Development of high-performance KrF and Raman laser facilities for inertial confinement fusion and other applications

Abstract

This article describes the current status of the KrF development programme based on the Sprite laser system at the Rutherford Appleton Laboratory. High reliability and high shot rate have been demonstrated. Using a unique KrF-pumped Raman laser architecture, beam brightness exceeding 2×1019 Wcm-2 sterad-1 giving a focussed intensity >5 ×1017 Wcm-2 has been achieved. The development of transform-limited short-pulse oscillators is shown to be of importance in avoiding spectral broadening in air propagation of high-intensity beams. Beam smoothing of KrF beams in a multiplexed configuration has been demonstrated for the first time. The technique of echelon-free induced spatial incoherence has been shown to produce smooth intensity distributions in the far field, which remain essentially unchanged on amplification. The development of pulsed-power systems capable of exciting multikilojoule laser amplifiers for the next phase of development, the Supersprite system, is briefly discussed.