The Electra [1] program's LGPT [2] devices that were scaled up in area to meet the specifications for our KrF IFE pulse compressor designs have been under test and fine-tuning for the past year. The 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 cm{sup}2, for an 800 ns pulsewidth, and di/dt's of up to 25 kA/usec/cm{sup}2. We now have two practical methods 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 side-shine geometry provides a more uniform illumination over a larger silicon volume, and can have an advantage in forward losses and durability over the earlier method. It also promises to be a more economical integration than the former. Both versions of the integration are undergoing durability evaluations at this time, with plans to down-select sometime in the next year. The nearest-term application for the devices is in the retro-fitting of the FE{sup}2 laser pre-amplifier [3] that was delivered to the Naval Research Laboratory, Washington DC in early 2004. 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 it is expected that these switches will be utilized in those full-scale designs in a follow-up program to further develop the technology.
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