Krypton Fluoride (KrF) lasers are an attractive candidate for a high energy fusion driver. Their short wavelength and demonstrated high beam uniformity optimize the laser-target physics, their laser spot size can be readily decreased to follow the imploding pellet, their modular architecture lowers development costs, and their pulsed power based industrial technology scales to a fusion power plant sized system. The two main challenges for the fusion energy application are to develop a system with an overall efficiency of greater than 6%, and durability of greater than 3 x 10~8 shots, or two years at 5 Hz. (The efficiency requirement is based on target gains of 100, which is below the gain of 150 predicted by present high gain target designs.) These issues are being addressed with the Electra (500 J, 5Hz) and Nike (3000 J, single shot) lasers at NRL. Based on recent advances in pulsed power, electron beam generation and transport, hibachi (foil support structure), and KrF physics, wall plug efficiencies of greater than 7% should be achievable. Moreover, recent experiments show that it may be possible to realize long-lived hibachi foils by periodically deflecting the laser gas. This paper is a summary of the progress in KrF laser development.
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