Researchers at Los Alamos National Laboratory (LANL) are developing a new solid-state high-voltage Marx modulator for the generation of pulsed power. The initial application of the LANL modulator is to provide power to a magnetron that requires a 46-kV, 160-A, 5- s rectangular pulse. This modulator technology is also being developed for other applications, including portable millimeter wave sources, a beam energy corrector for induction accelerators, and space-based power systems. The LANL solid-state modulator has several benefits, including wave shape control, switch protection, efficiency, and compactness. The present paper describes this source technology and its design.