DEVELOPMENT OF HIGH-PERFORMANCE KRF AND RAMAN LASER FACILITIES FOR INERTIAL CONFINEMENT FUSION AND OTHER APPLICATIONS

This article describes the current status of the KrF development progr amme based on the Sprite laser system at the Rutherford Appleton Labor atory. High reliability and high shot rate have been demonstrated. Usi ng a unique KrF-pumped Raman laser architecture, beam brightness excee ding 2 X 10(19) W cm-2 sterad-1 giving a focussed intensity >5 x 10(17 ) W cm-2 has been achieved. The development of transform-limited short -pulse oscillators is shown to be of importance in avoiding spectral b roadening in air propagation of high-intensity beams. Beam smoothing o f KrF beams in a multiplexed configuration has been demonstrated for t he first time. The technique of echelon-free induced spatial incoheren ce has been shown to produce smooth intensity distributions in the far field, which remain essentially unchanged on amplification. The devel opment of pulsed-power systems capable of exciting multikilojoule lase r amplifiers for the next phase of development, the Supersprite system , is briefly discussed.