Applied Science and Convergence Technology 2015; 24(4): 84-89
Published online July 31, 2015
Copyright © The Korean Vacuum Society.
Chongdo Parka, Taekyun Haa, and Boklae Chob*
aPohang Accelerator Laboratory, POSTECH, Pohang 790-784, Korea
bKorea Research Institute of Standards and Science, Daejeon 305-340, Korea
Correspondence to:Boklae Cho
This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
The base pressure and outgassing rate of a mild steel chamber were measured and compared to those of a stainless steel chamber. A combined sputter-ion and non-evaporable getter pump with a nominal pumping speed of 490 l/s generated the base pressure of 2.7×10−11 mbar in the mild steel chamber and 1.2×10−10 mbar in the stainless steel chamber. The rate-of-rise measurements show that the mild steel has an extremely low outgassing rate of 2.6×10−13 mbar l s−1 cm−2, which is about one-order of magnitude smaller than the outgassing rate of the stainless steels. Vacuum annealing of the mild steel at 850°C reduced the outgassing rate further to 8.8×10−14 mbar l s−1 cm−2, which was comparable to the outgassing rate of a heat treated stainless steel for extreme-high vacuum use.
Keywords: Outgassing rate, Mild steel, UHV