Realizing the potential of photoconductive switching for HPM applications

Recent systems developments that take advantage of avalanche-mode photoconductive switching have led to major breakthroughs in high power microwave (HPM) generator performance. The best example is the GEM 2 demonstrator system developed for the Air Force. The delivered system, using over 800 BASS{trademark} photoconductive switches arrayed in 72 identical modules firing with 10-psec accuracy, produces 1 GW of peak power and an effective radiated power of over 100 GW. The authors are now looking beyond GEM 2 at continuing major improvements. The simplicity and flexibility of modular designs, such as GEM 2, facilitates new configurations and encourages timely inclusion of additional innovations. Concepts under consideration range from miniaturized generators, taking fall advantage of the solid-state approach, to generator arrays considerably larger than GEM 2. Power conditioning and antenna sizes dominate present systems. Optical triggering subsystems based on semiconductor lasers, though relatively small, are still much larger than the corresponding BASS-based microwave generators. Work underway is aimed at these limitations. Several candidate solid-state switching approaches for pulse charging, for example, offer many additional benefits. Further, commercial developments have resulted in extraordinarily compact laser drivers to effect similar size and weight benefits to the Optical Trigger Subsystem.