Numerical modeling of suprathermal electron transport in laser-produced plasmas. Report number 36

Supra-thermal electrons can radically alter the dynamics of imploding laser fusion targets by preheating the target material, by transforming energy to a rapid ion blowoff or, due to mean free path effects, decoupling the core from the corona. In order to correctly simulate the dynamics of a laser driven target, it is necessary to develop an accurate physical and computational model of these electrons. The difficulties inherent in this problem can be appreciated by noting that the supra-thermal velocities can vary by over an order of magnitude while the density of the background thermal electron fluid through which they propagate can vary by over four orders of magnitude. Since the supra-thermal mean free-path is proportional to v{sup 4}/n{sub e}, there can be an eight order of magnitude variation in this scaling parameter. Since the transport of supra-thermal electrons must be followed in both the diffusive and free streaming limits, neither flux limited diffusion models nor truncated moment methods are adequate. A three component model of transport of supra-thermal electrons is developed here to satisfy all requirements discussed in this paper