Nature of high-energy ions in the cathode plasma jet of a vacuum arc with high rate of current rise

摘要

The production mechanism of extremely high-energy (up to 10 keV) ions observed in vacuum arcs having only a few tens of volts of arc voltage was considered. A model was developed for the plasma acceleration in a high-current (greater than or equal to1 kA) short pulsed (<1 mus) vacuum arc, taking into account the high rate of rise of the spot current (dI/dt>100 MA/s). A system of equations, including equations for the cathode spot and the plasma jet, was solved self-consistently with dI/dt in the range of 0.1-10 GA/s. It was shown that the plasma could be accelerated to the measured energy in the near spot region due to a gas dynamic mechanism and that the ion energy depends on the ratio of the ion flux to the electron flux. This ratio is determined by the cathode erosion rate. The calculated cathode erosion rate varies from 200 to 10 mug/C when the ion energy increases from 0.1 to 10 keV and well agrees with measurements. (C) 2004 American Institute of Physics.