スペーサを持つ平板電極系によるヘリウムガスの絶縁破壊特性

抄録

The condition of saturated superfluid helium produces easily the discharge environment near the Paschen minimum condition of gaseous helium. It is very important from a point of magnet protection to know surface breakdown voltage in that condition. We measured breakdown voltage of surface or gap discharge in gaseous helium the condition of which is some higher regime than saturation temperature for various pressures (1.33 to 101kPa), using parallel plane electrodes with a tested spacer. In the tested regime, the breakdown voltage obeys Paschen's law and changes only with the density-thickness product. In lower density-thickness product range, surface discharge can hardly occur before the gap dischage develops, and breakdown voltage is the same as that of the same spacing gap dischage without the spacer. In higher density-thickness product range, surface breakdown voltage is lower than the gap breakdown voltage. Within the scatter of the data, breakdown voltage is independent of spacer diameter and thickness.