Statistical analysis of particulate concentration from electrode erosion of gas discharge

In discharge processes, electrode erosion is inevitable and may be a primary cause of gap failure. Features generated from electrode erosion, such as particulates and pits, would lead to field distortion and self-breakdown failure, in essence. To quantitatively clarify how these features of erosion are generated as the discharge shot accumulates, this paper introduces a statistical method to analyze particulate concentration in the eroded surface. Based on experimental data from laser confocal microscopy, this method could extract and process the profile of the electrode surface after different discharge shots. Statistical results indicate that conditioning effects have been found in the first 100 shots, where the discharge arc plays a role to polish more prominently, rather than ablate, the electrode surface. After this period, electrode erosion could be found to be increasingly heavier and the number of particulates and pits increases rapidly. The proportion function of the particulates height or pits depth can be fitted by power distribution and the correlations between the two function coefficients a, b and discharge shots number n are roughly linear, positive and negative, respectively.