B-A 真空計の感度係数変化に関する数値シミュレーション

抄録

  Sensitivity coefficient of a Bayard-Alpert gauge depends on the diameter of its envelope. In our measurement, some gauges with small envelope of diameters 35 mm and 38 mm showed higher sensitivity coefficients by 20%-40% than those with large envelope of diameters 54 mm and 70 mm for nitrogen in high vacuum of about 10⁻⁴ Pa. One gauge showed a small dependence of the coefficient on the diameter. In order to explain these results, computer simulations of the generated ion density distribution and the ion collection efficiency inside the grid were performed. Then the sensitivity coefficient was calculated using the ion density distribution and the collection efficiency. The calculated sensitivity coefficient was qualitatively in good agreement with that obtained from experiment.