EP0052047B1 - Thermoelektronische Kathode - Google Patents

Thermoelektronische Kathode Download PDF

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Publication number
EP0052047B1
EP0052047B1 EP81401713A EP81401713A EP0052047B1 EP 0052047 B1 EP0052047 B1 EP 0052047B1 EP 81401713 A EP81401713 A EP 81401713A EP 81401713 A EP81401713 A EP 81401713A EP 0052047 B1 EP0052047 B1 EP 0052047B1
Authority
EP
European Patent Office
Prior art keywords
porous body
impregnated
barium
cathode according
thermoelectronic
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
EP81401713A
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English (en)
French (fr)
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EP0052047A1 (de
EP0052047B2 (de
Inventor
Pierre Palluel
Arvind Shroff
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Thales SA
Original Assignee
Thomson CSF SA
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Application filed by Thomson CSF SA filed Critical Thomson CSF SA
Publication of EP0052047A1 publication Critical patent/EP0052047A1/de
Publication of EP0052047B1 publication Critical patent/EP0052047B1/de
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Classifications

    • 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
    • H01J1/20—Cathodes heated indirectly by an electric current; Cathodes heated by electron or ion bombardment
    • H01J1/28—Dispenser-type cathodes, e.g. L-cathode
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J23/00—Details of transit-time tubes of the types covered by group H01J25/00
    • H01J23/02—Electrodes; Magnetic control means; Screens
    • H01J23/04—Cathodes

Definitions

  • the present invention relates to a new thermoelectronic cathode structure.
  • Such cathodes find their field of application in electronic tubes, tubes with localized constants such as triodes and tetrodes, or tubes with distributed constants such as klystrons and magnetrons used at microwave frequencies.
  • the power developed by electronic tubes at very high frequencies is limited in particular by the current density produced by the cathode.
  • Thermoelectronic cathodes with a reserve of emissive material have been known for a long time under the name of "L " cathodes;
  • Another improvement consisted in replacing the reserve of alkaline earth with a ceramic consisting of a mixture of alumina, alkaline earth oxides and tungsten powder.
  • impregnated cathodes constituted by a tungsten matrix impregnated with barium and calcium aluminates, in variable proportions.
  • impregnated cathode is described, for example, in DE-A-2 808 134.
  • the cathode described in this application is constituted by a porous accumulator body comprising at least two layers in the pores of which an emissive material is stored, the two layers which may have identical or different porosities. Since the emissive material is impregnated in the two layers, this cathode functions like an impregnated cathode constituted by a matrix in a single layer.
  • L type cathodes have always exhibited a density of emitted current, at equal temperature, greater than that of so-called impregnated cathodes, even in the best cases when the latter are covered with '' a film of a refractory metal with high output work such as osmium, ruthenium, iridium, rhenium, which tends to increase the current density.
  • thermoelectronic cathode comprising inside a cylindrical envelope, a heating filament located in the lower part of said envelope, and two superposed porous bodies inserted at the top of the envelope.
  • the porous bodies are produced by a mixture comprising by weight 90% of powdered tungsten and 10% of barium carbonate or barium peroxide and carbon, mixture covered with a layer of powdered tungsten sintered during activation. It is therefore not a porous body of the impregnated type and the technique for producing this type of cathode is very complex when it is desired to have doses of known volume and weight.
  • the Applicant proposes to produce a cathode structure whose current density is at least equal to that of “L” cathodes, but which would not present the difficulties of technological realization of the latter, or of other types. of cathodes described above.
  • thermo-electronic cathode comprising, inside a cylindrical envelope, a heating filament situated in the lower part of said envelope, and two superposed porous bodies, inserted in the upper part of the envelope, both porous body being constituted by a lower body containing an emissive material, covered with the upper body, the surface of the upper porous body forming the emissive surface of the cathode, characterized in that the lower porous body is a porous body of porosity between 16 and 50% impregnated with the emissive material and the upper porous body is a non-impregnated porous body with porosity between 16 and 21%.
  • FIG. 1 represents an example of a cathode structure “L” of the prior art.
  • a cathode is constituted by a molybdenum tube 1, divided into two cavities; the lower part contains the heating filament 2; the upper part consists of a chamber 3 containing a reserve 4 of barium and calcium carbonates for example.
  • a porous tungsten disc 5 is attached to the top of the barium reservoir, so that the upper cavity communicates outward only through the porous body.
  • the upper face of this disc may comprise a thin layer 6 of a refractory metal with high output work such as osmium, iridium, rhenium, ruthenium, or an alloy of several of these materials.
  • a refractory metal with high output work such as osmium, iridium, rhenium, ruthenium, or an alloy of several of these materials.
  • FIG. 2 represents an example of a cathode structure impregnated with the prior art.
  • a filament 2 is located inside a molybdenum cylinder 1 containing a body of porous tungsten 7 which is impregnated with barium and calcium aluminates.
  • the upper face of the body 7 can be covered with a thin layer 6 of a refractory metal with high output work from one of those mentioned above.
  • the underside of the body 7 rests on a molybdenum bottom 8 ensuring sealing.
  • FIG. 3 represents an example of a cathode structure according to the invention.
  • the cathode according to the invention consists of a cylindrical molybdenum body 1 inside which is located a filament 2 in its lower part and a set of two porous bodies superimposed in its upper part: a porous body 9 free of all impregnating, with a porosity of between 16 and 21%, made of tungsten or of a tungsten alloy and of a refractory metal with high output work such as iridium, rhenium, osmium, ruthenium, porous body of which the front face 10 is the only one through which the emissive material can escape, and a porous body 12 in contact with the rear face 11 of the porous body 9 impregnated with barium and calcium aluminates or a mixture comprising barium aluminates, of calcium and a scandium or barium scandate oxide, this porous body having a porosity of between 16 and 50%, for example.
  • the rear face of the porous body 12 is sealed by conventional means such as the deposition of molyb
  • the front face 10 of the non-impregnated porous body 9 can be covered with a layer of refractory metal with high output work.
  • the porous impregnated body can consist of tungsten impregnated with barium and calcium aluminates, an alloy of tungsten and a refractory metal with high output work impregnated with barium aluminates and calcium or tungsten impregnated with a mixture of barium aluminates and calcium and a scandium oxide.
  • a gap or gap 14 which is filled, in order to improve the thermal contact before placing the porous body 3, either of powder of a conductive metal at high melting temperature, or a grid of molybdenum or tungsten, with a very fine mesh, of pitch 20 ⁇ m for example, which serves as additional conductance for the diffusion of barium towards the porous body 9, or of a flexible foil ensuring contact between the bodies cathodes, either using a thread.
  • This gap 14 can be eliminated by making the assembly by pressing.
  • the porous body 9 generally has a curved shape obtained by machining or by pressing.
  • the operating mechanism of this type of cathode is as follows: the free barium is produced in the porous body 12 by heating the assembly using the filament 2, by chemical reaction between the impregnating agent and the tungsten.
  • This barium then migrates through the pores of the body 3 from the face 11 to the face 10 where it covers its surface, thus lowering the work of leaving it.
  • An electrode placed opposite the cathode, at a certain distance, and brought to a positive potential with respect to the cathode, collects the electrons emitted by the latter.

Landscapes

  • Solid Thermionic Cathode (AREA)
  • Microwave Tubes (AREA)

Claims (8)

1. Thermoelektronische Kathode mit einem Heizfaden (2) im Inneren einer zylindrischen Hülle (1), und zwar im unteren Teil dieser Hülle, und mit zwei übereinanderliegenden porösen Körpern im oberen Teil der Hülle, nämlich einem unten liegenden Körper (12), der ein emittierendes Material enthält, und einem oberen Körper (9), wobei die Oberfläche des oben liegenden porösen Körpers die emittierende Oberfläche der Kathode bildet, dadurch gekennzeichnet, dass der unten liegende poröse Körper ein poröser Körper einer Porosität ist, die zwischen 16 und 50% liegt, wobei dieser Körper mit dem emittierenden Material imprägniert ist, und dass der oben liegende poröse Körper ein nicht imprägnierter poröser Körper ist, dessen Porosität zwischen 16 und 21% liegt.
2. Thermoelektronische Kathode nach Anspruch 1, dadurch gekennzeichnet, dass zwischen dem imprägnierten porösen Körper (12) und dem nicht imprägnierten porösen Körper (9) ein leitendes Metallpulver mit hoher Schmelztemperatur vorgesehen ist.
3. Thermoelektronische Kathode nach Anspruch 1, dadurch gekennzeichnet, dass ein feinmaschiges Gitter aus Molybdän oder Wolfram zwischen dem imprägnierten porösen Körper (12) und dem nicht imprägnierten porösen Körper (9) vorgesehen ist.
4. Thermoelektronische Kathode nach Anspruch 1, dadurch gekennzeichnet, dass eine weiche Schicht aus Flittermetall zwischen dem imprägnierten porösen Körper (12) und dem nicht imprägnierten porösen Körper (9) vorgesehen ist.
5. Thermoelektronische Kathode nach einem beliebigen der Ansprüche 1 bis 4, dadurch gekennzeichnet, dass der imprägnierte poröse Körper mit einer Mischung aus Barium- und Calciumaluminaten und aus einem Scandiumoxid imprägniert ist.
6. Thermoelektronische Kathode nach einem beliebigen der Ansprüche 1 bis 4, dadurch gekennzeichnet, dass der imprägnierte poröse Körper mit einer Mischung aus Barium- und Calciumaluminaten und aus Bariumscandat imprägniert ist.
7. Thermoelektronische Kathode nach einem beliebigen der Ansprüche 1 bis 6, dadurch gekennzeichnet, dass der poröse nicht imprägnierte Körper (9) von einer Wolframschicht (15) bedeckt ist, die tiefliegende und reliefartig vorstehende Bereiche aufweist.
8. Thermoelektronische Kathode nach Anspruch 7, dadurch gekennzeichnet, dass die reliefartig vorstehenden Bereiche mit einem temperaturfesten Material (16) mit grosser Austrittsarbeit bedeckt sind.
EP81401713A 1980-11-07 1981-10-27 Thermoelektronische Kathode Expired - Lifetime EP0052047B2 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR8023884A FR2494035A1 (fr) 1980-11-07 1980-11-07 Cathode thermo-electronique pour tube hyperfrequences et tube incorporant une telle cathode
FR8023884 1980-11-07

Publications (3)

Publication Number Publication Date
EP0052047A1 EP0052047A1 (de) 1982-05-19
EP0052047B1 true EP0052047B1 (de) 1986-01-08
EP0052047B2 EP0052047B2 (de) 1990-05-02

Family

ID=9247818

Family Applications (1)

Application Number Title Priority Date Filing Date
EP81401713A Expired - Lifetime EP0052047B2 (de) 1980-11-07 1981-10-27 Thermoelektronische Kathode

Country Status (5)

Country Link
US (1) US4494035A (de)
EP (1) EP0052047B2 (de)
JP (1) JPS57107534A (de)
DE (1) DE3173470D1 (de)
FR (1) FR2494035A1 (de)

Families Citing this family (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0719530B2 (ja) * 1984-06-29 1995-03-06 株式会社日立製作所 陰極線管
JPH0416344Y2 (de) * 1985-07-02 1992-04-13
FR2596198A1 (fr) * 1986-03-19 1987-09-25 Thomson Csf Cathodes pour klystron a faisceaux multiples, klystron comportant de telles cathodes et procede de fabrication de telles cathodes
JPS63236239A (ja) * 1987-03-10 1988-10-03 シーメンス、アクチエンゲゼルシヤフト 放電管用デイスペンサー陰極とその製法
US4810926A (en) * 1987-07-13 1989-03-07 Syracuse University Impregnated thermionic cathode
US5266414A (en) * 1988-03-18 1993-11-30 Varian Associates, Inc. Solid solution matrix cathode
FR2647952A1 (fr) * 1989-05-30 1990-12-07 Thomson Tubes Electroniques Cathode thermoelectronique impregnee pour tube electronique
CH678671A5 (de) * 1989-08-22 1991-10-15 Asea Brown Boveri
DE19527723A1 (de) * 1995-07-31 1997-02-06 Philips Patentverwaltung Elektrische Entladungsröhre oder Entladungslampe und Scandat-Vorratskathode
JP3696720B2 (ja) * 1997-07-09 2005-09-21 松下電器産業株式会社 含浸型陰極とその製造方法
JPH11102636A (ja) 1997-09-26 1999-04-13 Matsushita Electron Corp 陰極、陰極の製造方法、受像管
US6495949B1 (en) * 1999-11-03 2002-12-17 Orion Electric Co., Ltd. Electron tube cathode
FR2833406A1 (fr) * 2001-12-10 2003-06-13 Thomson Licensing Sa Cathode pour tube a vide a duree de vie amelioree
CN103311066B (zh) * 2013-06-03 2015-08-19 哈尔滨工业大学 具有内芯的用于航天器自持空心阴极的发射体
CN116387116B (zh) * 2023-03-29 2025-05-30 中国科学院空天信息创新研究院 浸渍型阴极及其制备方法

Family Cites Families (16)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR1093241A (de) * 1953-02-16 1955-05-02
NL208455A (de) * 1954-06-29
NL94233C (de) * 1954-12-06
US3076915A (en) * 1954-12-24 1963-02-05 Egyesuelt Izzolampa Cathode assembly and method of making same
NL272981A (de) * 1961-01-02
US3373307A (en) * 1963-11-21 1968-03-12 Philips Corp Dispenser cathode
US3558966A (en) * 1967-03-01 1971-01-26 Semicon Associates Inc Directly heated dispenser cathode
BE759174A (fr) * 1969-11-21 1971-05-19 Philips Nv Cathode a reserve et son procede de realisation
US3842309A (en) * 1970-11-12 1974-10-15 Philips Corp Method of manufacturing a storage cathode and cathode manufactured by said method
US3719856A (en) * 1971-05-19 1973-03-06 O Koppius Impregnants for dispenser cathodes
DE2245717A1 (de) * 1972-09-18 1974-03-28 Patra Patent Treuhand Elektrode mit einem poroesen sinterkoerper
US4165473A (en) * 1976-06-21 1979-08-21 Varian Associates, Inc. Electron tube with dispenser cathode
FR2390825A1 (fr) * 1977-05-13 1978-12-08 Thomson Csf Cathode thermo-ionique a grille incorporee, son procede de fabrication et tube electronique comportant une telle cathode
DE2808134A1 (de) * 1978-02-25 1979-08-30 Licentia Gmbh Vorratskathode
US4310603A (en) * 1978-11-30 1982-01-12 Varian Associates, Inc. Dispenser cathode
JPS5652835A (en) * 1979-10-01 1981-05-12 Hitachi Ltd Impregnated cathode

Also Published As

Publication number Publication date
FR2494035A1 (fr) 1982-05-14
US4494035A (en) 1985-01-15
FR2494035B1 (de) 1983-05-13
JPS57107534A (en) 1982-07-05
EP0052047A1 (de) 1982-05-19
EP0052047B2 (de) 1990-05-02
DE3173470D1 (en) 1986-02-20

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