EP0028954A1 - Cathode thermo-ionique, son procédé de fabrication et tube électronique incorporant une telle cathode - Google Patents

Cathode thermo-ionique, son procédé de fabrication et tube électronique incorporant une telle cathode Download PDF

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Publication number
EP0028954A1
EP0028954A1 EP80401501A EP80401501A EP0028954A1 EP 0028954 A1 EP0028954 A1 EP 0028954A1 EP 80401501 A EP80401501 A EP 80401501A EP 80401501 A EP80401501 A EP 80401501A EP 0028954 A1 EP0028954 A1 EP 0028954A1
Authority
EP
European Patent Office
Prior art keywords
cathode
matrix
mixture
output work
high output
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.)
Ceased
Application number
EP80401501A
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German (de)
English (en)
French (fr)
Inventor
Arvind Shroff
Pierre Palluel
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 EP0028954A1 publication Critical patent/EP0028954A1/fr
Ceased legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J9/00—Apparatus or processes specially adapted for the manufacture, installation, removal, maintenance of electric discharge tubes, discharge lamps, or parts thereof; Recovery of material from discharge tubes or lamps
    • H01J9/02—Manufacture of electrodes or electrode systems
    • H01J9/04—Manufacture of electrodes or electrode systems of thermionic cathodes
    • 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
    • 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 thermionic cathode and its manufacturing process.
  • 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 invention also relates to such electronic tubes.
  • the power developed by electronic tubes at very high frequencies is limited in particular by the current density produced by the cathode.
  • Thermionic cathodes have long been made up of a tungsten matrix impregnated with barium aluminate and calcium, in varying proportions.
  • the performance of these cathodes is of the order of 1 to 3 A / cm 2, depending on the aluminate compositions used and for temperatures between 1000 and 1035 ° C.
  • Various solutions have been proposed in the prior art in order to improve the performance of these cathodes. Among these solutions, one consists in depositing on the surface a refractory metal with high output work such as iridium, osmium, ruthenium, rhenium. The gain in current density for the same temperature is about a factor of 3.
  • the temperature gain for the same current density is of the order of 80 ° C.
  • a more recent solution no longer consists in depositing on the surface of the cathode a film of refractory metal with high output work, but in mixing with tungsten powder this said metal in variable proportions ranging from a few 10% to 80%, and then impregnate the cathode.
  • the electronic emission characteristics of these cathodes are, depending on the metal used in the mixture, from 2 to 5 times better than those of tungsten cathodes alone.
  • the performance of such a cathode ⁇ reaches 10 to 20 A / cm2 at a temperature between 1300 and 1350 K.
  • Figure 1 represents a network of curves giving the work output ⁇ in eV as a function of the operating temperature T K for the different types of cathodes of the prior art.
  • Curve 1 relates to a cathode consisting of a tungsten matrix and impregnated with a barium and calcium aluminate.
  • Curves 2 and 3 relate to cathodes consisting of a tungsten matrix, impregnated with a barium and calcium aluminate and covered with a film of a refractory metal with high output work such as iridium (curve 2 ), osmium (curve 3) ruthenium or rhenium (curves not shown).
  • Curve 4 relates to a cathode consisting of a mixed matrix composed of a mixture of tungsten powders and a refractory metal with high output work like one of those mentioned above and impregnated with a barium compound .
  • the barium recombines with the underlying aluminate to give a stable product and therefore the recovery is no longer optimal.
  • curve 4 (case of mixed impregnated cathodes) it presents the same variations as those of curve 1 (case of simple impregnated cathodes) but the minimum of the curve is lower.
  • the electronic emission characteristics of these cathodes are, depending on the metal used in the mixture, from 2 to 5 times better than those of simple impregnated cathodes.
  • the gain in temperature, for the same current density, is of the order of 80 ° C as shown by the intersections of the curves (1) (2) (3) (4) with the lines (a) (b ) (c) at constant current density:
  • FIG. 2 represents the curve giving the output work in eV as a function of the operating temperature T K for a cathode according to the invention, that is to say a cathode constituted by a matrix impregnated with a barium compound and made of a powder mixture of two metals, tungsten and another refractory metal with high output work such as osmium, iridium, ruthenium, rhenium, and covered with a film of an ides metals cited above.
  • the curve obtained has a minimum lower than that of the curves in Figure 1.
  • This curve is flat at temperatures below the optimal temperature.
  • a cathode made up of a matrix (W + x) in respective proportions of between 30% and 70%, x being a refractory metal with high output work among those mentioned above, and covered with a film x of thickness included between 5000 A and 10,000 ⁇ , we arrive at performance between 10 and 20 A / cm2 at a temperature between 1300 and 1350 K.
  • FIG. 3 gives an example seen diagrammatically in section of a cathode according to the invention, although in such a figure cannot appear the fact that the matrix 1 consists of a mixture of two powders, namely tungsten and another refractory metal with high output work. We will admit that the part covered with points represented by the index 2 is composed of such a mixture. This matrix 1 is covered with a film 3 of a refractory metal with high output work.
  • this film is approximately 10,000A and that the scale is not respected in the figure.
  • this matrix 1 is also incorporated a filament 4 comprising an insulating film 5.
  • tungsten powder and another refractory metal with high output work having a fairly similar particle size distribution, are mixed without binder, for equal weight.
  • the mixture thus obtained is pressed between 7 and 10 tonnes per cm2 and then pre-sintered under hydrogen at a gloss temperature between 1100 ° C B and 1300 ° C B for about 12 hours.
  • the samples thus obtained are sintered under vacuum at a gloss temperature of between 1850 and 1900 ° C. B. They are then impregnated with barium aluminates and calcium. The excess aluminate present on the surface is eliminated chemically by dissolution in a mineral or organic acid. The thin film is then deposited by sputtering or by evaporation.

Landscapes

  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Solid Thermionic Cathode (AREA)
  • Manufacture Of Alloys Or Alloy Compounds (AREA)
  • Microwave Tubes (AREA)
EP80401501A 1979-11-09 1980-10-22 Cathode thermo-ionique, son procédé de fabrication et tube électronique incorporant une telle cathode Ceased EP0028954A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR7927715 1979-11-09
FR7927715A FR2469792A1 (fr) 1979-11-09 1979-11-09 Cathode thermo-ionique, son procede de fabrication et tube electronique incorporant une telle cathode

Publications (1)

Publication Number Publication Date
EP0028954A1 true EP0028954A1 (fr) 1981-05-20

Family

ID=9231518

Family Applications (1)

Application Number Title Priority Date Filing Date
EP80401501A Ceased EP0028954A1 (fr) 1979-11-09 1980-10-22 Cathode thermo-ionique, son procédé de fabrication et tube électronique incorporant une telle cathode

Country Status (4)

Country Link
US (1) US4393328A (OSRAM)
EP (1) EP0028954A1 (OSRAM)
JP (1) JPS5679830A (OSRAM)
FR (1) FR2469792A1 (OSRAM)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3125915A1 (de) * 1981-07-01 1983-01-20 Licentia Patent-Verwaltungs-Gmbh, 6000 Frankfurt Verfahren zum herstellen einer vorratskathode und vorrichtung zur durchfuehrung des verfahrens
FR2515869A1 (fr) * 1981-10-29 1983-05-06 Varian Associates Tube electronique et cathode a impregnation a emission elevee
EP0157634A3 (en) * 1984-04-02 1986-01-08 Varian Associates, Inc. Tungsten-iridium impregnated cathode
EP0441698A1 (fr) * 1990-02-09 1991-08-14 Thomson Tubes Electroniques Procédé de fabrication d'une cathode imprégnée, et cathode obtenue par ce procédé

Families Citing this family (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2050045A (en) * 1979-05-29 1980-12-31 Emi Varian Ltd Thermionic cathode
JPS56102036A (en) * 1980-01-17 1981-08-15 New Japan Radio Co Ltd Manufacture of thermionic emission type cathode
DE3467467D1 (en) * 1983-09-30 1987-12-17 Bbc Brown Boveri & Cie Thermionic cathode capable of high emission for an electron tube, and method of manufacture
US5266414A (en) * 1988-03-18 1993-11-30 Varian Associates, Inc. Solid solution matrix cathode
DE3913338C2 (de) * 1989-04-22 1999-12-02 Aeg Elektronische Roehren Gmbh Einbettmasse, insbesondere für Kathoden von Elektronenröhren, Verfahren zur Herstellung einer solchen Einbettmasse und Verwendung einer solchen Einbettmasse
RU2683243C1 (ru) * 2017-10-03 2019-03-27 Анатолий Степанович Плахотник Магнетрон с тонким катодом
CN109065420A (zh) * 2018-08-09 2018-12-21 中国电子科技集团公司第十二研究所 一种具有三维结构表面的热阴极及其制备方法

Citations (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR1497992A (fr) * 1966-10-28 1967-10-13 Philips Nv Dispositif équipé d'une diode fonctionnant dans la zone de naissance du courant et diode destinée à un tel dispositif
NL6701867A (OSRAM) * 1967-02-08 1968-08-09
FR1555031A (OSRAM) * 1967-02-08 1969-01-24
NL6800278A (OSRAM) * 1968-01-09 1969-07-11
NL6917538A (OSRAM) * 1969-11-21 1971-05-25
FR2063018A1 (OSRAM) * 1968-09-26 1971-07-02 Gen Electric
DE2727187A1 (de) * 1976-06-21 1977-12-29 Varian Associates Mikrowellen-elektronenroehre, gluehkathode fuer diese und verfahren zu deren herstellung
SU614475A1 (ru) * 1976-08-09 1978-07-05 Предприятие П/Я М-5174 Катод с запасом активного вещества
DE2720553A1 (de) * 1977-05-07 1978-11-09 Licentia Gmbh Verfahren zum herstellen eines vorratskoerpers fuer eine vorratskathode
EP0004424A1 (en) * 1978-03-23 1979-10-03 Thorn Emi-Varian Limited Thermionic cathode
EP0019992A1 (en) * 1979-05-29 1980-12-10 Thorn Emi-Varian Limited Thermionic electron emitters and methods of making them

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2581408A (en) * 1947-04-16 1952-01-08 Sperry Corp High-frequency electron discharge device
BE550302A (OSRAM) * 1955-08-15
BE560502A (OSRAM) * 1956-09-05
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
US4101800A (en) * 1977-07-06 1978-07-18 The United States Of America As Represented By The Secretary Of The Navy Controlled-porosity dispenser cathode

Patent Citations (16)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR1497992A (fr) * 1966-10-28 1967-10-13 Philips Nv Dispositif équipé d'une diode fonctionnant dans la zone de naissance du courant et diode destinée à un tel dispositif
NL6701867A (OSRAM) * 1967-02-08 1968-08-09
FR1555031A (OSRAM) * 1967-02-08 1969-01-24
GB1164413A (en) * 1967-02-08 1969-09-17 Philips Electronic Associated Cathode Assembly
DE1639344A1 (de) * 1967-02-08 1971-02-04 Philips Nv Elektrische Entladungsroehre mit einer Kathode,deren Inneres ein Aktivierungsmaterial enthaelt,und Kathode zur Anwendung in einer derartigen Entladungsroehre
NL6800278A (OSRAM) * 1968-01-09 1969-07-11
FR2063018A1 (OSRAM) * 1968-09-26 1971-07-02 Gen Electric
FR2069601A5 (OSRAM) * 1969-11-21 1971-09-03 Philips Nv
NL6917538A (OSRAM) * 1969-11-21 1971-05-25
DE2054698A1 (de) * 1969-11-21 1971-11-18 Philips Nv Verfahren zur Herstellung einer Vorratskathode und durch dieses Verfahren hergestellte Kathode
GB1264087A (OSRAM) * 1969-11-21 1972-02-16
DE2727187A1 (de) * 1976-06-21 1977-12-29 Varian Associates Mikrowellen-elektronenroehre, gluehkathode fuer diese und verfahren zu deren herstellung
SU614475A1 (ru) * 1976-08-09 1978-07-05 Предприятие П/Я М-5174 Катод с запасом активного вещества
DE2720553A1 (de) * 1977-05-07 1978-11-09 Licentia Gmbh Verfahren zum herstellen eines vorratskoerpers fuer eine vorratskathode
EP0004424A1 (en) * 1978-03-23 1979-10-03 Thorn Emi-Varian Limited Thermionic cathode
EP0019992A1 (en) * 1979-05-29 1980-12-10 Thorn Emi-Varian Limited Thermionic electron emitters and methods of making them

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
SOVIET INVENTIONS ILLUSTRATED Vol. B20, Section R: Electrical, 27 Juin 1979 page SU-R4 (R45) & SU-A-614 475 (9 Aout 1976) * resume en entier * *

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3125915A1 (de) * 1981-07-01 1983-01-20 Licentia Patent-Verwaltungs-Gmbh, 6000 Frankfurt Verfahren zum herstellen einer vorratskathode und vorrichtung zur durchfuehrung des verfahrens
FR2515869A1 (fr) * 1981-10-29 1983-05-06 Varian Associates Tube electronique et cathode a impregnation a emission elevee
EP0157634A3 (en) * 1984-04-02 1986-01-08 Varian Associates, Inc. Tungsten-iridium impregnated cathode
EP0441698A1 (fr) * 1990-02-09 1991-08-14 Thomson Tubes Electroniques Procédé de fabrication d'une cathode imprégnée, et cathode obtenue par ce procédé
FR2658360A1 (fr) * 1990-02-09 1991-08-16 Thomson Tubes Electroniques Procede de fabrication d'une cathode impregnee et cathode obtenue par ce procede.
US5334085A (en) * 1990-02-09 1994-08-02 Thomson Tubes Electroniques Process for the manufacture of an impregnated cathode and a cathode obtained by this process

Also Published As

Publication number Publication date
JPS5679830A (en) 1981-06-30
US4393328A (en) 1983-07-12
FR2469792B1 (OSRAM) 1982-10-01
FR2469792A1 (fr) 1981-05-22

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PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

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Inventor name: SHROFF, ARVIND

Inventor name: PALLUEL, PIERRE