Patent ID: 6822226
Filing Date: 2004-11-23
Classification: G01N,H01J

Abstract:
Apparatus for ionization of a gas comprising:(a) an ionization region, a reaction region and a drift region; (b) a shutter grid which separates the reaction region from the drift region; (c) a corona ionization source; (d) means for flowing a first gas past the corona ionization source, wherein the first gas is exhausted from the apparatus in the ionization region; (e) means for applying an electric field to move any ions produced by the corona ionization source away from the corona ionization source; (f) means for flowing a second gas through the drift region, wherein the direction of the first gas flow past the corona ionization source is substantially different to the direction of flow of the ions in the electric field and wherein the second gas is exhausted from the apparatus in the drift region.