A Further Study on Surface Morphology and Erosion Products of 90WCu Alloy Electrodes

This paper studies the erosion of a pair of copper-tungsten alloy (90% mass percent of tungsten) electrodes in a two-electrode spark-gap switch. In the experiment, the switch was operated without cleaning for 20 000 shots (17 160 C transfer charge) at ~0.1 Hz repetition rate. Experimental results indicate that with the increase in number of shots, the cathode presents a severer erosion and there also appears a more serious erosion at the electrode's outer zone than at the central zone. Moreover, erosion features such as protrusions, craters, and cracks at different locations of the surface are quantitatively analyzed and compared. As for erosion products, X-ray photoelectron spectrometer is adopted to analyze the constitutions of the electrode surface. The results reveal an interesting phenomenon regarding the distribution of Cu atom. Initially, the percentage of Cu atom is 24.33%. After 20 000 shots, on the anode surface, the percentages of Cu atom become 13.38%, 26.32%, and 18.75% at the central position, the middle position, and the edge position, respectively. Nevertheless, on the cathode surface, the percentages change to 26.32%, 36.42%, and 39.70%. These results quantitively describe the variations of the electrode during the aging process of a switch, which might be meaningful for electrode erosion research and related applications.