AVS 66th International Symposium & Exhibition
    Vacuum Technology Division Monday Sessions
       Session VT-MoM

Paper VT-MoM11
Application of Porous Conductance Element for High Vacuum Gauge Calibration

Monday, October 21, 2019, 11:40 am, Room A213

Session: Pumping, Outgassing, leaks, and Vacuum Pressure Measurement
Presenter: Martin-Viktor Johansson, Aix Marseille University, France
Authors: M.V. Johansson, Aix Marseille University, France
M.P. Wüest, INFICON Ltd., Liechtenstein
P. Perrier, Aix Marseille University, France
I. Graur, Aix-Marseille University, France
Correspondent: Click to Email
It is well known that the sensitivity of high vacuum gauges, such as ionization gauges (IG), drift in time [1] and need to be periodically recalibrated. Removal of the sensors from in-situ is time-consuming, and calibration by direct comparison with calibrated IGs has limited accuracy.

The permeability and conductance of the micro sintered stainless-steel membranes with pores varying from 0.2 μm to 0.5 μm was investigated for a wide range of pressure and several gases, from continuum to free molecular regime using a previously developed method [2]. The conductance of this kind of membranes was found constant for low pressures. This property makes the studied membranes particularly suitable as a leak element, by taking advantage of the constancy of conductance in the free molecular regime.

Effective pumping speed of a turbo molecular pump and the conductance of the fabricated microporous conductance element tend to a constant value as the pressure decreases [3], which is still in the measurement range of a 10 mTorr CDG. With the measured constant value, we can use a CDG and the sintered porous stainless steel to calibrate high vacuum sensors. The proposed configuration can be put on the user’s high vacuum system for calibration on site. This calibration method is based on absolute pressure sensors and was found to be robust and easy to use.

References:

[1] H.Yoshida, K.Arai, H. Akimichi, M. Hirata, Stability tests of ionization gauges using two-stage flow-dividing system, Vacuum, 84, 705-708, 2009

[2] M.V. Johansson, F. Testa, I. Zaier, P. Perrier, J.P. Bonnet, P. Moulin, I. Graur, Mass flow rate and permeability measurements in microporous media, Vacuum, 158, 75-85, 2018

[3] H. Yoshida, K. Arai, M. Hirata, H.Akimichi, New leak element using sintered stainless steel filter for in-situ calibration of ionization gauges and quadrupole mass spectrometers, Vacuum, 86, 838-842, 2012