基于静态累积法的极小气体流量测量研究

Research on Measurement of Very Low Gas Flow based on Static Cumulative Method

通过静态膨胀法与固定流导法获得了(10^(-9)~10^(-14))Pam^(3)/s的氦标准气体流量,并采用静态累积法对所产生的极小气体流量进行了测量,相应的氦离子流上升率在(10^(-10)~10^(-15))A/s范围。实验结果表明:气体流量静态累积时的离子流波动随流量降低逐渐增大,降至1.69×10^(-14)Pam^(3)/s时,多个数据点已偏离上升率拟合线较远,此时达到测量下限。在(10^(-9)~7.66×10^(-12))Pam^(3)/s范围,气体流量与对应离子流上升率有很好的线性,最大偏差为6.8%;当气体流量小于7.66×10^(-12)Pam^(3)/s时,标准流量与离子流上升率的对应关系呈现出明显的非线性。

He standard gas flow in the range of(10^(-9)~10^(-14))Pam^(3)/s were obtained by static expansion method and constant conductance method.The generated very low gas flow was measured by static cumulative method where the corresponding He ion current increase rate varied from 10-10 to 10-15 A/s.The experimental results show that the wave motion of the ion current increases with the decrease of gas flow rate.When the flow drops to 1.69×10^(-14) Pam^(3)/s,several data points have deviated from the increase rate fitting line indicating that the lower limit of measurement has been reached.For gas flow rates from 10-9 Pam^(3)/s to 7.66×10^(-12) Pam^(3)/s,their corresponding He ion current rates displayed good consistency with theoretical value,where the maximum deviation from linearity is 6.8%.However,once the flow rate drops below 7.66×10^(-12) Pam^(3)/s,the collected ion current increase rate data clearly diverge from the linear fitting.