Inficon Gmbh

Wolfram Knapp

Martin Wüest

A cathode configuration for emission of electrons has a reaction zone connected to an entrance opening for the supply of neutral particles. The opening communicates with the cathode configuration for the ionization of the neutral particles and an ion extraction system communicates with the reaction zone. Ions from the extraction system are sent to a detection system and a mechanism for the evacuation of the mass spectrometer arrangement. The cathode configuration includes a field emission cathode with an emitter surface, wherein at a short distance from this emitter surface, an extraction grid is disposed for the extraction of electrons, which grid substantially covers the emitter surface. The emitter surface encompasses herein at least partially a hollow volume such that a tubular structure is formed.

Mass spectrometer

A vacuum pressure measuring device with an electron source has a reaction zone for forming ions by impact ionization, wherein the electron source communicates with the reaction zone via a passage for the electrons. The electron source is surrounded by an insulating housing with a vacuum chamber, and a partition part is designed as a membrane carrier, carrying a nanomembrane at least in one section, the membrane separating the vacuum chamber from the outer region in a gastight manner and being at least partially designed to be electron-permeable. The vacuum chamber has a cathode for the emission of electrons. In the region of and/or on the nanomembrane, an anode arrangement is provided such that electrons are conducted against the nanomembrane and at least partially through it. The nanomembrane abuts the vacuum chamber of the vacuum pressure measuring device.

Electron source for a vacuum pressure measuring device

An electron-emitting cathode consists of an electrically conducting emitter layer attached to a side wall which consists of stainless steel and a gate which is fixed at a mall distance inside a concave emitter surface of the emitter layer. The cathode surrounds a reaction area containing a cylindrical grid-like anode and a central ion collector which consists of a straight axial filament. An ion collector current reflecting the density of the gas in the reaction region is measured by a current meter while a gate voltage is kept between the ground voltage of the emitter layer and a higher anode voltage and is regulated in such a way that an anode current is kept constant. The emitter layer may consists of carbon nanotubes, diamond-like carbon, a metal or a mixture of metals or a semiconductor material, e.g., silicon which may be coated, e.g., with carbide or molybdenum. The emitter surface can, however, also be a portion of the inside surface of the side wall roughened by, e.g., chemical etching. The gate may be a grid or it may be made up of patches of metal film covering spacers distributed over the emitter area or a metal film covering an electron permeable layer placed on the emitter surface.

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Moser, Germany

Wolfram Knapp