EP0003937A2 - Kathode für eine Elektronenkanone - Google Patents

Kathode für eine Elektronenkanone Download PDF

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Publication number
EP0003937A2
EP0003937A2 EP79400126A EP79400126A EP0003937A2 EP 0003937 A2 EP0003937 A2 EP 0003937A2 EP 79400126 A EP79400126 A EP 79400126A EP 79400126 A EP79400126 A EP 79400126A EP 0003937 A2 EP0003937 A2 EP 0003937A2
Authority
EP
European Patent Office
Prior art keywords
pellet
cathode according
cathode
resistor
resistance
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
EP79400126A
Other languages
English (en)
French (fr)
Other versions
EP0003937A3 (en
EP0003937B1 (de
Inventor
Gérard Marhic
Philippe Martin
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.)
Commissariat a lEnergie Atomique et aux Energies Alternatives CEA
Original Assignee
Commissariat a lEnergie Atomique CEA
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 Commissariat a lEnergie Atomique CEA filed Critical Commissariat a lEnergie Atomique CEA
Publication of EP0003937A2 publication Critical patent/EP0003937A2/de
Publication of EP0003937A3 publication Critical patent/EP0003937A3/fr
Application granted granted Critical
Publication of EP0003937B1 publication Critical patent/EP0003937B1/de
Expired 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
    • H01J3/027—Construction of the gun or parts thereof
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J1/00—Details of electrodes, of magnetic control means, of screens, or of the mounting or spacing thereof, common to two or more basic types of discharge tubes or lamps
    • H01J1/02—Main electrodes
    • H01J1/13—Solid thermionic cathodes
    • H01J1/15—Cathodes heated directly by an electric current
    • H01J1/16—Cathodes heated directly by an electric current characterised by the shape

Definitions

  • the present invention which results from the work carried out by Mr. sympathy MARHIC of the AUTOGENE FRENCH WELDING essentially relates to a cathode for electronic gun comprising at least one pellet made of a material capable of emitting, at high temperature, electrons, for example lanthanum hexaboride (LaE6) and at least one heating resistor made of a material with high electrical resistivity, for example pyrolitic graphite, said pellet and said resistance being traversed, in series, by an electric heating current.
  • LaE6 lanthanum hexaboride
  • the cathode constitutes the electron generator of cannons mounted on various devices using electron beams.
  • the emitted electrons are subjected to the action of the Wehnelt which regulates the power of the beam, accelerated by a voltage established between the cathode and an anode and finally focused by a magnetic lens which makes them converge on a practically point surface.
  • Cathodes of the aforementioned type are already known which are essentially constituted by a LaB6 emitting pellet having, at least in part, the shape of a rectangular parallelepiped and by two blocks of pyrolitic graphite, cubic in shape, placed on either side. other of the emitting tablet.
  • the whole is mounted on a fixed support comprising two metal arms connected to a source of electrical energy, these two arms being in direct contact with the graphite blocks and pressing them against the emitting pad which is interposed between them.
  • the invention aims to overcome these drawbacks and offers this offer a cathode whose pellet is in the form of a hollow part mounted on a support integral with the barrel, in which is engaged and against a wall of which is applied the resistance of pyrolitic graphite.
  • Heat transmission is therefore not only by ccnduction between the contacting surfaces but also by radiation since most of the radiation emitted by the resistor meets the pellet. This results in a better efficiency of the cathode.
  • the pellet and the resistor are in the form of a part of revolution, the axes of these parts being in coincidence when the resistor is engaged in the pellet.
  • the pellet is in the form of a cup provided with a flat bottom wall and a side wall flaring from said bottom wall and the resistance is in the form of a truncated cone whose small base is applied against the bottom of the cup.
  • the cathode comprises a sheath made of an electrically conductive and chemically inert material with respect to LaB6, for example in graphite and inside which said pellet is inserted.
  • This sheath is mounted directly on the aforementioned support.
  • the sheath makes it possible to maintain the pellet without it being necessary to weld it to the support, thus eliminating any chemical reaction between LaB6 and the material of said support.
  • the sheath also ensures the conduction of the heating current.
  • the resistance is applied against the bottom wall of the pellet by elastic means.
  • the cathode according to the invention is housed inside a cylindrical barrel shown schematically in 2 and fixed to a support plate integral with the latter and shown diagrammatically in 3.
  • the barrel 2 comprises, in a manner known per se, a certain number of other elements, in particular one or more magnetic lenses, an anode and a Wehnelt, only the latter being represented in 4.
  • the barrel 2 and all of the elements which it comprises admit the axis XX 'as the axis of revolution.
  • the cathode 1 essentially consists of an emitting patch 10 made of LaB6, housed in a sheath 11 mounted on a support 12 fixed itself on the support plate 3 of the barrel 2 and of a heating resistor 14.
  • the patch and the sheath are housed in the central opening 4a of Wehnelt 4.
  • the emitting pad 10 is constituted by a hollow part of revolution and has the shape of a bowl provided with a flat bottom wall 10a and a side wall 10b flared outwards.
  • the sheath 11 in which the pellet 10 is housed is made of graphite and has the shape of a tubular cylinder of revolution. It is provided, at its upper end, with a lip or the like 11a, projecting inwards, against which the external face 10c of the patch 10 is supported and at its lower part, with a flange 11b projecting outwards which rests on the support 12.
  • the support 12 is constituted by two front and rear frustoconical capsules 12a and 12b respectively, these capsules being joined by their large bases and fixed by the latter to the support plate 3.
  • the resistor 14 made of pyrolitic graphite, has the general shape of a truncated cone whose small and large bases are designated respectively by 14a and 14b and is further provided with an axial recess 14c.
  • the resistor 14 is in abutment, by its small base 14a in the form of a crown, against the flat bottom 10a of the pellet.
  • the bottom of 10a and the small base 14a are given substantially equal diameters and the conical resistor 14 an angle at the top substantially less than that of the flared edge 10b of the patch.
  • the resistance 14 is applied against the pellet by a rod or pusher 15 provided, at its upper end, with a head 15a resting on its large base 14b.
  • the pusher 15 is secured, by means of a first metal ring 16, to a first tubular element 17 of axis XX ′ inside which it is housed, this first tubular element 17 being itself secured by through an insulating ring 18, a second tubular element 19 of axis XX 'in which it is housed.
  • the tubular element 19 is itself mounted on a support rod 20.
  • the plunger 15 and the tubular elements 17 and 19 constitute a rigid assembly which has the function of transmitting to the resistor 14 the thrust of elastic means.
  • These elastic means consist of a corrugated sheath or bellows 23 of axis XX ′ and surrounding the annular element 19.
  • the sheath 23 is fixed, at its upper part 23 a, to the capsule 12 b of the support 12 and is provided, at its lower end 23b of an annular stop 24 which bears, by means of an insulating ring 25, for example made of alumina against the end of the element 19.
  • the assembly constituted by the pusher 15 and the tubular elements 17 and 19 also has the function of creating, between the resistance heater 14 whose temperature is of the order of 1700 ° and the corrugated sheath 23, a substantial decrease in temperature so that said corrugated sheath as well as the support rod 20 reach a temperature of the order of 200 to 300 ° C. .
  • the cathode is also provided with frustoconical screens 26 and 27 located respectively inside and outside the capsule 12.
  • the elastic support provided by the corrugated sheath 23 protects the pellet and the resistance from mechanical stresses encountered with rigid systems, which makes it possible to significantly increase the service life of the cathode. .
  • the invention applies to all devices using electron beam generators, in particular to electron bombardment welding devices and electron microscopes.

Landscapes

  • Solid Thermionic Cathode (AREA)
  • Electron Sources, Ion Sources (AREA)
  • Thermistors And Varistors (AREA)
EP79400126A 1978-03-01 1979-02-28 Kathode für eine Elektronenkanone Expired EP0003937B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR7805813A FR2418964A1 (fr) 1978-03-01 1978-03-01 Cathode pour canon electronique
FR7805813 1978-03-01

Publications (3)

Publication Number Publication Date
EP0003937A2 true EP0003937A2 (de) 1979-09-05
EP0003937A3 EP0003937A3 (en) 1979-09-19
EP0003937B1 EP0003937B1 (de) 1980-10-15

Family

ID=9205196

Family Applications (1)

Application Number Title Priority Date Filing Date
EP79400126A Expired EP0003937B1 (de) 1978-03-01 1979-02-28 Kathode für eine Elektronenkanone

Country Status (5)

Country Link
US (1) US4220889A (de)
EP (1) EP0003937B1 (de)
JP (1) JPS54125959A (de)
DE (1) DE2960025D1 (de)
FR (1) FR2418964A1 (de)

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2520553A1 (fr) * 1982-01-22 1983-07-29 Cameca Appareil d'optique electronique comportant des elements en graphite pyrolytique
US4673842A (en) * 1985-09-03 1987-06-16 General Electric Company Graphite cathode cup for gridded x-ray tubes
US5015908A (en) * 1989-01-23 1991-05-14 Varian Associates, Inc. Fast warm-up cathode for high power vacuum tubes
US5480527A (en) * 1994-04-25 1996-01-02 Vapor Technologies, Inc. Rectangular vacuum-arc plasma source
CN103094019A (zh) * 2013-01-21 2013-05-08 江苏达胜加速器制造有限公司 用于微电流电子枪的灯丝

Family Cites Families (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2498775A (en) * 1948-01-16 1950-02-28 Westinghouse Electric Corp Cathode construction
FR1514813A (fr) * 1967-03-17 1968-02-23 Lokomotivbau Elektrotech Dispositif cathodique à cathode massive à grande surface en hexaborure de lanthanepour générateur de rayons électroniques
US3440475A (en) * 1967-04-11 1969-04-22 Lokomotivbau Elektrotech Lanthanum hexaboride cathode system for an electron beam generator
US3532923A (en) * 1969-03-17 1970-10-06 Ibm Pyrolytic graphite support for lanthanum hexaboride cathode emitter
DE2008176A1 (de) * 1970-02-21 1971-09-09 Fernseh Gmbh Halterung fur die indirekt beheizte Kathode eines Kathodenstrahlsystems
FR2106968A5 (de) * 1970-09-30 1972-05-05 Cit Alcatel
US3958146A (en) * 1974-02-08 1976-05-18 Gte Sylvania Incorporated Fast warm up picture tube cathode cap having high heat emissivity surface on the interior thereof
JPS5277661A (en) * 1975-12-24 1977-06-30 Jeol Ltd Electron gun

Also Published As

Publication number Publication date
EP0003937A3 (en) 1979-09-19
FR2418964A1 (fr) 1979-09-28
EP0003937B1 (de) 1980-10-15
FR2418964B1 (de) 1980-09-05
DE2960025D1 (en) 1981-01-22
JPS54125959A (en) 1979-09-29
US4220889A (en) 1980-09-02

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