Atmospheric pressure operation of a KrF laser oscillator and/amplifier with a krypton-rich mixture and a Kr/F/sub 2/ mixture

Atmospheric pressure operation of the electron beam (e-beam)-excited KrF laser can greatly reduce the design constraints on a large-aperture laser module in the megajoule-class system as an inertial confinement fusion driver. The krypton-rich and Kr/F/sub 2/ mixtures are suitable for the atmospheric pressure operation because these can produce high specific output energy without serious reduction of the intrinsic efficiency compared with conventional argon-rich mixtures. A 50-ns e-beam generator was used to pump the KrF laser oscillator with which fundamental studies of the KrF laser with atmospheric pressure krypton-rich mixtures were performed. A larger apparatus, using another 65-ns e-beam generator, demonstrated a specific output energy of 6.6. J/iota from a Kr/F/sub 2/ mixture with an intrinsic efficiency of 6%. The latter apparatus was then used as an oscillator-amplifier system to investigate the amplifier characteristics of the KrF laser because the atmospheric pressure krypton-rich mixture is useful for large amplifier modules