Implosion of heavy metal liners driven by megaampere current pulses

Abstract

This paper describes a theoretical and experimental study of the implosion of heavy copper liners shaped as hollow cylindrical tubes having an outer diameter of 3 and 4 mm and a wall thickness of 500 μm; the tube linear mass was 0.35 and 0.5 g/cm, respectively. The experiment was carried out on the GIT-12 pulsed-power generator (5 MA, 2 μs). Under these experimental conditions, a skin effect occurred in an imploding tube. The implosion process was numerically simulated based on a radiative magnetohydrodynamic model. Both the experiment and the simulation have shown a fluctuating voltage across the tube. According to the simulation, the first fluctuation peak, followed by a sharp decrease in voltage, is associated with the “collapse” of the tube on the axis and the formation of a strong shock wave. The times at which first voltage peaks were detected in the experiment and the first peak occurrence times obtained in the simulation coincided to within 5–10%, and the experimentally obtained and the calculated voltage amplitudes differed by about 20–30%. Thus, the results of the experiment suggest that using oscilloscopic measurements of the voltage across a heavy metal tube, it is possible to detect the shock wave generated in the conductive material of the tube and to determine the collapse time.