A Novel Single Cathode Plasma Column Design for Process Stability and Long Component Life

Arc instability in dc plasma guns has a detrimental effect on coating quality and electrode life. This paper investigates the impact of a single-cathode plasma column design on process stability, versatility, and component life. The design increases arc length and minimizes restrike, enabling high voltage, low current operation as well as the use of ternary gas to increase enthalpy. Arc behavior is assessed by monitoring fluctuations in electrical signals and correlated with particle temperature and velocity. The takeover-steady mode is shown to be the typical operating mode of the plasma jet for this design, resulting in steady particle characteristics over long periods of maintenance-free operation.