Electron Transport Modeling in Inertial Confinement Fusion Experiments

Thermal transport plays an important role in inertial confinement fusion. The Spitzer--Harm model has conventionally been used in hydrocodes. Such a model, however, breaks when the electron mean free path exceeds a few percent of the spatial scale length in a plasma. To extend the validity of the model, a flux limiter $f $is introduced and the Spitzer flux $q_{SH}$ is replaced by a fraction of the free-stream flux \textit{fq}$_{FS}$ in regions where $q_{SH} \quad >$ \textit{fq}$_{FS}$. Alternatively, a convolution form\footnote{ J. F. Luciani \textit{et al}., Phys. Rev. Lett. \textbf{51}, 1664 (1983); E. M. Epperlein and R. W. Short, Phys. Fluids B \textbf{3}, 3092 (1991).} and multigroup diffusion model\footnote{ G. P. Schurtz \textit{et al}., Phys. Plasmas \textbf{9}, 4238 (2000).} of the thermal flux have been proposed in the past. In this talk, a new nonlocal model is presented which takes into account the finite deposition range of electrons. Such a model is based on the solution of a simplified kinetic equation. Heat flux, calculated with the model, is used in the hydrocode \textit{LILAC} to simulate ICF experiments. Comparison of the results of such simulations with both the experimental data and Fokker--Planck simulations will be presented. This work was supported by the U.S. Department of Energy Office of Inertial Confinement Fusion under Cooperative Agreement No. DE-FC52-92SF19460.