EP0040126B1 - Canon à électrons pour faisceau convergent - Google Patents

Canon à électrons pour faisceau convergent Download PDF

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Publication number
EP0040126B1
EP0040126B1 EP81400666A EP81400666A EP0040126B1 EP 0040126 B1 EP0040126 B1 EP 0040126B1 EP 81400666 A EP81400666 A EP 81400666A EP 81400666 A EP81400666 A EP 81400666A EP 0040126 B1 EP0040126 B1 EP 0040126B1
Authority
EP
European Patent Office
Prior art keywords
electrode
electron gun
point
electron
cathode
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.)
Expired
Application number
EP81400666A
Other languages
German (de)
English (en)
French (fr)
Other versions
EP0040126A1 (fr
Inventor
Bernard Epsztein
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.)
Thales SA
Original Assignee
Thomson CSF SA
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
Application filed by Thomson CSF SA filed Critical Thomson CSF SA
Publication of EP0040126A1 publication Critical patent/EP0040126A1/fr
Application granted granted Critical
Publication of EP0040126B1 publication Critical patent/EP0040126B1/fr
Expired legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J29/00—Details of cathode-ray tubes or of electron-beam tubes of the types covered by group H01J31/00
    • H01J29/46—Arrangements of electrodes and associated parts for generating or controlling the ray or beam, e.g. electron-optical arrangement
    • H01J29/48—Electron guns
    • H01J29/488—Schematic arrangements of the electrodes for beam forming; Place and form of the elecrodes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J29/00—Details of cathode-ray tubes or of electron-beam tubes of the types covered by group H01J31/00
    • H01J29/46—Arrangements of electrodes and associated parts for generating or controlling the ray or beam, e.g. electron-optical arrangement
    • H01J29/56—Arrangements for controlling cross-section of ray or beam; Arrangements for correcting aberration of beam, e.g. due to lenses
    • H01J29/563—Arrangements for controlling cross-section of ray or beam; Arrangements for correcting aberration of beam, e.g. due to lenses for controlling cross-section

Definitions

  • the invention relates to an electron gun.
  • the electron beam produced by the cannon is subjected, in the first part of its path, to the action of means which give it convergence towards a point located at a greater or lesser distance. in front of the cathode.
  • various treatments are applied to it, in relation to the use for which the assembly for which the gun by which it is produced is incorporated. These treatments are outside the scope of the invention.
  • the point of convergence is a point in the geometric sense of the word; in fact, given the mutual repulsion of the charges which compose it, the beam still has at the point of convergence, and whatever the means used, a certain section, the surface of which depends on many parameters, characteristic of the gun.
  • cross-over The electrons, after crossing this zone of minimum section, also known as "cross-over", will form an image of this section on the part of the tube intended to receive their impact, screen, target ...
  • the diameter of this impact depends on that of the "cross-over" in question; it is advantageous to reduce it as much as possible to improve the resolution of the surface subjected to impact and, to do this, to reduce the dimension of the "cross-over".
  • French patent application FR-A-2 201 536 relates to a new structure of electron guns for cathode ray tubes allowing the creation of a second "cross-over". This patent describes the use of a cylindrical anode closed at its two ends by diaphragms.
  • the object of the present invention is to improve an electron gun for a convergent beam provided with means ensuring the maintenance, in the region of the crossing point, of a static distribution of positive ions, the total charge of which is substantially equal in absolute value to that of the beam electrons in this region.
  • the invention relates to an electron gun for a convergent beam, comprising a cathode, first means cooperating with this cathode to produce, inside a vacuum space, an electron beam directed along an axis, and for ensure the convergence of the latter in the first part of its path towards a point of minimum section, and a hollow electrode provided at its ends with orifices to maintain in the vicinity of the point of minimum section the ions created by the shock of electrons of the beam against molecules of residual gas present in the vacuum space characterized in that it comprises, framing said hollow electrode and arranged in its immediate vicinity, two additional electrodes brought to positive potentials relative to said second means.
  • the barrel comprises a cathode 1, heated by a filament 2 in the example; a Wehnelt electrode 3, brought to a negative or zero potential with respect to the cathode taken as a reference, controls the intensity of the beam 6, represented in the figure by the surface covered with dots, emitted by the cathode under the operating conditions , when a positive voltage is applied to the acceleration electrode 8. These conditions are such that the beam converges in its part 10 towards the point bearing the mark 7 in the figure.
  • 20 denotes the vacuum enclosure in which the barrel is housed.
  • the electrode 8 is provided in the form of a hollow electrode surrounding this point of convergence; this electrode is entirely at the same voltage, constant over time.
  • the potential along the electrode 8 is uniform; the production of the beam, by unblocking of the Wehnelt for example, results in a lowering of this potential in the greater part of the electrode 8, where a dip of potential appears; even under the best vacuum conditions, 1.33. 10- 6 to 1,33 - 10- 7 Pa (10- 8 to 10-- 9 torr), in the current state of the art, causes the beam in its path ionization of residual gas molecules present in the vacuum chamber, i.e. the creation of electron (-), ion (+) pairs.
  • the ions on the other hand, attracted by this same space charge, come to mix with the electrons within the beam, and fill the potential trough created by the beam, insofar as they are unable to escape from the electrode 8 through the orifices 81 and 82; we will return to this point later.
  • This situation is that of the permanent regime; it is only reached at the end of the time necessary to generate the ionic charge compensating for that of the beam.
  • This time is of the order of 100 microseconds for a residual pressure of 1.3 - 10 - 6 Pa (10 - 8 torr); it would only be 10 nanoseconds for a pressure of 1.3. ⁇ 10 2 Pa (4 torr 10--) value acceptable for many applications, but which corresponds to a generally incompatible vacuum with a sufficient lifetime of the cathodes due to the intensity of the ion bombardment which they are subjected in this case.
  • the invention provides that, in the case of such a modulation, the electrode which exercises it is placed after the electrode 8 on the path of the beam.
  • This electrode bears the mark 9 in FIG. 2.
  • it may be the grid placed in the immediate vicinity of the target. It may also be, in other cases, a diaphragm associated with the deflector assembly.
  • two additional electrodes, 4 and 5 in the figures can advantageously, in all cases, be used; they are arranged on either side of the electrode 8 in its immediate vicinity, and brought to a positive potential with respect thereto.
  • the electron gun of the invention finds an application, in addition to the aforementioned vidicon tube, in various devices, such as transmission or scanning electron microscopes, electronic probes, etc.
  • the transmission electron microscope is an example of a device free from modulation.

Landscapes

  • Electron Sources, Ion Sources (AREA)
  • Electron Beam Exposure (AREA)
  • Image-Pickup Tubes, Image-Amplification Tubes, And Storage Tubes (AREA)
EP81400666A 1980-05-14 1981-04-28 Canon à électrons pour faisceau convergent Expired EP0040126B1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR8010846 1980-05-14
FR8010846A FR2482778A1 (fr) 1980-05-14 1980-05-14 Canon a electrons pour faisceau convergent, et dispositif, tube vidicon notamment, muni d'un tel canon

Publications (2)

Publication Number Publication Date
EP0040126A1 EP0040126A1 (fr) 1981-11-18
EP0040126B1 true EP0040126B1 (fr) 1985-03-27

Family

ID=9241993

Family Applications (1)

Application Number Title Priority Date Filing Date
EP81400666A Expired EP0040126B1 (fr) 1980-05-14 1981-04-28 Canon à électrons pour faisceau convergent

Country Status (5)

Country Link
US (1) US4486687A (enrdf_load_stackoverflow)
EP (1) EP0040126B1 (enrdf_load_stackoverflow)
JP (1) JPS577052A (enrdf_load_stackoverflow)
DE (1) DE3169503D1 (enrdf_load_stackoverflow)
FR (1) FR2482778A1 (enrdf_load_stackoverflow)

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0355234Y2 (enrdf_load_stackoverflow) * 1984-09-27 1991-12-09
NL8403537A (nl) * 1984-11-21 1986-06-16 Philips Nv Kathodestraalbuis met ionenval.
US5287038A (en) * 1992-05-14 1994-02-15 Litton Systems, Inc. High resolution electron gun
DE10242708A1 (de) 2002-09-13 2004-05-19 Celanese Ventures Gmbh Protonenleitende Membranen und deren Verwendung

Family Cites Families (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2172530A (en) * 1936-01-24 1939-09-12 Cathode bay tube
DE912725C (de) * 1940-05-31 1954-06-03 Rca Corp Kathodenstrahlroehre, insbesondere Projektionsroehre
US3141993A (en) * 1959-12-24 1964-07-21 Zeiss Jena Veb Carl Very fine beam electron gun
FR2201536B1 (enrdf_load_stackoverflow) * 1972-09-26 1976-08-13 Thomson Csf
US3904913A (en) * 1973-08-27 1975-09-09 Raytheon Co Focusing means for cathode ray tubes
US3924153A (en) * 1974-03-11 1975-12-02 Westinghouse Electric Corp Electron gun
US4044282A (en) * 1974-10-17 1977-08-23 Balandin Genrikh D Cathode-ray tube with variable energy of beam electrons
US4075533A (en) * 1976-09-07 1978-02-21 Tektronix, Inc. Electron beam forming structure utilizing an ion trap
JPS5416623U (enrdf_load_stackoverflow) * 1977-07-02 1979-02-02
NL7809345A (nl) * 1978-09-14 1980-03-18 Philips Nv Kathodestraalbuis.

Also Published As

Publication number Publication date
FR2482778B1 (enrdf_load_stackoverflow) 1982-10-01
FR2482778A1 (fr) 1981-11-20
US4486687A (en) 1984-12-04
DE3169503D1 (en) 1985-05-02
JPS577052A (en) 1982-01-14
EP0040126A1 (fr) 1981-11-18

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