CHARACTERISTICS OF COLD-CATHODE GAUGES FOR OUTGASSING MEASUREMENTS INUHV RANGE

Outgassing rates have been evaluated by measuring pressure with hot ca thode gauges as a function of time. However, the large gas release fro m hot cathode gauges and the limited degassing time cause serious erro r in outgassing rate measurements in uhv. Although some investigations were reported on the pumping effects of the gauges with glass tubes, there are few data on the commercially available gauges in this applic ation. In this paper, the gas release and pumping speeds of various co mmercially available gauges are measured quantitatively, including the characteristics of cold cathode/inverted magnetron gauges (IMGs). The maximum pumping speed of the IMGs is 0.1/s-1, and the pumping speed a t pressures in uhv is negligible. It is shown that the IMGs can be uti lized in applications for low outgassing rate measurements in uhv.