Generation of Boron-Rich Plasma by a Pulsed Vacuum Arc With Lanthanum Hexaboride Cathode

We report on the generation of boron-rich plasma by a pulsed vacuum arc with lanthanum hexaboride cathode. Two different ranges of arc current pulse duration and amplitude were investigated: the first one has pulse duration of 5-20 μs and arc current of 100-700 A and the second one has pulse duration of 300 μs and arc current of 140 A. The ion mass-to-charge spectrum of the plasma was investigated by both time-of-flight spectrometry and magnetic analysis. The results of measurements of the plasma ion composition for different arc parameters are presented and discussed. For all arc parameters considered, the fractional composition of boron and lanthanum ions agrees well with the stoichiometric composition of these elements into the lanthanum hexaboride cathode.