Amplifier pumping optimization (in French)

Slabs in NIF/LMJ large-aperture amplifiers are set at Brewster angle between two lamp arrays. A 2D+ ray-trace code is used to predict pump and gain coefficients profiles in the aperture. Code predictions, in good agreement with experimental results, show the high decay rate due to amplification of spontaneous emission leads to a strong depletion of the stored energy on the edges of the slabs. To compensate for this roll-off, shaped reflectors were calculated at CEL-V, using a dedicated routine added to the ray-trace code. They were fabricated and tested on the modified beamlet amplifier at LLNL. Numerical and experimental results agree to show that it is possible to redirect light using shaped reflectors, and that directing the pump radiation towards the edges of the aperture leads to a more uniform gain.© (1997) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.