On Charged Particle Flux Parameters at Vacuum Arc Current Instability and Chopping

The charged particle fluxes at vacuum arc current instabilities were investigated with three experimental methods with nanosecond temporal resolution. Total ion current, ion flux with several E/z and M/z ratios and “hot” (energy over 20eV) electrons current were analysed. The measurements reveal that current instabilities and attempts of discharge to chopping are followed by appearance of intensive ion and “hot” electron bunches. The ion flux bunches are consisted of mainly single charged ions. These bunches are appear just before arc current instabilities development. “Hot” electrons appear at negative slopes of current waveform. The assumption was made that vacuum arc instability and discharge chopping can be caused by cathode spot cell life cycles synchronization.