| 摘要 |
PURPOSE:To obtain a device having higher insulating performance by lowering the strength of an electric field of the triple junction part according to the shape of the contacting part of an insulator and a conductor. CONSTITUTION:The base of the cylindrical projecting part 20 provided on a shield electrode 2 is closely contacted with the base of the hollow part 30 (the surface of an insulator in the hollow part) while being composed in such measure as leaving a gap of an appropriate size on the part, in which the shield electrode 2 and an insulator 3 are facing, other than said closely contacted part. Thereby, there is no electric field accelerating electrons accelerated by an electric field Ea above the figure so that said electrons are puzzled near the triple junction part 10 thus generating the electric field in the opposite direction to the electric field Ea due to field-effect of said electrons so as no more to be able to generate electron avalanche while causing no creepage flush circuit. |
