Study on the microspot splitting characteristics of pulsed cathodic vacuum arc

Abstract

The intense pulsed current superimposed on direct current arc discharges can promote arc spot splitting and reduce macroparticle ejection. In this study, the effects of different arc parameters including peak current, magnetic fields, pulse frequency and duty cycle on spot splitting characteristics for the pulsed cathodic arc discharge, as well as mechanisms involved in microspot formation, are investigated. The results show that under the effect of periodic micro-explosive emissions, the micro-spot splitting at the peak of the pulse displays a multi-stage annular expansion phenomenon, and its expansion radius increases with the increaseing peak current; the increasing transverse component of the arc source magnetic field gradually changes the microspot splitting pattern from annular expansion to arc-shaped expansion; the plasma motion after the micro-explosion requires a period of time to “accumulate force.” In addition, an increase in pulse frequency leads to a gradual reduction in the range of the microspot splitting, in which the microspots are in a relative aggregation state; an increase in duty cycle, leads to an instability in the continuous motion of the microspots after the splitting in the peak period. This causes some of the microspots to merge, exhibiting a trend similar to the direct current arc.