In-situ calibration method for ionization gauges and quadrupole mass spectrometers by combining the standard conductance element and the conductance modulation method (SCE–CM method)

Abstract

A simple method to generate a standard partial pressure ps by using various gas species has been developed for in-situ calibration of IGs and QMSs. Generating ps requires both introducing a test gas with known flow rate Q and estimating the effective pumping speed S of the high vacuum pump. The former is realized by introducing a test gas through a standard conductance element (SCE) with a molecular flow condition up to the upstream pressure of 104 Pa. The latter is measured by the conductance modulation (CM) method using a gate valve with an orifice. Combination of these two techniques, namely SCE–CM method, enables us to generate ps at the pressure of lower than 10−2 Pa typically for various gas species. Four hot cathode ionization gauges, a spinning rotor gauge (SRG), and two quadrupole mass spectrometers are calibrated by SCE–CM method using 15 gases (H2, He, CH4, H2O, Ne, CO, N2, C2H4, C2H6, O2, Ar, C3H6, CO2, N2O, and C3H8) from 10−6 Pa to 10−2 Pa. The obtained results are consistent with those of previous studies.