| AVS 61st International Symposium & Exhibition | |
| Vacuum Technology | Monday Sessions |
| Session VT-MoM |
| Session: | Vacuum Measurement, Calibration, and Primary Standards |
| Presenter: | Janez Setina, Institute of Metals and Technology (IMT), Slovenia |
| Authors: | J. Setina, Institute of Metals and Technology (IMT), Slovenia A. Elkatmis, Ulusal Metroloji Enstitüsü (TUBITAK UME), Turkey R. Kangi, Ulusal Metroloji Enstitüsü (TUBITAK UME), Turkey K. Jousten, Physikalisch-Technische Bundesanstalt (PTB), Germany M. Bergoglio, Istituto Nazionale di Ricerca Metrologica (INRIM), Italy F. Boineau, Laboratoire National de métrologie et d'Essais (LNE), France S. Ruiz, Centro Español de Metrología (CEM), Spain M. Vicar, Czech Metrology Institute (CMI), Czech Republic |
| Correspondent: | Click to Email |
Quadrupole mass spectrometers (QMS) are widely used in industry for leak detection, residual gas analysis and measurements and control of gas composition in vacuum processes, which require well defined partial pressures of different gases in low pressure environment. Consistent measurements and process stability are possible solely if measurement instrumentation is sufficiently stable with time. Only few studies about the time stability of QMS have been reported in the literature. They mainly indicate that QMS instruments are less stable than typical Bayard-Alpert ionization gauges, so frequent recalibrations may be required.
To get information about typical quality of commercial instruments, a group of European national metrology institutes performed a joint study of time stability of some metrological characteristics of seven different QMS. Parameters under study included: sensitivity for gases He and N2, mass resolution, mass scale stability, secondary electron multiplier (SEM) gain, and minimum detectable partial pressure. Typical check intervals were 3 months. Study started in the middle of 2012 and the overall duration was two years.
In 3 months periods the typical changes of sensitivity between 10% and 30% were observed. The peak positions were stable within 0.05 amu and 0.2 amu and mass resolution was stable within 0.02 and 0.05 amu. For most of instruments a gradual decrease of the SEM gain as a result of aging of the multiplier was observed. For some instruments the SEM gain dropped by more than 40 % in 2 years period.
Support through the EMRP IND12 project is gratefully acknowledged. The EMRP is jointly funded by the EMRP participating countries within EURAMET and the European Union.