Scaled-Up LGPT (Laser Gated and Pumped Thyristor) Devices at KrF IFE (Inertial Fusion Energy) Operating Parameters

The LGPT devices are performing to specification in both di/dt and action per unit area, and have demonstrated durability beyond 10⁷ shots at system rep-rate (5-7 pps). The present devices represent minimum-size building-block units for use in near and far-term KrF IFE laser drivers, and they employ on-board optical sources for direct illumination of the silicon thyristor structure. Typical operating parameters for the devices undergoing durability tests are 16.4 kV forward blocking, peak currents of 1.5 to 2.5 kA per cm², for an 800 ns pulsewidth, and di/dt´s of up to 25 kA/usec/cm². Two practical methods are there for directly illuminating the silicon: through the electrode surfaces as has been practiced for the past 5 years, and a new method employing the laser bar arrays in a side-shine geometry. The nearest-term application for the devices is in the retro-fitting of the FE2 laser pre-amplifier. This driver employs a topology that is scaleable to KrF IFE power generation. It is a fast Marx-charged, single-stage magnetic pulse compressor. The Marx, as delivered in 2004, is gas-switched, but specifically designed to be retro-fitted with the first generation of the program´s LGPT´s. Full scale KrF IFE-class pulsed power compressors have also been conceptualized, and will be utilized in those full-scale designs in a follow-up program to further develop the technology