A time-correlated study of the Z-pinch discharge in helium

Abstract

The development of a miniature "gradient probe" and the successful superposition of multiple photographic recordings have produced useful insight into the action of the Z-pinch discharge in helium.A correlation of luminosity and current fronts yields strong evidence for the occurrence of a nonionizing shock wave at high initial pressures in helium discharges. The relatively nonluminous shock front is followed by overlapping regions of He I and He II radiation within the collapsing current shell. At low filling pressures these two regions coincide and radiation is emitted from almost all the gas trapped within the current shell. In all cases the zone of maximum He II emission is observed to coincide with the position of maximum current density.Synchronization of the discharge current with time-resolved spectroscopic results indicates the presence of successive pinches. They are caused by the interaction of thermal and magnetic pressures after the first collapse of the discharge.