ,Ti 0 3 


10.9 


A15 


Rh S 


5.8 


Cubic 


SiV 27 Zr 03 


13.2 


A15 


Rh_ 024 Sc_ 0 . 7(S 


0.88, 0.92 




Si,W 3 


2.8, 2.84 


A15 




6.0 max. 




Sno.174-o.104Tao.s26-o.896 


6.5-<4.2 


Rh*Sr' * 




C15 


SnTa 3 


8.35 


A15, highly 


Rh 04 Ta 06 


2.35 


D8 t 






ordered 
A15, partially 




1.51 


C2 


SnTa 3 


6.2 


RhJ^T 










ordered 
A15 


RhTe C ° 33 


151 max 




SnTaV 2 


2.8 


RhTh ' * 


0.36 


B / 


SnTa 2 V 


3.7 


A15 


Rh Th 




D10 2 


Sn.Te,., 






. * 7 


1 07 




(n = 10.5-20x10") 


0.07-0.22 


Bl 


Rh Ti 


2.25-3.95 




Sn.Tl,., 


2.37-5.2 




Rh' U* 


0.96 




SnVj 


3.8 


A15 


Rhv" 


0.38 


A15 




2.87--1.6 


A2 


RhW 


~3.4 


A3 


Ta « 025^975° 98 0 943 


1.3 


Hexagonal 


RhY 


0.65 




Ta 0 05 Ti 0 95 


2.9 


Hexagonal 


RhjYj 


1.48 




Ta 0 03 -o. 73 V 0 .o95-o.25 


4.30-2.65 


A2 




1.07 


C15 


Ta 0 .8-iW 0 .2-(, 


1.2-4.4 


A2 


RhjY 


0.56 




Tc 01 _ 0 «W 0 ,. 06 


1.25-7.18 


Cubic 


RhZr 2 


10.8 


Q6 


TCo.5oWo.jo 


7.52 


01 plus a 


Rho oos^r (annealed) 


5.8 




Tc 0 6oW 0 «o 


7.88 


a plus a 




2.1-10.8 




Tc 6 Zr 


9.7 


A12 


Rh! °Zi^ T> ° 53 


9.0 


Hexagonal, c.p. 


Th 0 _ 0 55 Y 1 _o4 5 


1.2-1.8 




RuSc r ° ' 


1.67 


C14 


Tio.7oVo. 3 o 


6.14 


Cubic 


Ru 2 Th 


3.56 


C15 


Ti,V,_ x 


0.2-7.5 




RuTi 


1.07 


B2 


Tio.5Zr 0 .5 (annealed) 


1.23 




Ru 0 . 05 Ti 0 . 95 


2.5 




Ti 0 5 Zr 0 . 5 (quenched) 


2.0 




R"o.iTi 0 9 


3.5 




V 2 Zr 


8.80 


C15 


Rujio 6 V, 


6.6 max. 




V 0 1*2*0 74 


*5.9 




RU045V0.55 


4.0 


B2 


W 2 Zr 


2.16 


C15 


RuW 


7.5 


A3 









ttSee key at end of table. 



'See "Hj 



E-96 



SELECTED SUPERCONDUCTIVE COMPOUNDS AND ALLOYS (Continued) 
CRITICAL FIELD DATA 



Substance 


ff c , 
oersteds 


Ag 2 F 


2.5 


Ag 7 NO M 


57 


AI 2 CMo 3 


1,700 


BaBij 


740 


Bi 2 Pt 


10 


Bi 3 Sr 


530 


B15TI3 


>400 


CdSn 


>266 


CoSi 2 


105 


Cr 0 ,Ti 0 3 V 0 6 


1,360 


^,.0,4^-0.14 


272.4-259.2 







Substance 


oersteds 


InSb 


1,100 


In.Tl,., 


252-284 


In„ 8 T1 0 2 


252 


Mg-o.47Tl-0.53 


220 


Mo 0 16 Ti 0 84 


<985 


NbSn 2 


620 


PbTl 0 . 27 


756 


PbTl 0 . 17 


796 


PbTl 012 


849 


PbTl 0 075 


880 


PbTl 0 04 


864 



KEY TO CRYSTAL 



"Struck- 
turberichl" 
type* 


Example 




Al 


Cu 


Cubic, f.c. 


A2 


W 


Cubic, b.c. 


A3 


Mg 


Hexagonal, close packed 


A4 


Diamond 


Cubic, f.c. 


A5 


White Sn 


Tetragonal, b.c. 


A6 


In 


Tetragonal, b.c. (f.c. cell 






usually used) 


A7 


As 


Rhombohedral 


A8 




Trigonal 


A10 


Hg 


Rhombohedral 


A12 


o-Mn 


Cubic, b.c. 


A13 






A15 


"fl-W (W0 3 ) 




Bl 




Cubic fc 




CsCl 


Cubic 


B3 


ZnS 


Cubic 


B4 


ZnS 


Hexagonal 


B8, 


NiAs 


Hexagonal 


B8 2 


Ni 2 In 


Hexagonal 


B10 


PbO 


Tetragonal 


Bll 


y-CuTi 


Tetragonal 


B17 


PtS 


Tetragonal 


B18 


CuS 


Hexagonal 


B20 


FeSi 


Cubic 


B27 


FeB 


Orthorhombic 


B31 


MnP 


Orthorhombic 


B32 


NaTl 


Cubic, f.c. 


B34 


PdS 


Tetragonal 


B / 


5-CrB 


Orthorhombic 


B, 


MoB 


Tetragonal, b.c. 


B, 


WC 


Hexagonal 


B ; 


y-MoC 


Hexagonal 


CI 


CaF 2 


Cubic, f.c. 


ci 4 


MgAgAs 


Cubic, f.c. 


C2 


FeS 2 


Cubic 


C6 


Cdl 2 


Trigonal 


Cllb 


MoSi 2 


Tetragonal, b.c. 


C12 


CaSi 2 


Rhombohedral 


C14 


MgZn 2 


Hexagonal 


C15 


Cu 2 Mg 


Cubic, f.c. 



•See "Handbook of Lattice Spacing and Structures of Metals", W.B. : 



TYPES 



k 

turoeric^ I 


xampe 




C15 4 










T C 

Tetragonal, b.c. 




b« 2 




C22 








PhO 


Orthh b' 
Ortnornom ic 




Am 


exagona 


rv, 


M N' 










C49 


ZS 


Orthorhombic 














DO 


B'F 


Cubic, f.c. 








do" 


Na* As 


He^ r onaT biC 


do" 


Ni 3 Sn 


Hexagonal 


DO 20 


NiAl 3 


Orthorhombic 


D0 22 


TiAl 3 


Tetragonal 


DO, 


Ni 3 P 


Tetragonal, b.c. 


Dl 3 


Al 4 Ba 


Tetragonal, b.c. 


Die 


PtSn 4 


Orthorhombic 


D2, 


CaB 6 


Cubic 


D2 e 


MnU 6 


Tetragonal, b.c. 


D2, 


CaZn 5 


Hexagonal 


D5 2 


La 2 0 3 


Trigonal 


D5 8 


Sb 2 S 3 


Orthorhombic 


D7 3 


Th 3 P« 


Cubic, b.c. 


D7 t 


Ta 3 B 4 


Orthorhombic 


D8, 


Fe 3 Zn 10 


Cubic, b.c. 


D8 2 


Cu 5 Zn 8 


Cubic, b.c. 


D8 3 


Cu 9 Al 4 


Cubic 


D8„ 


Mn 5 Si 3 


Hexagonal 


D8 k 


CrFe 


Tetragonal 


D8, 


Mo 2 B 5 


Rhombohedral 


D10 2 


Fe 3 Th 7 


Hexagonal 


E2, 


CaTi0 3 


Cubic 


E9 3 


Fe 3 W 3 C . 


Cubic, f.c. 


Ll 0 


CuAu 


Tetragonal 


Ll 2 


Cu 3 Au 


Cubic 


L' 2( , 


ThH 2 


Tetragonal, b.c. 


L'3 


Fe 2 N 


Hexagonal 



,n. Vol. I, Pergamon Press, 1958, p. 79. and Vol. II, Pergamon Press, 1967, p. 



E-97 



HIGH CRITICAL MAGNETIC-FIELD SUPERCONDUCTIVE COMPOUNDS AND ALLOYS (O 



Nb 

Nb (unstrained) 

Nb (strained) 

Nb (cold-drawn wire) 

Nb (film) 

NbSc 

NbjSn 



OjSrTi 
OjSrTi 

PbSb, » ; . (quenched) 
PbSb, wl . (annealed) 
PbSb 2 s »/• (quenched) 
PbSb 2 , „„ (annealed) 
Pb„.7iSn 0129 
Pb„.,„Sn 00 , 5 
Pb,- 0 2 «T1 0 . 0 74 
PbTl 0 17 
R«o 26W„ 74 



Ta 05 Nb 05 
Tao.^.oTio.,, 
Ta„. 5 Ti 0 . 5 
Te 

Tc x W, 
Ti 

Tio^Vo.,, 
Ti 0 77 3 V 0 JJ5 
Ti<,. 613 V 0 . 3 , 5 
Tio. 5 ,.V 0 . 4 , 4 
Tio..,5V 0 . 5 » 5 

Tio.o.V,,.,, 



0.4-1.1 
1.1-1.8 
1.25-1.92 



0.425 
0.325 
0.275 
0.090 



0.029* 
0.024* 

0.050 



0.227 
0.185 
0.165 



fTemperature 
•Extrapolated. 
"Linear extrapolation. 
**• Parabolic extrapolation. 



2.020 
1.710 
3-5.5 



>0.7 
>2.3 
>0.7 



E-99 



j TABLES OF PROPERTIES OF SEMICONDUCTORS 
l Compiled by Dr. Brian Randall Pamplin 

/ 



E-100