Those components used to lower the pressure within a
mass spectrometer are all parts of the vacuum system. This includes not only the various pumping components
but also valves, gauges and associated electronic or other control devices, the chamber
in which ions are formed and detected, and the vacuum envelope.
Source:
PAC, 1991, 63, 1541
(Recommendations for nomenclature and symbolism for mass spectroscopy (including an
appendix of terms used in vacuum technology). (Recommendations 1991))
on page 1546