Characteristics of magnetically insulated diode in a multi-shot operation

To clarify the mechanism of the production of anode plasma in magnetically insulated diode (MID), beam characteristics in a multi-shot operation were evaluated experimentally. The MID was successively operated without braking the vacuum. An ion current density (Ji) of 350 A/cm2 was observed at the first shot when diode gap was 5 mm. The value decreased with increasing the number of shot, and at 7th shot Ji was decreased to be less than 150 A/cm2. After 7 shots, the surface of anode was observed and found that it was covered with sticked matter of metallic materials such as Zn, Al, Fe, Cu, and it seems to be produced by the ablation of the electrode of MID. By eliminating the sticked matter form the surface, Ji was recovered to the initial value. From the fact, the decrease of Ji is due to that the anode is covered with the sticked matter, which prevents the growth of anode plasma. (author)