ARGUS Laser Plasma Experiments at 1.06 mu M, 0.53 mu M and 0.35 mu M

摘要

ARGUS wavelength scaling experiments have been performed on low (Be) and high (Au) Z disk targets, with laser wavelengths of 1.06 mu m, 0.53 mu m and 0.35 mu m. The laser provided a 700 psec pulse, with up to 100J and 1.06 mu m; 200J at 0.53 mu m; and 40J at 0.35 mu m. Laser intensities on target ranged from 3 x 10 exp 13 to over 3 x 10 exp 15 W/cm exp 2 , using an f/2.2 focusing system. Box calorimeter measurements show the expected increasing fractional absorption at shorter laser wavelengths; absolutely calibrated hard x-ray detectors show the number of suprathermal electrons to be greatly decreased. Scattered light measurements concentrated on stimulated Raman scattering, and the 3/2 harmonic. The SRS was spectrally and temporally resolved during 0.53 mu m irradiations; our measurements showed the scattering to be principally from the convective instability, near tenth critical density. Near omega /2, a double peaked spectral feature is observed. The time resolved data show a number of interesting features, which are discussed.