EVALUATION OF LOW-COST RESIDUAL-GAS ANALYZERS FOR ULTRAHIGH-VACUUM APPLICATIONS

In recent years several low cost computer controlled residual gas anal yzers (RGAs) have been introduced into the market place. It would be v ery useful to know the performance characteristics of these RGAs in or der to make an informed selection for UHV applications. The UHV applic ations include extreme sensitivity helium leak detection and monitorin g of the residual gas spectra in UHV systems. In this article, the sen sitivity and linearity data for nitrogen, hydrogen, and helium are pre sented in the pressure range 10(-8)-10(-1) Pa. Further, the relationsh ips between focus voltage and ion currents, relative sensitivity, and fragmentation factor are also included. A direct comparison method is used in obtaining this data. Spinning rotor and extractor gauges are t he transfer standard gauges used in Jefferson Lab's vacuum calibration facility, with which all the reported measurements here were carried out. (C) 1997 American Vacuum Society.