抄録
This paper describes surface charging and flashover characteristics of a cylindrical quartz spacer subjected to a ramped DC voltage in vacuum. Flashover along the side surface of a cover glass protecting photovoltaic solar batteryarray causes sever problems for the operation of a high voltage power generation system in space. We have studied the charging and flashover characteristics that depend on quartz thickness and average roughness of the side surface. The thickness is varied from 0.3 mm, which is close to that of practical cover glasses, to 10 mm, and the roughness from 0.03 µm up to 3 µm. As a result, we have found that the flashover strength for the smoothest surface shows a pronounced increase as the thickness decreases bellow 3 mm. The flashover strength also increases with the roughness in particular when it is larger than about 2 µm. The charging has been observed by using a capacitive probe embedded into the cathode and the results are analyzed by a simulation based on the Secondary Electron Emission Avalanche mechanism. The observed and simulated results very well agree with each other for the variety of thicknesses examined. The accumulated charge decreases with the roughness and, at a certain level of the applied voltage, the surface no more acquires charge for an average roughness larger than about 2 µm. These results explain the reason why the flashover strength increases with the roughness. These results are useful for designing a cover glass of the solar power generation system.
