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)

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.