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为了解决漏率小于10-12Pa·m3/s漏孔的校准问题,提出累积法与固定流导法相结合的方法,研制出下限可达10-14Pa·m3/s量级的校准装置。装置主要由累积比较系统和固定流导法流量计组成,采用四极质谱计作为比较器测量示漏He气离子流大小,通过累积的方法解决了质谱分析室中示漏气体分压力测量问题;采用激光打孔和多次镀膜的方式获得10-10m3/s量级的分子流导,用吸气剂泵将真空室本底压力维持在10-7Pa量级,使磁悬浮转子真空计对固定流导元件入口He气压力测量下限可达10-4Pa,从而获得下限为1.3×10-14Pa·m3/s的标准气体流量。研究结果表明,装置采用He气作为示漏气体的校准范围为10-12~1.3×10-14Pa·m3/s,合成标准不确定度为5.2%~5.8%。
In order to solve the calibration problem of the leakage hole with the leakage rate less than 10-12 Pa · m 3 / s, a method combining the cumulant method with the fixed flow method is proposed and a calibration device with the lower limit of 10-14 Pa · m 3 / s is developed. The device mainly consists of an accumulative comparison system and a fixed-flow-guided flowmeter. The quadrupole mass spectrometer is used as a comparator to measure the magnitude of the leaked He-ion flow. The problem of partial pressure measurement of the leak gas in the mass spectrometry chamber ; Using laser drilling and multiple coating method to obtain molecular flow conductivity of the order of 10-10m3 / s, with a getter pump to maintain the vacuum chamber floor pressure in the order of 10-7Pa, the magnetic suspension rotor vacuum gauge fixed The lower limit of the gas pressure measurement at the inlet of the flow guiding element is up to 10-4 Pa, so that the standard gas flow with the lower limit of 1.3 × 10-14 Pa · m3 / s can be obtained. The results show that the calibration range of He gas is 10-12 ~ 1.3 × 10-14Pa · m3 / s, and the standard uncertainty of synthesis is 5.2% -5.8%.