Remarks concerning about the characteristics of the extractor vacuum gauge and the Quadrupole Mass Spectrometer

The changes in CF of EXG remained within ±5% and ±6%, and fractional changes remained within about ±0.03 and ±0.05 for seven and five different measurement runs for N2 and He, respectively. The change in CF of EXG based on the mean value of the relevant pressure point is 5.8% and 7.8% at 5 × 10−5 Pa, 5.3% and 5.9% at 9 × 10−3 Pa, and maximum CF changes relative to the first calibrations ranges from −1.7% to 2.4% and from −1.0% to 4.7% within the selected pressure range for N2 and He, respectively. The changes of QMS sensitivity are strongly dependent to the electron current. Maximum changes of QMS sensitivities over a three month period are 44% and −35% for N2 and He, respectively. This study was conducted in the frame of EMRP IND12 “Vacuum Metrology for Production Environments” project that was funded by the European Metrology Research Programme (EMRP).