buffer gas

synonym: bath gas
https://doi.org/10.1351/goldbook.12350
Inert gas used for collisional reduction of the internal or translational energy of ions, such as in ion traps.
See also: collision gas
Source:
PAC, 2013, 85, 1515. (Definitions of terms relating to mass spectrometry (IUPAC Recommendations 2013)) on page 1526 [Terms] [Paper]