Measurement apparatus and method for minimum vacuum leak rate

Abstract

The invention discloses a measurement apparatus and method for a minimum vacuum leak rate. According to the method, a calibration chamber pressure is maintained to a background pressure and measurement and calculation are carried out to obtain a rise rate R0 of a background ion current of the calibration chamber; a calibrated vacuum standard leak hole flow is introduced into the calibration chamber to carry out static accumulation, and measurement and calculation are carried out to obtain a rise rate RL of an ion current containing the calibrated vacuum standard leak hole flow and the background; a standard flow of a known floe QS is led into the calibration chamber to carry out static accumulation, and measurement and calculation are carried out to obtain a rise rate RS of an ion current containing the standard flow and the background; and then a leak rate QL of the calibrated vacuum standard leak hole is calculated based on a formula: QL / QS=(RL-R0) / (RS-R0). With the method, flow conductance ratio measurement can be avoided. The method and apparatus are suitable for measurement and calibration of a minimum vacuum leak rate; and thus the measurement and calibration lower limits of the minimum vacuum leak rate are extended and a foundation is provided for precise measurement and calibration of a minimum vacuum leak rate less than 1*10<9>Pa.m<3> / s.

Description

technical field [0001] The invention belongs to the field of measurement, and relates to a measurement technology of a very small vacuum leak rate, in particular to a device and a method for realizing precise measurement of a very small vacuum leak rate by adopting a static accumulation method. Background technique [0002] In metrology laboratories, high-precision gas micro-flow meters are mostly used to measure and provide known gas flow rates. High-precision gas micro-flow meters mostly use constant-pressure gas micro-flow meters and fixed conductance gas micro-flow meters, and their measurement range is (1×10 -9 ~1×10 -4 )Pa·m 3 / s. When the dynamic flow method is used to calibrate, due to the influence of the gas micro-flowmeter pipe inner wall degassing effect, the flow measurement lower limit is only 1×10 -9 Pa·m 3 / s, so the calibration of the extremely small vacuum leak rate cannot be realized with the existing gas micro flowmeter. [0003] The literature "Li ...

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Problems solved by technology

[0004] Whether it is the shunt method or the dynamic flow method, it is necessary to measure the conductance ratio of the two small holes on the shunt chamber, and the measurement of the conductance ratio will cause a large measurement uncertainty

Moreover, when the vacuum leak rate is extremely small, the mass spectrometer cannot distinguish the calibrated ion flow from the background ion flow, which will also lead to a large measurement uncertainty, or even fail to complete the measurement.

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