The possibility of the gas generator with a small conductance element made by sintered stainless steel as a small gas flow standard is examined.

 

Helium leak test is one of an important way for the non-destructive testing. Helium standard leaks are usually used for the calibration and for the adjustment of the sensitivity of helium leak detectors．Characteristic and calibration of the helium standard leaks were well studied from late 1980's to middle 1990's1-6). However, the flow ratio of the one unit of standard leak is fixed. Helium flow ratio by the permeation through glass element usually shows large temperature dependence.

 

On the other hand, the gas flow generator composed with a small conductance element made by sintered stainless steel was reported as a variable, stable and wide range gas flow generator for the vacuum gauge calibration7). We examined and made comparison of the helium gas flow ratio between the gas generator and the permeation type helium standard leaks. The flow ratios of the permeation type helium standard leaks are traceable to AIST/NMIJ. The relation of the helium gas flow generated by the generator and the permeation leaks was good agreement with less than 5% of difference. The generator generates wide range of helium gas flow less than 10-5 Pam3/s. This experiment was performed on the ultra high vacuum equipment, which residual pressure was lower than 10-7 Pa, with a quadrupole mass spectrometer. The generator is also useful for the wide range, stable and easy way of calibration of standard leaks. Stability, conformity of the generator is also reported.

 

1) L. E. Bergquist, et al., JVST A 7, 1989, 2414.

2) M. V. Iverson, et al., JVST 20, 1982, 982.

3) J. M. Ball, JVST A 6, 1988, 2860.

4) W. G. Bley, Vacuum 41, 1990, 1863.

5) P. J. Abbott, et al., JVST A 14,1996, 1242.

6) C. D. Ehrlich, et al., JVST A 10, 1992, 1.

7) H. Yoshida, et al., Vacuum 86, 2012, 838.