Particle simulation of laser-produced plasmas on the basis of analytic magnetohydrodynamic solutions.

摘要

Inertial confinement fusion experiments using laser beams have reported the emission of hot electrons in large quantities. This phenomenon has been one of the major hindrances to the efficient compression of a thermonuclear target. This, however, leads to the speculation of a number of non-fusion applications and an alternative fusion confinement approach. The non-fusion applications include the study of magnetic shock propagation in conductors, laser-triggered fast switches, solid state physics in the highly nonlinear optical regime, pulse-shape detectors, compact high voltage ion accelerators, LDLC (Laser Driven Liner Compression), laser-driven propulsion, direct conversion of laser energy, and astrophysical experiments. The alternative fusion concept that has recently received serious attention is the magnetically-insulated inertial confinement fusion (MICF) proposed by Hasegawa. Successful achievement of these goals however requires a thorough understanding of the problems related to the transport of hot electrons. This work is, therefore, intended to study the transport of hot electrons in the presence of the self-generated magnetic field, which is known to alter the heat transport properties drastically. For effective analysis of the hot electron transport problem, a particle simulation code is developed based on an analytic self-similar model of the laser-produced plasma that includes the self-generated magnetic field. The code is thus capable of predicting various time-dependent transport properties of a laser-produced plasma with computational speeds two orders-of-magnitude faster than existing codes. The code developed in this work can also compute the evolution of plasma parameters over a long period of time. The results of this code calculation are in excellent agreement with those of previous work. Similar analysis is used to characterize the confinement properties of MICF. It is shown that the use of an MICF scheme would allow for two orders-of-magnitude improvement in energy confinement time over the conventional ICF scheme.