Formation studies of field-reversed configurations in a slow field-reversed theta pinch

Abstract

Field-reversed configurations (FRC’s) have been successfully formed in a field-reversed theta pinch in a regime where there was little or no radial shock heating. It has been observed that even with the elimination of radial shock heating there remains sufficient resistive and compressional heating to burn through any radiation barriers caused by the low Z contaminates introduced during formation. The equilibrium behavior of the FRC was not influenced by the loss of radial shock heating other than yielding a lower equilibrium flux for a given initial reverse flux. With the slower reversal of the axial field, it was possible to exert considerable control over the formation dynamics through the use of end control coils. Two modes of formation have been identified wherein either the equilibrium flux was maximized (slingshot mode), or, plasma heating was maximized and formation dynamics were minimized (bubble mode).