Transition in velocity and grouping of arc spot on different nanostructured tungsten electrodes

Abstract

Behavior of arc spots was investigated in detail using a nanostructured tungsten specimen with different thicknesses of the nanostructured layer. From the observation using a fast framing camera, it was found that the velocity of the arc spots significantly altered as passing the boundary of the two layers. The changes in spot velocity and spot width were discussed theoretically using the ecton model. The fractal dimension of the arc trail evaluated by using a box-counting method was significantly changed. Also, the width of arc trail was increased with the nanostructured layer thickness. From the SEM analysis of the specimen, the amount of tungsten eroded by arcing for two different thickness cases was estimated, and the erosion rates were discussed. © 2014 The Authors.