| AVS 61st International Symposium & Exhibition | |
| Vacuum Technology | Monday Sessions |
| Session VT-MoM |
| Session: | Vacuum Measurement, Calibration, and Primary Standards |
| Presenter: | Hajime Yoshida, National Institute of Advanced Industrial Science and Technology (AIST), Japan |
| Authors: | H. Yoshida, National Institute of Advanced Industrial Science and Technology (AIST), Japan K. Arai, National Institute of Advanced Industrial Science and Technology (AIST), Japan E. Komatsu, National Institute of Advanced Industrial Science and Technology (AIST), Japan K. Fujii, National Institute of Advanced Industrial Science and Technology (AIST), Japan K. Jousten, Physikalisch-Technische Bundesanstalt (PTB), Germany T. Bock, Physikalisch-Technische Bundesanstalt (PTB), Germany |
| Correspondent: | Click to Email |
International comparison of absolute pressure measurements in gas from 3x10-6 Pa to 9x10-4 Pa, identified as CCM.P-K3, was performed from 1998 to 2002 to determine the degree of equivalence of national metrology institutes (NMIs). A new international comparison, where the pressure range is expanded down to 3x10-9 Pa, is planned as CCM.P-K3 follower. A pilot study was performed in advance because two challenging issues are including the CCM.P-K3 follower. One is the stability of extreme high vacuum (XHV) gauge as a transfer standard. XHV gauges are kinds of hot cathode ionization gauges with a structure to reduce disturbances such as X-ray, electron stimulated desorption (ESD) ion, and so on. Few experiments are reported about the stability of XHV gauges from the viewpoint of metrology. The other is the stability of transfer gauges against to repeating bake-out because baking the calibration chamber including transfer gauges is inevitable to achieve XHV.
At first, three types of XHV gauges; Axial-symmetric transmission gauge (ATG), extractor gauge (EXG), and bent belt-beam gauge (3BG) were tested in NMIJ. Stabilities against air exposure and following bake-out were also tested for both XHV gauges and spinning rotor gauges (SRGs). A protocol for pilot study from 3x10-9 Pa to 9x10-4 Pa was prepared based on the results of both these tests and previous CCM.P-K3. ATG and EXG were adopted as transfer gauges because of achievements so far, although the stabilities of tested XHV gauges were comparable. In addition, two SRGs (SRG-1 and SRG-2) were also adopted as transfer gauges to calibrate at 9x10-4 Pa because stabilities of SRGs were expected to be better than those of XHV gauges. Measurement results of XHV gauges are normalized by those of SRGs. No significant differences of stabilities were observed whether the calibration gas was N2 or Ar. N2 was selected as the calibration gas because N2 is typical calibration gas for ionization gauges.
A bilateral comparison between NMIJ and PTB was performed from May 2013 to Jan 2014 to confirm the effectiveness and to test the transport stability of the transfer standards. Shift of sensitivities of ATG, EXG, SRG-1, and SRG-2 were less than 0.58 %, 0.67 %, 3.5 %, and 0.28 %, respectively. The results of comparison were summarized except for data of SRG-1 because it clearly shows the drift of the sensitivity (effective accommodation coefficient). Results of the comparison show good agreement within the claimed uncertainty. Details will be presented at the conference.