Ion acceleration in vacuum arc cathode plasma jets with large rates of current rise

A model of plasma acceleration in a high-current short pulse vacuum arc was developed. The mathematical description includes equations for the cathode spot and the plasma jet, which were solved for rates of current rise dI/dt in the range of 0.01-10 GA/s. The multicharged ions in the cathode spot were taken in account. It was shown that the plasma could be accelerated to the measured energy by a gasdynamic mechanism. The ion energy, cathode erosion rate, and the ratio of the ion flux to the electron flux are linked by the equations. The calculated cathode erosion rate varies from 200 to 10 μg/C when the ion energy increases from 0.1 to 10 keV. The ion current to the cathode mainly consists of singly- and doubly-charged ions. The singly-charged ion current fraction decreases with spot current decreasing and rate of current rise increasing.