US3532923A - Pyrolytic graphite support for lanthanum hexaboride cathode emitter - Google Patents

Pyrolytic graphite support for lanthanum hexaboride cathode emitter Download PDF

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Publication number
US3532923A
US3532923A US807695A US3532923DA US3532923A US 3532923 A US3532923 A US 3532923A US 807695 A US807695 A US 807695A US 3532923D A US3532923D A US 3532923DA US 3532923 A US3532923 A US 3532923A
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United States
Prior art keywords
tip
pyrolytic graphite
emitter
lanthanum hexaboride
cathode
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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 - Lifetime
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US807695A
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English (en)
Inventor
Siegfried F Vogel
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International Business Machines Corp
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International Business Machines Corp
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Publication date
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    • 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
    • H01J1/14—Solid thermionic cathodes characterised by the material
    • H01J1/148—Solid thermionic cathodes characterised by the material with compounds having metallic conductive properties, e.g. lanthanum boride, as an emissive material
    • 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

Definitions

  • a thermionic cathode such as one using a lanthanum hexaboride emitter and a support therefor made of pyrolytic graphite material abutting and holding said emitter and through which heating current is passed for raising the temperature of the cathode to cause emission.
  • FIG. 1 shows a cathode structure utilizing a first em bodiment of the subject invention.
  • FIG. 2 is a top view of the emission tip and supporting structure.
  • the invention is to be used in a thermionic emitter such as the cathode structure 10 having a lanthanum hexaboride emitter tip 11 for use in electron beam devices.
  • Emission occurring when the tip is heated, passes through an opening 12 in a Wehnelt cylinder 13 mounted on the cathode structure.
  • the cylinder is held in position by a pair of locking rings 15 and 16 threaded to the inside of the cylinder and clamping therebetween a ring 17 fixed to a ceramic insulator 18.
  • the thermionic emitting tip is held by a pyrolytic graphite member which serves both as the mechanical support and the heater for the emitting tip.
  • a pyrolytic graphite member which serves both as the mechanical support and the heater for the emitting tip.
  • a pair of conductor posts 21 and 22 are extended through the insulator 18 and into the cavity 24 of the Wehnelt electrode such that the extending tips 25 and 26 clamp a pair of pyrolytic grapite members 19 and 20 against the emitter tip.
  • the tip is held at a position in alignment with the opening 12.
  • the post 21 is formed with a body member 27 extending parallel to the tip 25 such that a screw 28 threaded therein will exert lateral pressure on the tip in a direction towards the other tip 26 as shown in FIG. 2 thereby serving as a clamping means for said cathode.
  • the pressure on the electrode tip is lessened to permit its removal and replacement in the cathode structure.
  • Spring members not shown, can be substituted for supplying the clamping pressure in the manner similar to the screw 28.
  • the lanthanum hexaboride and emitter tip can be brazed together before assembly into the cathode assembly if desired.
  • an electric current is passed into one of the posts 21 or 22 for conduction through the series circuit comprising the pyrolytic graphite members 19 and 20 and the emitter tip 11, and thereafter out the other post.
  • the emitter tip is heated by the resistivity of the pyrolytic graphite members to raise the temperature of the emitter tip above that necessary for the desired electron emission.
  • the pyrolytic graphite is well-adapted as a heater since in one direction of material alignment it has a high electrical resistance with a high ratio of electrical resistivity to heat conductivity thereby serving not only to supply the heat to the emitter tip but also to isolate the high temperature area from that of the supporting posts 21 and 22.
  • the pyrolytic graphite is formed in a layered structure with the preferable cathode assembly of the subject invention having these layers extending perpendicular to the direction of current flow between the sup porting posts 21 and 22.
  • the lathe structure tends to oppose the conduction of heat from the emitter tip while serving to raise the electrical resistivity of the members 19 and 20.
  • the pyrolytic graphite material is uniquely suited for use as a support member for thermionic emitters, and in particular those utilizing lanthanum hexaboride as the emitter material.
  • a thermionic cathode comprising:
  • an emitter tip made of a material capable of electron emission when heated
  • a support for said emitter made of a pyrolytic graphic material in heat transfer relationship with said emitter tip such that with the passage of electric current therethrough, said support will become heated and transmit heat to said tip to cause emission therefrom.
  • a thermionic cathode as defined in claim 4 including means to exert a clamping pressure on said pyrolytic graphite members thereby holding said cathode structure together.
  • a thermionic cathode as defined in claim 6 including a Wehnelt cylinder fixed to said clamping means and extending around said cathode.

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  • Solid Thermionic Cathode (AREA)
  • Electron Sources, Ion Sources (AREA)
US807695A 1969-03-17 1969-03-17 Pyrolytic graphite support for lanthanum hexaboride cathode emitter Expired - Lifetime US3532923A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US80769569A 1969-03-17 1969-03-17

Publications (1)

Publication Number Publication Date
US3532923A true US3532923A (en) 1970-10-06

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Family Applications (1)

Application Number Title Priority Date Filing Date
US807695A Expired - Lifetime US3532923A (en) 1969-03-17 1969-03-17 Pyrolytic graphite support for lanthanum hexaboride cathode emitter

Country Status (4)

Country Link
US (1) US3532923A (enrdf_load_stackoverflow)
DE (1) DE2011615C3 (enrdf_load_stackoverflow)
FR (1) FR2033868A5 (enrdf_load_stackoverflow)
GB (1) GB1284034A (enrdf_load_stackoverflow)

Cited By (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3711908A (en) * 1970-08-27 1973-01-23 Ibm Method for forming small diameter tips on sintered material cathodes
US3728570A (en) * 1968-07-07 1973-04-17 Department Of Eng University O Electron probe forming system
US3866077A (en) * 1971-07-09 1975-02-11 Nat Res Dev Electron emitters
US4068145A (en) * 1975-12-24 1978-01-10 Nihon Denshi Kabushiki Kaisha Insulated elastic support and clamping means for resistance heaters and emitter tip of electron gun
DE2832027A1 (de) * 1977-09-02 1979-03-15 Balzers Hochvakuum Kathode fuer elektronenmission
US4193013A (en) * 1977-04-18 1980-03-11 Hitachi, Ltd. Cathode for an electron source and a method of producing the same
DE3001622A1 (de) * 1979-01-23 1980-07-24 Denki Kagaku Kogyo Kk Tragvorrichtung fuer eine gluehkathode
US4220889A (en) * 1978-03-01 1980-09-02 Commissariat A L'energie Atomique Cathode for an electron gun
US4258283A (en) * 1978-08-31 1981-03-24 Balzers Aktiengesellschaft Fur Hochvakuumtechnik Und Dunne Schichten Cathode for electron emission
US4288717A (en) * 1979-11-06 1981-09-08 Denki Kagaku Kogyo Kabushiki Kaisha Thermionic cathode apparatus
US4760306A (en) * 1983-06-10 1988-07-26 The United States Of America As Represented By The United States Department Of Energy Electron emitting filaments for electron discharge devices
US5001385A (en) * 1988-03-03 1991-03-19 U.S. Philips Corp. Electron beam apparatus with adjusting mechanism for a thermally emitting cathod tip
US20100301736A1 (en) * 2007-11-30 2010-12-02 Toshiyuki Morishita Electron emitting source and manufacturing method of electron emitting source

Families Citing this family (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2732960C2 (de) * 1977-07-21 1982-04-01 Philips Patentverwaltung Gmbh, 2000 Hamburg Glühkathode und Verfahren zu ihrer Herstellung
DE2838020C3 (de) * 1978-08-31 1987-06-19 Siemens AG, 1000 Berlin und 8000 München Direkt geheizte Kathode für Senderöhren mit koaxialem Aufbau der Elektroden
JPS6023456B2 (ja) * 1978-11-01 1985-06-07 電気化学工業株式会社 熱電子陰極装置
FR2445605A1 (fr) * 1978-12-27 1980-07-25 Thomson Csf Cathode a chauffage direct et tube electronique haute frequence comportant une telle cathode
US5444327A (en) * 1993-06-30 1995-08-22 Varian Associates, Inc. Anisotropic pyrolytic graphite heater
FR2726121B1 (fr) * 1994-10-21 1996-11-15 Thomson Tubes Electroniques Dispositif de chauffage par rayonnement pour cathode a chauffage indirect

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US323983A (en) * 1885-08-11 Incandescent lamp
US978094A (en) * 1909-09-13 1910-12-06 Frederick R Campbell Incandescent electric lamp.
US2813991A (en) * 1952-11-05 1957-11-19 Gen Electric Electron emitting electrode
US3069584A (en) * 1959-07-29 1962-12-18 Jack W Frazer Method of making tungsten filaments
US3374386A (en) * 1964-11-02 1968-03-19 Field Emission Corp Field emission cathode having tungsten miller indices 100 plane coated with zirconium, hafnium or magnesium on oxygen binder

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US323983A (en) * 1885-08-11 Incandescent lamp
US978094A (en) * 1909-09-13 1910-12-06 Frederick R Campbell Incandescent electric lamp.
US2813991A (en) * 1952-11-05 1957-11-19 Gen Electric Electron emitting electrode
US3069584A (en) * 1959-07-29 1962-12-18 Jack W Frazer Method of making tungsten filaments
US3374386A (en) * 1964-11-02 1968-03-19 Field Emission Corp Field emission cathode having tungsten miller indices 100 plane coated with zirconium, hafnium or magnesium on oxygen binder

Cited By (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3728570A (en) * 1968-07-07 1973-04-17 Department Of Eng University O Electron probe forming system
US3711908A (en) * 1970-08-27 1973-01-23 Ibm Method for forming small diameter tips on sintered material cathodes
US3866077A (en) * 1971-07-09 1975-02-11 Nat Res Dev Electron emitters
US4068145A (en) * 1975-12-24 1978-01-10 Nihon Denshi Kabushiki Kaisha Insulated elastic support and clamping means for resistance heaters and emitter tip of electron gun
US4193013A (en) * 1977-04-18 1980-03-11 Hitachi, Ltd. Cathode for an electron source and a method of producing the same
DE2832027A1 (de) * 1977-09-02 1979-03-15 Balzers Hochvakuum Kathode fuer elektronenmission
US4220889A (en) * 1978-03-01 1980-09-02 Commissariat A L'energie Atomique Cathode for an electron gun
US4258283A (en) * 1978-08-31 1981-03-24 Balzers Aktiengesellschaft Fur Hochvakuumtechnik Und Dunne Schichten Cathode for electron emission
DE3001622A1 (de) * 1979-01-23 1980-07-24 Denki Kagaku Kogyo Kk Tragvorrichtung fuer eine gluehkathode
US4288717A (en) * 1979-11-06 1981-09-08 Denki Kagaku Kogyo Kabushiki Kaisha Thermionic cathode apparatus
US4760306A (en) * 1983-06-10 1988-07-26 The United States Of America As Represented By The United States Department Of Energy Electron emitting filaments for electron discharge devices
US5001385A (en) * 1988-03-03 1991-03-19 U.S. Philips Corp. Electron beam apparatus with adjusting mechanism for a thermally emitting cathod tip
US20100301736A1 (en) * 2007-11-30 2010-12-02 Toshiyuki Morishita Electron emitting source and manufacturing method of electron emitting source
US8456076B2 (en) 2007-11-30 2013-06-04 Denki Kagaku Kogyo Kabushiki Kaisha Electron emitting source and manufacturing method of electron emitting source

Also Published As

Publication number Publication date
GB1284034A (en) 1972-08-02
FR2033868A5 (enrdf_load_stackoverflow) 1970-12-04
DE2011615A1 (de) 1970-09-24
DE2011615B2 (de) 1973-05-10
DE2011615C3 (de) 1973-12-06

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