Patent ID: 8071941

Claim:
A mass spectrometer arrangement having a detection system ( 12 ) and comprising: a cathode configuration ( 6 ) for emitting electrons ( 21 ); a reaction zone ( 3 ) having an entrance opening ( 14 ) for a supply of neutral particles ( 20 ), the reaction zone being operatively connected to the cathode configuration ( 6 ) for ionization of the neutral particles ( 20 ) in an effective region of the reaction zone to form ions ( 22 ); an ion extraction system ( 4 ) communicating with the effective region of the reaction zone ( 3 ); guidance means ( 1 , 10 , 11 ) for guidance of the ions ( 22 ) to the detection system ( 12 ) within the mass spectrometer arrangement; and evacuation means for evacuation of the mass spectrometer arrangement; the cathode configuration ( 6 ) comprising a field emission cathode with an emitter surface ( 7 ) and, at a short distance from the emitter surface ( 7 ), an extraction grid ( 9 ) for extraction of electrons ( 21 ) away from the emitter surface, the extraction grid substantially covering the emitter surface ( 7 ), and the emitter surface ( 7 ) at least partly encompassing a hollow volume ( 13 ) to create a tubular structure; the reaction zone ( 3 ) being located on a longitudinal axis of the mass spectrometer arrangement and being encompassed by a wall which includes, in a radial direction toward the axis at least one opening, the at least one opening forming a electron extraction lens ( 5 ), the lens being formed in the manner of a chamber enclosing the reaction zone ( 3 ), and the at least one opening communicating with the hollow volume ( 13 ) of the cathode configuration ( 6 ), the wall of the electron extraction lens ( 5 ) being formed in the manner of a chamber that is partially encompassed by the cathode configuration ( 6 ) and is coaxially spaced apart from the cathode configuration ( 6 ) so that the hollow volume ( 13 ) is formed between the cathode configuration ( 6 ) and the electron extraction lens ( 5 ), and in the wall at least one entrance opening ( 14 ) is provided for the introduction of neutral particles ( 20 ).