Numerical studies of a field-reversed theta-pinch plasma

Abstract

A two-dimensional magnetohydrodynamic computer code has been used to model the formation of a field-reversed theta-pinch plasma. The simulations have been performed in the parameter range of the recent FRX-B experiments. It is found that an anomalous resistivity is required to explain the observed decay of reversed magnetic flux. The reconnection process is found to be sensitive to the density and amount of trapped reverse bias flux but insensitive to the assumed magnitude of anomalous resistivity. The reconnection process is more rapid and the axial plasma motion induced by reconnection is more pronounced for larger bias flux. If a straight coil is used instead of the usual shaped coil (end mirrors), full reconnection does not occur for low initial bias fields. These results are in general agreement with FRX-B observations.