Multi-Electrode Plasma Torches: Motivation for Development and Current State-of-the-Art

Multi-electrode plasma torches are becoming increasingly popular in the thermal spray community due to their good stability and high power plasma jet even when operated with inert gases. Currently the models in use feature either three cathodes and a single anode or three individual anodes connecting to a single cathode. The motivation for development of these plasma torches is based on the inherent instability of single anode/single cathode systems which leads to fluctuating plasma jets resulting in inhomogeneous particle heating. The use of multi-electrode systems has expanded into the realm of low pressure plasma spraying and vacuum plasma spraying with promising results, while atmospheric plasma spraying results show improved coating quality compared to conventional systems. Current research focuses on the development of numerical process modeling as well as the application of advanced diagnostics for process analysis, opening up opportunities for improvement and process control.