A residual gas analyzer (RGA) is a small, usually rugged, mass spectrometer, typically designed for process control and contamination monitoring in vacuum systems. Using quadrupole technology, two implementations exist; employing either an open ion source or a closed ion source. RGAs may be found in high vacuum applications such as research chambers, surface science setups, accelerators, scanning microscopes, etc.
RGAs are used in most cases to monitor the quality of the vacuum and easily detect minute traces of impurities in the low-pressure gas environment. These impurities can be measured down to 10 Torr levels, possessing sub-ppm detectability in the absence of background interferences. RGAs would also be used as sensitive in-situ, helium leak detectors.
With vacuum systems pumped down to lower than 10 -5 Torr—checking of the integrity of the vacuum seals and the quality of the vacuum—air leaks, virtual leaks, and other contaminants at low levels may be detected before a process is initiated. -14