Hybrid model studies of ion dynamics and magnetic field diffusion during pinch implosions

Abstract

A one-dimensional numerical hybrid model (Vlasov ions, fluid electrons) which includes all nontrivial field components has been devised and its predictions have been compared with experimental pinch results. The effect of microscopic electron dynamics is included on the average by the specification of (anomalous) resistivity and thermal conductivity coefficients. The model has reproduced the magnetic field profiles observed during the implosion and post implosion phases of several screw pinch experiments. The behavior of the imploding plasma as various physical parameters are changed is discussed. The foot in the front of an experimentally determined density profile of a high density theta pinch is reproduced and shown to be due to a reflected ion beam. For some conditions the formation of a reflected ion beam is found to be dependent upon whether the bias is parallel or antiparallel to the driving field.