Thermal conductivity of laser-produced plasma corona

Various methods of theoretically describing the thermal conductivity of a of plasma corona are considered. The processes of laser heating and ablating a spherical-shell target in the TRITON program (Inst. of Appl. Mech., USSR Acad. Sci.) are computer-simulated. Numerical and analytic methods are used to investigate the influence of heat-transport suppression on the principal hydrodynamic characteristics of the plasma. It is shown that the most sensitive to a reduction of the heat transport is the electron-density distribution in space and in time. The requirements imposed on experimental measurements capable of determining, in comparison with numerical computations, the degree of heat-transport suppression, are analyzed for a large range of flux densities. It is shown that when the flux density is decreased to 10¹³ W/cm² the present accuracy of measuring the position of the criticaldensity region in the corona, as well as the rate of evaporation of the material, becomes inadequate to determinethe deviation of the thermal conductivity from the classical value. Reliable conclusions concerning the transport coefficients can be drawn in this case from a comparison of high-speed interferometry data on the dynamics of a low-density corona (/_cr = 10^-3–10^-1) with the results of computer simulation.Division of Quantum Physics, Lebedev Physics Institute, Academy of Sciences of the USSR. Translated from Preprint No. 188 of the Lebedev Physics Institute, Academy of Sciences of the USSR, Moscow (1988).