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本文介绍一台用B-A型超高真空计作压强指示的标准微小漏孔的校准系统。利用超高真空四级油扩散泵系统,经烘烤420℃,保温1～2小时后,系统真空度可达(1～2)×10~(-9)托。系统采用低熔点合金的超高真空无油密封阀门,关闭阀门后,测试体积内本底漏率系1.2×10~(-12)托·升/秒或趋近于零。本系统可测定10~(-4)～10~(-11)托·升/秒(空气)或更小漏率的漏孔,通过误差分析:其漏率≥10~(-8)托·升/秒时最大误差≤17％;漏率≤10~(-9)托·升/秒时最大误差≤23％。采用超高真空系统及其B-A型真空计,不仅提高了系统测试的灵敏度,而且大大地缩短了测试微小漏孔(<10~(-8)托·升/秒)的时间。由于在B-A型真空计上配接了0～10 mV的自动记录仪,可精确地自动地绘出压强与时间的关系曲线(与理想直线一致),这样不仅可减少人为的测量误差,提高测量精度,而且大大减轻了测试人员的劳动。通过与国内外标准漏孔的初步对比测试结果表明:我们所设计的校准系统,对漏孔漏率的测定是准确的,同时也说明系统的稳定性、重复性较好。
This article presents a calibration system for standard tiny leaks using a B-A ultrahigh vacuum gauge for pressure indication. Utilizing ultra-high vacuum four-stage oil diffusion pump system, the system vacuum degree can reach (1 ~ 2) × 10 ~ (-9) Torr after baking at 420 ℃ for 1 ~ 2 hours. The system uses ultra-high vacuum oil-free sealed valve with low melting point alloy. After closing the valve, the bottom leakage rate in the test volume is 1.2 × 10 ~ (-12) Torr · L / sec or approaches zero. The system can measure 10 ~ (-4) ~ 10 ~ (-11) Torr · L / s (air) or less leak rate leakage hole, through the error analysis: the leakage rate ≥ 10 ~ (-8) L / s when the maximum error ≤ 17%; leakage rate ≤ 10 ~ (-9) Torr / l when the maximum error ≤ 23%. Using an ultrahigh vacuum system and its B-A type vacuum gauge not only increases the sensitivity of the system test, but also greatly reduces the time required to test for tiny leaks (<10 -8 Torr / second). Due to the automatic coupling of 0 ~ 10 mV on the BA type vacuum gauge, the pressure-time curve can be accurately and automatically plotted (coinciding with the ideal straight line), which can not only reduce the man-made measurement error and improve the measurement Accuracy, but also greatly reduce the testers’ labor. Through the comparison with the standard domestic and international standard leakage test, the results show that: The calibration system we designed is accurate in measuring the leakage rate of the leaky hole, and also shows the stability and repeatability of the system.