A general framework for evaluating electrode erosion under repetitive high current, high energy transient arcs

Electrode erosion is a harmful phenomenon in applications where thermal plasma appears. However, little attention has been paid to establishing a systematic evaluation methology for it. This paper proposed and verified a framework for evaluating electrode erosion under repetitive pulsed discharges. Specifically, erosion can be evaluated from the angles of operating characteristics, macro-morphology, micro-morphology, and chemical compositions. Pilot experiments on W-Ni-Fe and W-Cu electrode erosion were performed and results analysed to verify the validity of this framework. It was found that the erosion behaviours of W-Cu composites were different from those of W-Ni-Fe alloys in many aspects, such as self-breakdown voltage distribution, erosion morphology (microstructures), arc plasma channel compositions, etc. For example, W-Cu electrode surface was split by long cracks with ∼50 μm depth to 200-400 μm polygons, while W-Ni-Fe electrode surface was filled by pits and protrusions with a typical diameter of ∼20 μm. Finally, factors leading to those differences were analysed and causal relationships discussed based on the results of this framework.