Reliability and accuracy of total and partial pressure measurements in the UHV pressure range under real experimental conditions

Comparative tests of Bayerd-Alpert and inverted magnetron gauges from diverse manufacturers were carried out in the laboratory. Commercial residual gas analysers from four different producers were tested to determine (i) linearity, stability and sensitivity of output signals on the pressure response; iii) high-pressure performance; (iii) hysteresis; (iv) fragment ion and electron stimulated desorption (ESD) peaks; (vl detection of small signals. Measurements were performed at different experimental conditions over the pressure range 10(-11)-10(-6) mbar for gases H-2, N-2, Ar and CH4. The pumping system which allows to measure total pressures according to the current in the sputter-ion pump was calibrated and tested during Elettra commissioning. It was observed that the real experimental conditions, e.g. the presence of the radio frequency, radiation, strong magnetic fields can change the interpretation of total and partial pressure measurements significantly. (C) Elsevier Science Ltd. All rights reserved.