Study of directed ion velocities in a vacuum arc by an emission method

Directed ion velocities in a vacuum arc discharge plasma are measured on th e basis of a study of the ion emission current response to a rapid change o f arc current. It is shown that these velocities are about 10(6) cm/s, are determined by the cathode material, and are almost independent of the ion c harge number. Applying a magnetic field results in an increase in the direc ted ion velocity. As the gas pressure increases, the directed ion velocity decreases; this is the only case where the directed velocities are observed to depend on the ion charge number. (C) 2000 MAIK "Nauka/ Interperiodica".