EP0300932A1 - ELektronenquelle - Google Patents

ELektronenquelle Download PDF

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Publication number
EP0300932A1
EP0300932A1 EP88420256A EP88420256A EP0300932A1 EP 0300932 A1 EP0300932 A1 EP 0300932A1 EP 88420256 A EP88420256 A EP 88420256A EP 88420256 A EP88420256 A EP 88420256A EP 0300932 A1 EP0300932 A1 EP 0300932A1
Authority
EP
European Patent Office
Prior art keywords
anode
cathode
opening
electron source
plasma
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
EP88420256A
Other languages
English (en)
French (fr)
Other versions
EP0300932B1 (de
Inventor
Jacques Menet
Olivier De Gabrielli
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Centre National de la Recherche Scientifique CNRS
Original Assignee
Centre National de la Recherche Scientifique CNRS
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
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Publication of EP0300932A1 publication Critical patent/EP0300932A1/de
Application granted granted Critical
Publication of EP0300932B1 publication Critical patent/EP0300932B1/de
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J3/00—Details of electron-optical or ion-optical arrangements common to two or more basic types of discharge tubes or lamps
    • H01J3/02—Electron guns
    • H01J3/025—Electron guns using a discharge in a gas or a vapour as electron source

Definitions

  • the present invention relates to an electron source for an electron gun.
  • thermoelectronic source those with thermoelectronic source and those in which the source is a plasma.
  • FIG. 1 very schematically represents an electron gun with plasma source.
  • This electron gun comprises a cathode plate K opposite an anode plate A.
  • the conditions of electric field and gas pressure between the cathode and the anode are chosen so that a luminescent discharge is obtained in the area between these plates. In practice, this means that there must be a minimum field of the order of a few hundred V / cm and a pressure of the order of 1 to 10 Pa.
  • a plasma P is created between cathode and anode and electrons strike the anode plate.
  • This anode plate A is provided with a central opening through which the electrons can escape which are then accelerated by various means towards a collecting plate C.
  • the pressure in the area between the anode plate A and the plate must be collector C is sufficiently low.
  • the pressure must be less than 0.1 Pa.
  • FIG. 1 The structure of Figure 1 is extremely schematic. In practical devices, numerous improvements are provided, for example electrodes intermediate between cathode and anode. These electrodes can take the form of grids. Similarly, to maintain good focusing of the electron beam in the acceleration zone, it is sometimes planned to use magnetic fields parallel to the direction of propagation of the electrons.
  • thermoelectronic sources have the advantage over thermoelectronic sources of a longer service life and the possibility of operating at higher pressure (1 to 10 Pa instead of 10 ⁇ 4 to 10 ⁇ 3 Pa).
  • a first drawback lies in the fact that, since a plasma is created in the entire area between the cathode and the anode, the efficiency of the device is necessarily less than unity since part of the electrons will strike the anode plate A. This loss can be reduced by using, instead of a simple opening as shown in FIG. 1, a transparent anode system provided with magnetic focusing. However, we are left with yields lower than one, for example of the order of 70%.
  • an object of the present invention is to provide a new type of plasma electron source overcoming the drawbacks exposed above of conventional plasma electron sources.
  • the present invention provides an electron source comprising, in a low pressure enclosure, an anode, a cathode and means for applying a magnetic field, in which the cathode is consisting of an equipotential cavity provided with an opening on the anode side and a magnetic field parallel to the anode-cathode direction is applied at the opening.
  • the pressure in the enclosure is of the order of a few tenths of pascal.
  • the voltage applied between the anode and the cathode is of the order of a few hundred volts / cm.
  • the magnetic field is of the order of a few hundredths of a tesla.
  • the opening is a very long slot.
  • the device according to the present invention makes it possible to have an electron gun having in particular the following advantages: - theoretical yield equal to 1, - delineation of the electron beam independently of the anode structure and the focusing structures, - Ability to operate at a pressure of the order of a few tenths of pascal in the plasma creation zone, which is compatible with the pressure allowed in the acceleration zone.
  • the electron source according to the present invention comprises a cathode K and an anode A.
  • the cathode K consists of an equipotential cavity 10 provided with an opening 11 on the side of the anode A.
  • Means, for example, permanent magnets, are provided to apply a magnetic field B in the cathode-anode direction at the opening 11.
  • the plasma is created whatever the shape and size of the opening.
  • the efficiency between the electron current and the discharge current is close to 100%;
  • the plasma can be created at a pressure of the order of a few tenths of pascal;
  • the system is of a very simple structure and should be able to be manufactured at low cost compared to existing electron guns.
  • FIG. 3 represents a plasma electron source according to the present invention associated with an accelerating cavity.
  • the cathode K consisting of a cavity 10 and the anode A.
  • the anode A is provided with an opening 20 to let the electrons pass to an accelerating electrode C.
  • a transparent anode could be provided, that is to say for example an anode constituted by a grid.
  • the advantage of the present invention in relation to an accelerating cavity lies in particular in the fact that the entire system can operate at a single pressure and therefore that it is no longer necessary to provide sophisticated pumping systems.
  • the cathode cavity can be rectangular with a width of 50 mm and a depth of 10 mm, the slot having a width of a few mm and a length of 100 mm.
  • the anode-cathode voltage is of the order of 400 V and the magnetic field of 8 x 10 ⁇ 2 tesla, the intensity of the electron beam being 1.5 A.
  • the present invention is susceptible of numerous variants consisting notably in adapting to it the conventional variants of known plasma electron sources.
  • intermediate grids can be provided in the cathode-anode zone, more sophisticated focusing systems can be provided in the accelerating zone, and, if desired, a pressure difference can be provided between the plasma creation zone and the accelerating zone and this pressure difference will be easier to apply than in the prior art because of the lower pressure in the plasma creation zone.

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  • Plasma Technology (AREA)
  • Particle Accelerators (AREA)
  • Electron Sources, Ion Sources (AREA)
EP88420256A 1987-07-22 1988-07-20 ELektronenquelle Expired - Lifetime EP0300932B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR8710642A FR2618602B1 (fr) 1987-07-22 1987-07-22 Source d'electrons
FR8710642 1987-07-22

Publications (2)

Publication Number Publication Date
EP0300932A1 true EP0300932A1 (de) 1989-01-25
EP0300932B1 EP0300932B1 (de) 1992-01-29

Family

ID=9353612

Family Applications (1)

Application Number Title Priority Date Filing Date
EP88420256A Expired - Lifetime EP0300932B1 (de) 1987-07-22 1988-07-20 ELektronenquelle

Country Status (5)

Country Link
US (1) US4886992A (de)
EP (1) EP0300932B1 (de)
JP (1) JPH01126598A (de)
DE (1) DE3868169D1 (de)
FR (1) FR2618602B1 (de)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2639756B1 (fr) * 1988-11-30 1994-05-13 Centre Nal Recherc Scientifique Source de vapeurs et d'ions
JP5378723B2 (ja) * 2007-07-27 2013-12-25 矢崎総業株式会社 電子線照射装置及び被覆電線の製造方法

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR1281964A (fr) * 1960-11-18 1962-01-19 Csf Nouvelle cathode à grand pouvoir émissif
FR2498010A1 (fr) * 1981-01-12 1982-07-16 Kreindel July Source d'electrons et d'ions

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3381157A (en) * 1964-12-10 1968-04-30 United Aircraft Corp Annular hollow cathode discharge apparatus
JPS4928718A (de) * 1972-07-17 1974-03-14
JPS5349B2 (de) * 1972-07-19 1978-01-05
US4633129A (en) * 1985-04-30 1986-12-30 International Business Machines Corporation Hollow cathode

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR1281964A (fr) * 1960-11-18 1962-01-19 Csf Nouvelle cathode à grand pouvoir émissif
FR2498010A1 (fr) * 1981-01-12 1982-07-16 Kreindel July Source d'electrons et d'ions

Also Published As

Publication number Publication date
DE3868169D1 (de) 1992-03-12
US4886992A (en) 1989-12-12
FR2618602B1 (fr) 1990-01-05
JPH01126598A (ja) 1989-05-18
FR2618602A1 (fr) 1989-01-27
EP0300932B1 (de) 1992-01-29

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