Simulations of Explosive Electron Emission in Cathodic Arcs

Explosive Electron Emission (EEE) is typical to cathodic arcs. The physics of multi-phase phenomena associated with self-sustained formation of explosive emission centers (ectons) is not fully understood. This SBIR project will conduct experimental, theoretical, and computational studies of phase transitions at electrode surfaces, formation of plasma jets, and gas dynamics in cathodic sparks and arcs over a wide range of gas pressures. Experimental studies will be conducted at LBNL to understand effects of gas pressure on ecton formation and dynamics. CFDRC will apply its recently developed adaptive kinetic-fluid simulation tool for computational studies of EEE processes. This project will investigate effects of gas pressure on near-electrode phenomena and phase transitions between gas, liquid, and solid states during gas breakdown and formation of spark and arc discharges. After completing Phase II, a new multi-physics computational tool with advanced capabilities for simulations of arc discharges will be available for fundamental studies and industrial engineering of plasma systems. COMMERCIAL APPLICATIONS AND OTHER BENEFITS: In spite of 50 years history, ecton physics remains mostly empirical and focused on vacuum discharges. The project will offer better understanding of gas pressure effects on near-electrode phenomena in gas discharges. The developed computational tool will offer breakthrough capabilities for analyzing plasma surface interactions and electrode phenomena in cathodic arcs over a wide range of gas pressures. The developed tool will be used to understand unipolar arcing at first wall of fusion devices under plasma load, the formation of microcraters, the retrograde motion of cathode spots, and other phenomena typical to vacuum arcs. The project will clarify effects of gas pressure on ecton formation in sparks and arcs. The developed computational tool will be used by scientists and engineers for studies of arcing on plasma-facing components at the wall of a fusion reactor, as well as pulsed-power, e-beams, X-rays and other applications utilizing cathodic arcs. We anticipate the launch of a spin-out company to commercialize the new software tool after building critical user’s base. Key Words: Explosive Electron Emission, Ecton, Cathodic Sparks and Arcs, Adaptive Kinetic-Fluid Solvers, Multi-Phase Phenomena, Cathode Craters