固定流导法校准真空漏孔方法研究

固定流导法采用的是分压力测量技术,对质谱分析室的漏放气率的指标要求不高.通过实验得到四极质谱计的非线性引起的测量误差可达38%,在具体校准过程中能够很好调节稳压室中的气体压力,使通过小孔的气体流量与待校真空漏孔漏率非常接近,从而避免了四极质谱计的非线性影响.稳压室中的气体压力比较大,所以稳压室不需要特别严格的材料处理工艺,具体校准过程中也不需要彻底的烘烤出气就能得到纯净的单一气体.固定流导法校准真空漏孔的不确定度的评定值为2.6%,可以通过精确校准电容薄膜规和控制温度来进一步降低漏孔校准的不确定度.

STUDY ON METHOD OF CALIBRATING VACUUM LEAK WITH CONSTANT CONDUCTANCE METHOD

Constant conductance method uses partial pressure measurement technology,which has no strict request to outgassing rate of mass spectrum analysis chamber.By experimental research,the measurement error caused by non-linearity of quadrupole mass spectrometer is up to 38%.To eliminate error,the gas pressure in ballast chamber can be adjusted precisely to make gas flow through the orifice very near or equal to the leak rate of calibrated vacuum leak.Moreover,the gas pressure in ballast chamber is high enough that pure single gas can be realized by no strict material disposal and no bakeout.The evaluated uncert ainty is 2.6%for calibration of vacuum leak by constant conductance method,which can be further decreased through precisely calibrating capacitance diaphragm gauge and controlling temperature.