An analytical study was made of the feasibility of using an MHD- augmented arc as the primary component of a large reentry vehicle test facility. Computer studies of the performance of MHD accelerator channels were made for systems having channel input power of 50 MW to 1,700 MW. It was determined that complete simulation of reentry conditions is not possible in a single extended- flow facility. The studies showed, however, that very large increases in performance over existing arc facilities could be attained by use of MHD augmentation, provided, however, that several very difficult design problems could be solved. The most critical problem area was identified as that of maintaining the design integrity of the magnetic-field walls of the channel, which requires that a high level of electrical insulation be retained under a heating load of up to 10 sq cm. Only a marked increase in high-temperature materials technology would permit the use of uncooled refractories for these walls. The possibility of using film cooling for these walls was explored and it was found that, in addition to a substantial increase in complexity, such an approach would result in significant reductions in performance and efficiency of the MHD channel.