Cathode Spot Splitting of Metal Deuteride Film Vacuum Arc Ion Source

A metal film containing deuterium was used as electrode of vacuum arc ion source. With the discharge arc current of 10–30 A, the behavior of cathode spots includes splitting, luminous intensity, distribution, and time evolution of the pulse discharge were studied by ICCD camera high-speed photography. The experimental results indicated that the cathode spots were mainly concentrated on the contact position of cathode and insulating material, and both of the emission region and intensity increased with the increase of the discharge arc current. Time series research showed that an initial single cathode spot first became larger and stronger, then split into multiple cathode spots, and finally extinguished during the ion source pulse duration. Both the average luminous intensity and cathode spots’ number increased with the arc current. Plasma clouds are formed in the range of 10–$100~\mu $m near cathode spots due to the release, ionization, and diffusion of deuterium, which was not observed when using pure metal as electrode. After discharge, large area of ablation on cathode surface, plasma deposition on insulation gap, and small area of ablation marks on anode surface could be observed. The whole ablation and plasma deposition area were very consistent with the observed luminescence area during discharge.