A dynamic pressure reduction system used for the calibration of a mass spectrometer for argon

Abstract

The probable errors involved in conventional calibration methods (ie the use of a pre-calibrated ionization gauge) are outlined and are shown to be extremely large. A dynamic pressure reduction system is described which allows absolute calibration in the pressure range 1 Nm−2 (~10−2 torr) to 10−6 Nm−2 (~70−5 torr). The reference standard of this system is a McLeod gauge having a sensitivity of 68 Nm−4 (5 The results of an argon calibration for a 60° deflection mass spectrometer are reported and the linearity of the instrument between 10−6 Nm−2 (~10−8- torr) and 10−3 Nm−2 (~10−5 torr) is demonstrated within the limits of experimental error.