研究目的

The study of vacuum breakdown is very important for the design of high voltage vacuum electron devices, such as vacuum interrupters, particle accelerators, linear microwave tubes and pulse power generators. Explosive electron emission (EEE) is generally believed to play a fundamental role in the initiation of vacuum breakdown. This paper evaluates the field enhancement effects of microstructures of electrode surfaces with two different polishing treatments based on microscopic observations and analyzes the influence of the field enhancement effects on the EEE. Moreover, the EEE sites on cathode surfaces are studied by micro-examination, energy spectrum analysis and metallographic analysis.

研究成果

The field enhancement effect does have an influence on the breakdown strength of the vacuum gaps. However, the cathode EEE cannot be induced just by the electrical field enhancement effect of the cathode surface irregularities. The grain boundaries on the cathode surface have an important effect on the EEE and the vacuum breakdown, especially for the polished cleaned cathodes. The lower work function and the lower melting temperature at the grain boundaries should be important factors of the EEE at grain boundaries.

研究不足

The study acknowledges that the EEE is an intricate phenomenon and there may be additional factors in the initiating process not covered in this study. The exact conclusion on the initiation of EEE has not been reached.