Breakdown characteristics of CuCr electrode after electron beam irradiation in vacuum

For development of high-voltage equipment such as vacuum circuit breakers, it is very important to improve their dielectric breakdown characteristics in a vacuum. It is thus necessary to clarify the breakdown mechanism in a vacuum. It is well-known that these characteristics are influenced by the electrode material and its surface condition^[1][2], but the breakdown mechanism has not been clarified. This paper presents measurements of breakdown characteristics and observations of a cross-section after electron beam irradiation. The results are compared with those for no electron beam irradiation. It is thus shown that the breakdown voltage of a CuCr electrode after electron beam irradiation is higher than that for no electron beam irradiation. This is because a fine Cr layer is formed on the electrode surface.