Plasma Response to Arcing in Ionospheric Plasma Environment: Laboratory Experiment

Laboratory experiments are carried out to study the response of plasma to a sudden potential change induced by arcing on a solar array in low-Earth-orbit plasma environment. A solar array is biased negatively in a plasma chamber with insulator simulating coverglass or thermal paint located remotely from the arc point. When an arc occurs, electrons are ejected from the arc point to the surrounding plasma, producing a negative sheath. Shortly after the arc onset, the influx of positive charge into the circuit causes a jump of the potential, and the positive sheath is formed near the insulator surface. If the positive sheath meets the negative sheath near the arc point while the conductivity of the arc plasma is still high, a current path is formed between the arc point and the insulator surface. The current path supplies the positive charge on the insulator surface to the arc current and feeds energy to the arc plasma. Experimental results show that there is a safety distance beyond which arc plasmas cannot form the current path. (Author)