超高/极高真空校准装置的研制

Calibration of Ultra High and Extra High Vacuum

超高/极高真空校准装置由极高真空(XHV)系统、超高真空(UHV)系统、流量分流系统和供气系统四部分组成。使用磁悬浮涡轮分子泵和非蒸散型吸气剂泵组合抽气,在XHV校准室获得了10-10Pa的极高真空;提出了分流法校准真空规的方法,使校准下限延伸到10-10Pa;利用非蒸散型吸气剂泵对惰性气体无抽速的特性,使用惰性气体校准时,减小了校准下限的不确定度;提出了采用线性真空计测量激光小孔分子流流导的方法,减小了小孔流导的测量不确定度。校准装置复合了分流法、压力衰减法和直接测量法对真空规进行校准,压力校准范围为10-1Pa^10-10Pa,合成标准不确定度为0.41%~3.5%。

A novel technique has been successfully developed to calibrate the ultra high vacuum（UHV） and extra high vacuum（XHV）, which consists of XHV/UHV chambers, a flow separation and a gas supply, First, the upper hmit of 10^- l0 Pa base pressure in the XHV calibration chamber was pumped by magnetically levitated turbo-molecular pump combined with non-evapomble getter（NEG） pump, Next, the flow separation was used to extrapolate the lower limit of the gauge calibration to 10^- l0 Pa. Since NEG pump fails to pump any inert gas,the uncer tainty at lower limit decreases when inert gas acts as the test gas. Finally, the evaluation of the molecular flow conductance of a laser orifice with a linear vacuum gauge further reduces the uncertainty of the orifice conductance measurement. The calibration technique integrates three methods available：flow separation, pressure attenuation,and direct measurenment,to calibrate the vaecum gauge. The gauge calibration ranges from 10^-1 Pa to 10^-10 Pa with a combined standard uncertainty in the range of 0.41% - 3.5%.