Partial Pressure Calibration For Residual Gas Analyzers

Abstract

The method of reference transfer is applied to the full range partial pressure calibration of residual gas analyzers (RGA). Partial pressures are transferred across the upper orifice of a 10× pressure divider in such a way that a mathematically interrelated series of increasing partial pressures is generated. A gas flow measurement is used to establish the value of the partial pressure when it is in the 10−5 to 10−7 Torr region. For gases not residual to the vacuum system, calibration can begin at pressure levels limited primarily by electronic sensitivity and noise. Independence of RGA peak heights from interference by certain other gases was observed over a wide range of partial pressures of the several gases. Using this same equipment, inert gas fixed leaks were calibrated for just the inert gas components of their effluent.