Effect of Wire Diameter and Addition of an Axial Magnetic Field on the Dynamics of Radial Wire Array $Z$-Pinches

The operation of radial wire array Z-pinches driven by a 1-MA 250-ns current pulse was studied. Variation in the cathode diameter and wire diameter does not affect the overall plasma dynamics but controls the time of wire breakage and the time of pinch formation. The measured times of full wire ablation at the cathode were used to determine the ablation velocity (V _abl), and the results give a scaling V _abl ~ (wire diameter)^-0.46. Experiments with added axial magnetic field show an increase in the pinched plasma diameter, possibly due to the compression of the axial magnetic flux by the imploding plasma.

I. Introduction

Radial wire arrays provide an alternative approach to the study of plasma dynamics in -pinches. The processes of wire ablation and plasma implosion occur in a similar fashion in comparison with cylindrical wire arrays, although the geometry of a radial wire array allows for an easier diagnostic access to probe the conditions of the plasma. Radial wire arrays have been shown to be useful for other applications, including the formation of plasma jets that are relevant to the laboratory modeling of astrophysical outflows through laboratory experiments [1], [2].