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. (paper)