Experiment and simulation of generation of highly charged ions in a pulsed vacuum arc

Abstract

A comparison is made of experimental results on the generation of multiply-charged bismuth ions in a vacuum arc plasma with a current pulse of half maximum width 2.5 μs and maximum amplitude 3 kA, and numerical simulation of the generation of multiply-charged bismuth ions in this plasma. Images of the luminous arc plasma were obtained experimentally with nanosecond exposure times at different times throughout the arc current pulse, and simultaneously the ion mass-to-charge composition of the plasma was measured at these times. It is shown that the generation of bismuth ions with charge states of 10+ and higher is associated with compression of the plasma column by its own azimuthal magnetic field, which occurs when the arc pulse current reaches its maximum value. Based on a hybrid hydrodynamic model, the spatial distributions of the arc plasma density, electron temperature, and charge state composition of plasma ions were calculated, which makes it possible to obtain a calculated image of the plasma glow. A comparison of the experimental ion charge-state distributions and photographs of the plasma glow with data obtained from the calculation shows good agreement, which theoretically confirms the generation of high charge state ions during pinching of the arc column.