Electron source
AssigneeIsotopx Ltd
InventorsDamian Paul TOOTELL, Anthony Michael JONES
Life of this patent
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Abstract
An electron source in a gas-source mass spectrometer the electron source comprising: an electron emitter cathode presenting a thermionic electron emitter surface in communication with a gas-source chamber of the gas-source mass spectrometer for providing electrons there to; a heater element electrically isolated from the electron emitter cathode and arranged to be heated by an electrical current therein and to radiate heat to the electron emitter cathode sufficient to liberate electrons thermionically from said electron emitter surface, therewith to provide a source of electrons for use in ionising a gas the gas-source chamber.
Claims16
An electron source in a gas-source mass spectrometer the electron source comprising:
- an electron emitter cathode presenting a thermionic electron emitter surface in communication with a gas-source chamber of the gas-source mass spectrometer for providing electrons there to;
- a heater element electrically isolated from the electron emitter cathode and arranged to be heated by an electrical current therein and to radiate heat to the electron emitter cathode sufficient to liberate electrons thermionically from said electron emitter surface, therewith to provide a source of electrons for use in ionising a gas the gas-source chamber.
An electron source according to any preceding claim wherein the gas-source mass spectrometer comprises an electron trap operable to receive electrons from the electron emitter cathode which have traversed the gas-source chamber as a current of at least 0.5 mA in response to the electron emitter cathode being heated by the heater element to a temperature not exceeding 2000° C.
An electron source according to any preceding claim in which the electron emitter cathode is selected from:
- an oxide cathode;
- an I-cathode or Ba-dispenser cathode.
An electron source according to any preceding claim in which the electron emitter cathode comprises a base part which bears a coating of thermionically emissive material presenting the electron emitter surface.
An electron source according to any preceding claim comprising a sleeve which surrounds the heater element, wherein the electron emitter surface resides at an end of the sleeve.
An electron source according to any preceding claim in which the heater element comprises a metallic filament coated with a coating comprising a metal oxide material.
A gas ion source for a mass spectrometer comprising an electron source according to any preceding claim.
Dependencies are inferred from the claim text.