Experimental study on arcing initiation mechanism based on electric current and optical emission measurement in a capacitively coupled plasma

Arcing has attracted great interest in both industrial and academic fields for over 120 years, as it induces severe damage to the material surface regardless of the materials involved and originates from multi-dimensional scale dynamics. However, its mechanism, especially under a moderate-density (10⁰⁹–10¹¹ cm^-3) plasma environment, has yet to be fully understood. This presentation provides an experimental study on the initiation mechanism generated on an arcing-inducing probe under a radio-frequency capacitively coupled plasma environment. We employed multi-diagnostic methods, including voltage/current probes, an ultra-high-speed camera, and an optical emission spectrometer. We found that the light emission from the arcing spot corresponds to the arcing current induced by thermofield electron emission. Furthermore, metal evaporators were observed in the optical emission spectra, indicating a high temperature on the arcing spot sufficient for vaporization. Based on these findings, we reveal that ionization collisions between emitted electrons and evaporated atoms initiate an electron avalanche near the emission spot, leading to the initiation of arcing.