| CPC H01J 49/063 (2013.01) [F16K 1/2007 (2013.01); H01J 49/005 (2013.01); H01J 49/0077 (2013.01); H01J 49/022 (2013.01); H01J 49/065 (2013.01); H01J 49/067 (2013.01); H01J 49/068 (2013.01); H01J 49/105 (2013.01); H01J 49/421 (2013.01); H01J 49/4215 (2013.01)] | 6 Claims |

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1. An ion optical arrangement for use in a mass spectrometer, comprising:
electrodes defining an ion optical path,
a housing for accommodating the electrodes, the housing including an entrance aperture for ions to enter, an exit aperture for ions to exit, and multiple through holes for gas to exit,
a voltage source for providing voltages to the electrodes to produce electric fields, and
a valve for allowing gas to leave the housing, wherein the valve comprises an electrostatic mechanism; and
wherein the electrostatic mechanism comprises a flexible foil arranged in a spacing between the housing and a support element, the electrostatic mechanism configured for covering the multiple through holes in the housing when a first voltage is applied to the flexible foil and being spaced apart from at least a portion of the multiple through holes to provide a flow path for gas to flow through the multiple through holes and out at least one edge of the flexible foil when a second voltage is applied to the flexible foil.
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