Instability phenomenon of high-frequency vacuum arc discharge associated with anode activity

Instability phenomena of high-frequency vacuum arcs with an ∼100-kHz current waveform and active anodes were observed by using high-speed photography and optical emission spectroscopy and analyzed with a conventional theoretical model. Our experimental and theoretical studies demonstrated that the instability mechanism for the transient vacuum arcs was completely different from that for the well-known quasi-stationary diffused arcs, where a cathode process predominantly contributes to the instability phenomena. In the case of the high-frequency vacuum arcs, the instability phenomena were mainly induced by a collaborative anode process operated by anode evaporation and anode voltage drop.