The Measuring Method of Leak Rate of A Vacuum Chamber Based on Molecular Flow Sensor Element

This article introduces a method for measuring the leak rate of a vacuum chamber based on a molecular flow sensor element.This method measures the overall leak rate of a vacuum chamber through a molecular flow sensor element,the measuring device consists of a gas flow measurement system,a vacuum pumping system,and a constant temperature system.In the measurement system,the gas flow through the sensor element is in the molecular flow regime.By measuring the differential pressure across the sensor element and calculating the mass flow rate,the overall leak rate of the vacuum chamber can be obtained.The measurement results of the leak rate of multiple vacuum chambers in the experiment show that this method can achieve accurate measurement of the leak rate of 10^-5-10^-3 Pa·m³/s.After removing the background leak rate,the measurement results are well fitted with the theoretical results.The measurement results show that the minimum deviation is 0.05% and the maximum is only 0.62%.And by changing the molecular flow sensor element conductance value and differential pressure transmitter range can further expand the measurable range of the method.