ϑ-pinch ionization for field-reversed configuration formation

The behavior of a plasma produced by a ringing ϑ-pinch discharge in the presence of a 2.3-kG bias field is examined for the case where the net field passes through zero. Experimental studies, employing internal and external field probes, indicated ∼50% of the initially applied bias flux is excluded by the plasma with this ionization technique. A theoretical model incorporating field diffusion and elastic ion-neutral collisions is used to describe the observed dynamics of the plasma sheath.