Ion source for time-of-flight mass spectrometers for analyzing gas samples

• US 6,545,269 B1
• Filed: 04/14/2000
• Issued: 04/08/2003
• Est. Priority Date: 04/22/1999
• Status: Expired due to Fees

• Current Assignee: Alcatel SA (Nokia Corporation)
• Original Assignee: Alcatel SA (Nokia Corporation)
• Inventors: Pierrejean, Didier, Galland, Bruno
• Primary Examiner(s): NGUYEN, KIET TUAN
• Application Number:
  US09/550,171
• Publication Number:
  US 20030057378A1
• Time in Patent Office: 1,089 Days
• Field of Search: 250/423.R, 250/427, 250/288, 250/287
• US Class Current: 250/288
• CPC Class Codes: H01J 27/04 using reflex discharge, e.g. Penning ion sources electron bombardment ion sources H01J27/08
• CPC Class Codes: H01J 43/246 Microchannel plates [MCP] image amplification tubes using MCP H01J31/507
• CPC Class Codes: H01J 49/08 Electron sources, e.g. for generating photo-electrons, secondary electrons or Auger electrons
• CPC Class Codes: H01J 49/10 Ion sources; Ion guns
• CPC Class Codes: H01J 49/147 with electrons, e.g. electron impact ionisation, electron attachment H01J49/145 takes precedence

Abstract

In accordance with the invention, the ion source of a time-of-flight mass spectrometer includes an electron gun having an electron source and at least one electrode for conditioning the flow of electrons, followed by at least one microchannel wafer for generating a pulsed secondary electron beam containing a greater number of electrons from a pulsed primary electron beam. The secondary electron beam enters a gas ionization area of an ion gun which produces a flow of ions which is then passed through the flight tube in order to be analyzed by an ion detector. This provides a high-performance ion source which is compact, sensitive and easy to integrate.

Claims

1. An ion source for mass spectrometers, the source including an electron gun having an electron source and at least one electron conditioning electrode which generates a flow of electrons directed towards a gas ionization area in which ions are formed which are acted on by at least one ion conditioning electrode, wherein at least one microchannel wafer is disposed in the flow of electrons downstream of said at least one electron conditioning electrode and generates a secondary electron beam, and wherein there is provided an additional electrode downstream of the area occupied by said at least one microchannel wafer for dispersing the secondary electron beam to retain temporal properties and improve spatial properties of the secondary electron beam.

2. An ion source according to claim 1, wherein the gas ionization area is between an upstream repulsion electrode through which the secondary electron beam is passed and which retains the electrons by repelling the ions and a downstream acceleration electrode which attracts the ions.

3. An ion source according to claim 1, the ion source being aligned with the entry of the flight tube of a time-of-flight mass spectrometer.

4. An ion source according to claim 1, wherein the gas ionization area is in the immediate vicinity of the microchannel wafer.

5. An ion source according to claim 1, wherein the electron source is a filament heated to an appropriate temperature to generate a flow of electrons by thermal emission and the primary electron beam is pulse modulated by a deflector electrode.

6. An ion source according to claim 1, wherein the electron source is a micropoint-type field-emission cathode producing a pulse modulated primary electron beam.

7. A time-of-flight mass spectrometer including an ion source according to claim 1.

8. An ion source for mass spectrometers, the source including an electron gun having an electron source and a electron conditioning means for conditioning a flow of electrons to generate a flow of electrons directed towards a gas ionization area in which ions are formed which are acted on by at least one ion conditioning means for conditioning the flow of ions, wherein at least one wafer means for conditioning the flow of electrons is disposed in the flow of electrons downstream of said first electron conditioning means and generates a secondary electron beam, and wherein there is provided means for dispersing the secondary electron beam to retain temporal properties and improving spatial properties of the secondary electron beam.

9. An ion source for mass spectrometers, the ion source including an electron gun having an electron source and at least one electron conditioning electrode which generates a flow of electrons directed towards a gas ionization area in which ions are formed which are acted on by at least one ion conditioning electrode, wherein at least one microchannel wafer is disposed in the flow of electrons downstream of said at least one electron conditioning electrode and generates a secondary electron beam wherein there is provided an additional electrode downstream of the area occupied by said at least one microchannel wafer for dispersing the secondary electron beam to retain temporal properties and improve spatial properties of the secondary electron beam, and wherein the ion source is aligned with an entry of a flight tube of a time-of-flight mass spectrometer.