Requirement of uniformity for fuel ignition and uniformity in high neutron yield implosion

Abstract

An ignition condition for a compressed DT sphere is studied by the use of balance relation between a heating term (alpha-particle heating) and cooling terms (expansion, radiation, and electron heat conduction). The resultant condition was compared with the model simulation carried out by Fraley et al. (1974). Effect of implosion uniformity is one of the most important elements in evaluating the laser energy required for fuel ignition. Increase of the laser energy as a function of implosion nonuniformity is shown. For a self-consistent study of implosion dynamics, a two-dimensional fluid code is developed and used for analyzing the recent high neutron yield experiment (Takabe et al. 1988). Two-dimensional fluid dynamics driven by laser irradiation nonuniformity is studied to explain the difference between the experimental result and the result of 1-D fluid simulation.