Detailed 266 nm Thomson scattering measurements of a laser-heated plasma

Abstract

Collective Thomson scattering at 266 nm is used to obtain spatially resolved, two-dimensional electron density, temperature, and radial drift profiles of a collisional laser plasma (critical density, nc =1×1021 cm−3). An ultraviolet diagnostic wavelength minimizes the complicating effects of inverse bremsstrahlung and refractive turning in the coronal region of interest, where electron densities approach nc/10. Laser plasmas of this type are important because they model some of the aspects of the plasmas found in high-gain laser-fusion pellets irradiated by long pulse widths (tL≳10 nsec), where laser light is absorbed mostly in the corona. The experimental results and lasnex [Comments Plasma Phys. Controlled Fusion 2, 51 (1975)] simulations agree within a percent standard deviation of 40% for electron density and 50% for electron temperature and radial drift velocity. Thus it is shown that the hydrodynamics equations with classical coefficients and the numerical approximations in lasnex are valid models of laser-heated, highly collisional plasmas.