速報
三極管型電離真空計の比感度係数に及ぼす空間電荷の影響
2017 年 60 巻 12 号 p. 490-494
詳細
2017 年 60 巻 12 号 p. 490-494
Secondary standard ionization gauges (VS-1) had been calibrated by using the primary standard McLeod gauge at former Electrotechnical Laboratory for about twenty years around 1980's. VS-1 is a triode gauge. Sensitivity coefficient of VS-1 was measured experimentally and reported by Hirata et. al. Simulation of the electrical potential profile of the gauge, electron trajectory emitted from a hot filament, and ion current produced by electron impact ionization of gas assuming a simple electrode geometry was done. The space charge is also taken into consideration in the simulation. In the simulation results in the pressure range above 10−2 Pa the relative sensitivity coefficient of Ar increased with pressure and that of He decreased with pressure. In the pressure range between 10−3 Pa and 10−2 Pa the relative sensitivity coefficient of Ar and He were constant respectively. These features are similar to the experimental results. Taking the characteristics of the relative sensitivity coefficient into account, it is recommendable to use this gauge in the pressure range between 10−3 Pa and 10−2 Pa.
