Patent ID: 9741549
Date: 2017-08-22
CPC Classifications: H01J

Claim:
1. A method of operating a mass spectrometer vacuum interface comprising a skimmer apparatus having an internal surface and a skimmer aperture and downstream ion extraction optics, the method comprising: skimming an expanding plasma through the skimmer aperture, and separating within the skimmer apparatus a portion of the skimmed plasma adjacent the skimmer apparatus from the remainder of the skimmed plasma by providing means to prevent the separated portion from reaching the ion extraction optics while allowing the remainder to expand towards the ion extraction optics, wherein the means comprises one or more channels provided by a channel-forming member disposed within a recess in the internal surface of the skimmer apparatus and in conductive contact with the skimmer apparatus whereby the channel member is electrically neutral relative to the skimmer apparatus and the portion of the skimmed plasma adjacent the skimmer apparatus is separated by diverting the portion into the one or more channels.