Surface Morphology Evolution of W-Ni-Fe Alloy Electrode Under Repetitive Pulsed Discharges

The conduction of the gas switch is accompanied by spark/arc discharge. The high temperature and current density of the plasma channel will cause erosion on the surface of the electrode material. In particular, in repetitive pulsed power systems, electrode erosion has a sizeable influence on the performance of the system. Recent research has proven the superior properties of W-Ni-Fe alloy over traditional W-Cu composites in spark gaps. Not only the resistance of arc erosion, but the operating characteristics were evidently improved when W-Ni-Fe alloy was applied. This paper focus on the erosion morphology evolution of W-Ni-Fe alloy electrodes in a spark gap. In the experiment, the electrodes were tested with 100 kA level pulsed discharges for 10,000 shots (~1.3 C of transferred charge per shot). Surface profiles of 4 pairs of 90WNiFe (90 wt.% of W), 93WNiFe (93 wt.% of W), 97WNiFe (97 wt.% of W), and 90WCu (90 wt.% of W) were measured. A group of parameters has been proposed to characterize the features of surface profiles. Evolution of surface morphology features was therefore analyzed based on those parameters.