Unipolar arc behavior in high-frequency fields

In the present paper, we describe experimental investigations of unipolar arcs generated in a vacuum arc plasma. An effect of additional injection of the high-frequency power is studied. A coaxial floating arc probe of special design is used for the arc characteristic measurements, and the arc tracks on the polished probe electrodes are studied. The breakdown rate of the probe in the high-frequency plasma discharge is found to have an abrupt cutoff with a frequency approaching the critical value of about 10/sup 7/ Hz. Independent measurement of electrode erosion confirms this effect. The eroded mass reaches the value of 10/sup -12/ kg/spl middot/s/sup -1/ for zero frequency and falls to the value of 10/sup -13/ kg/spl middot/s/sup -1/ for frequency approaching 10/sup 7/ Hz.