摘要
利用经典的分子流、黏滞流、过渡流流导公式及圆管分子流流导几率的精确数值解,对21世纪数篇文献呈现的漏孔流导随上游压力变化关系曲线进行了分析,并将密封器件的漏孔简化为长圆管,得出了以下结论:从流量角度观察气流是否偏离分子流状态是非常不灵敏的,因此可以认为,如果上游压力不超过1×105Pa,对于等效标准漏率L<1.4 Pa.cm3/s的漏孔,气流大致处于分子流状态;当任务允许的L最大值Lmax 14 Pa.cm3/s时,不论L的值是大是小,均不必考虑气流是否偏离分子流状态;仅在压氦法的压氦阶段,当Lmax和L均接近1.4 Pa.cm3/s时,从流量角度气流会处于黏滞流状态,导致合格判据偏保守;而在压氦法的其他阶段和预充氦法各阶段,只要L<1.4 Pa.cm3/s,气流均处于分子流状态。从而证明对于密封器件氦质谱细检漏而言,Lmax取1.4 Pa.cm3/s可以满足气流处于分子流状态的要求,且该值大于粗检的下限。
The dependence of the conductance of leak on the upstream pressure,reported in the widely-cited literatures in the 21st century,was analyzed with the classic conductance formulae for molecular-flow,viscous-flow and transition-flow,and in terms of the accurate numerical solutions of the conductance probability for molecular-flow in a circular tube.Here,the leak in the hermetically sealed devices was assumed to be a fairly long circular tube.We found that it is highly inappropriate only to evaluate whether the gas flow deviate from the molecular flow from the viewpoint of throughput.So,we concluded that when it comes to the fine leak detection of hermetically sealed devices with the helium mass spectroscopy,either in the pressing or in the pre-filling helium modes,the upper limit of the equivalent standard leakage rate,Lmax,should be 1.4 Pa·cm3/s so as to meet the requirement that the gas flow be in the molecular-flow state,and that the Lmax should be higher than the lower limit of the coarse leak detection.
出处
《真空科学与技术学报》
EI
CAS
CSCD
北大核心
2013年第8期721-729,共9页
Chinese Journal of Vacuum Science and Technology
关键词
氦质谱检漏仪
检漏
密封器件
等效标准漏率
Helium mass spectrometer leak detector
Leak testing
Hermetically-sealed device
Equivalent standard leakage rate
