Ion charge state distribution in vacuum arc plasmas for composite Sn-Pb cathodes

The report presents experimental results on the parameters of vacuum arc plasmas produced with composite Sn-Pb cathodes differing in atomic composition. The plasma was generated on a Mevva-V.Ru ion source. The mass-charge state of the plasma was studied using a time-of-flight spectrometer. The plasma parameters were compared with those for pure Sn and Pb cathodes. It is shown that the ion fraction of each cathode component in the plasma corresponds to its atomic fraction in the cathode material. The charge state of ions of both components is determined by the average electron temperature in the cathode spot plasma. The mean ion charge state for pure cathodes is higher than that for composite Sn-Pb cathodes. The physics of the observed effects is discussed.