Two-dimensional electron density, temperature, and radial drift profiles of a laser plasma by 266 nm collective Thomson scatteringa)

Abstract

Collective Thomson scattering measurements performed at 266 nm on an underdense, long scalelength laser-produced aluminum plasma (nc∼1021 cm−3, Z∼7, Te≥50 eV, L≥100 μm) under moderate irradiance conditions (1011 W/cm2) are used to obtain temporally integrated, spatially resolved (30 μm) electron temperature, density, and radial fluid velocity contours. For an ultraviolet diagnostic wavelength, the effects of inverse bremsstrahlung heating perturbations and refractive turning are significantly reduced, allowing high density coronal conditions in the vicinity of one-tenth critical to be investigated. Detailed knowledge of these plasma conditions are fundamental prerequisites for understanding the distributed absorption process within fusion plasmas and for validation of the modeling accuracy of hydrodynamic codes. Fluid equations with classical coefficients should accurately apply to the plasma in these experiments because electron thermal transport is in the Spitzer regime, and the authors report relatively good agreement between the experimental results and two-dimensional LASNEX simulations.