Large-Scale Stimulated Rotational Raman Scattering Experiments Using the LLNL (Lawrence Livermore National Laboratory) Nova Laser

摘要

The LLNL Nova laser is a ten-beam neodymium-glass laser system which can generate up to 15 kJ per beam in a few nanoseconds. Stimulated rotational Raman scattering (SRRS) in air limits the power delivered to one of the two target chambers of the laser if the beams are allowed to propagate in air over the entire distance. We have therefore conducted experiments using Nova to study the growth and properties of SRRS in air to assess its importance for Nova, future fusion lasers. Our early experimental results were published last November (Opt. Lett., 10, 565 (1985)). These show that the growth of SRRS from amplified spontaneous emission (ASE) in a high Fresnel number geometry is in agreement with predictions from calculated gains, and that the near-field distribution of the Raman-shifted radiation is a divergent beam with a fine speckle structure. (ERA citation 12:043759)