Experimental Studies of Sheath Formation in Electronegative Plasma in a DC-discharge device (EPaX) at the University of San Diego (USD)

Despite the outstanding success of plasma processing applications using electronegative plasma over the last several decades, there remain open questions regarding the physics of sheath formation in such systems. While the model of Braithewaite and Allen (1988) is generally assumed to be the case, direct experimental benchmark experiments are still lacking. Further, a focused set of benchmarking experiments directly measuring potential profiles in the neighborhood of sheaths near conducting boundaries, for a variety of electronegativities, is also still lacking. A DC-discharge device at the University of San Diego (USD), a principally undergraduate institution, is nearing completion designed for discharges using corrosive gas feed stocks such as molecular iodine and oxygen. The plan is to commission the device in Argon, then Argon-Oxygen, and then Argon-Iodine discharges. The first discharges are now planned for Summer of 2021. Progress and results will be presented.