Abstract
This paper describes vacuum electrical breakdown characteristics for electrodes with spark conditioning process. Two pairs of electrodes processed by spark conditioning were prepared. The conditioning procedure was 500 times repetitive breakdowns by applying positive impulse voltage under ultra-high vacuum condition. Using these processed electrodes, two vacuum gaps were made up by pairing of electrodes used as cathode in spark conditioning process and as anode, respectively. 50 times repetitive breakdown tests were carried out using cathode vs. cathode pair and anode vs. anode pair. As a result, for a pair of cathode vs. cathode, the first breakdown field kept high breakdown field which was almost the same value for the achieved breakdown field by 500 times repetitive spark conditioning. On the other hand, for anode vs. anode pair the first field was much less than that for cathode vs. cathode pair. This is due to the difference of the surface condition between anode and cathode surfaces that were formed by spark conditioning. According to SEM images for anode and cathode after spark conditioning, the profiles had quit difference between anode and cathode surface.
