Investigation of the mass-charge composition of cathode material ions in the low-current vacuum arc plasma

Charge-state distribution of cathode material ions in the vacuum arc plasma was investigated via the Thomson spectrometer with automated recording and processing of spectrograms. Arc discharge current was varied in range 1.7-110 A. There was obtained the dependence of the mass-charge composition of the ions on the current pulse amplitude. Average charge number for copper ions decreased with arc current decreasing from 2 at the 100-150 A value of current amplitude to 1.55 at the 1.7 A value. Generally, mean charge was affected by increasing of the Cu+ fraction and decreasing of the fractions of higher charge-state ions with decreasing of the current pulse amplitude.