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研究出一种噪声电流调制系数小,可测极高真空的三栅 BA 规。图1示出这种规的手动调制结果。通一断时收极集上的电流差ΔⅠ在6×10~(-11)托以上范围内与压力成线性关系,目前还在设法扩展低于该压力的线性关系。但是由于ΔⅠ值太小,受到直流检流计的响应时间的限制,需要很长的测量时间。为此,通一断改为自动切换,收集极电流检出的是交流信号,从而有可能测量更低的压强。这就是自动调制。三栅调制 BA 规的电极结构:三个圆筒状栅极以离子收集极为中心同心配置(从外层起按G_1,G_2,G_3 顺序排列)。灯丝电位400伏,G_1 为500伏,收集极为地电位,G_2 为从50伏到350伏范围变化的正弦波电压。G_3 则应在300伏左右稍许变化。为了使G_3 周围保
A tri-gate BA gauge with small current modulation coefficient and high ultimate vacuum was developed. Figure 1 shows the result of this manual modulation. The current difference ΔI on the collector-collector set is linearly proportional to the pressure within the range of 6 × 10 ~ (-11) Torr. The linear relationship below this pressure is still being explored. However, due to the ΔI value is too small, subject to the DC galvanometer response time constraints, requires a long measurement time. To this end, through a switch to automatic switching, the collector current is detected by the exchange of signals, it is possible to measure lower pressure. This is automatic modulation. Triangular Modulation Electrode Structure of BA Gauge: Three cylindrical grids are arranged concentrically with respect to the ion collector (in order from the outer layer, G_1, G_2, G_3). The filament potential is 400 volts, G_1 is 500 volts, the collection is at ground potential, and G_2 is a sinusoidal voltage that varies from 50 volts to 350 volts. G_3 should be slightly changed in the 300 V or so. In order to make G_3 around Paul