EP0038742B1 - Procédé de réalisation d'une cathode imprégnée à grille intégrée, cathode obtenue par ce procédé, et tube électronique muni d'une telle cathode - Google Patents

Procédé de réalisation d'une cathode imprégnée à grille intégrée, cathode obtenue par ce procédé, et tube électronique muni d'une telle cathode Download PDF

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Publication number
EP0038742B1
EP0038742B1 EP81400577A EP81400577A EP0038742B1 EP 0038742 B1 EP0038742 B1 EP 0038742B1 EP 81400577 A EP81400577 A EP 81400577A EP 81400577 A EP81400577 A EP 81400577A EP 0038742 B1 EP0038742 B1 EP 0038742B1
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EP
European Patent Office
Prior art keywords
grid
cathode
reserves
layer
integrated
Prior art date
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Expired
Application number
EP81400577A
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German (de)
English (en)
French (fr)
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EP0038742A1 (fr
Inventor
Didier Grauleau
Arvind Shroff
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
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    • 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

Definitions

  • the invention relates to a method for producing cathodes with integrated grids.
  • cathodes of this kind has been made necessary by the constant rise in the power level of electronic tubes, in particular for microwaves, in which the power of the electron beam has become such that the fraction of it intercepted by the grids placed on its path can be enough to considerably alter their characteristics (dimensions, alignment, mechanical strength ...) and even threaten their life.
  • One of the main problems encountered in this respect is that of the first two grids, usually designated by G, and G 2 ; these grids, ensuring respectively the control and the acceleration of the electron beam emitted by the cathode, must have their bars aligned, the first bringing shade on the second, so as to avoid too great interception of the beam by the latter; with the integration of the first of these grids, G 1 , into the cathode, this condition is more easily achieved; as for the grid G, itself, due to its integration, it is sheltered from such interception.
  • the grid G is engraved on the emissive face of the cathode, on which its solid parts constitute zones withdrawn from the emission surrounding emissive zones, according, for example, to a network of meshes arranged in lines and columns rectangular.
  • the subject of the invention is such a method, applicable to the case of impregnated cathodes, consisting, as is known in the art, of a solid part made of a metal powder with a high sintered melting point, in which is incorporated a powder from an emissive body, usually a barium compound.
  • the method of the invention applies to the formation of the first grid integrated in such a cathode. In one of its variants, it applies to the incorporation into the previous building of the second of the grids of the cathode assemblies, namely the grid G 2 which was discussed above.
  • the invention also covers cathodes manufactured according to this process, as well as the electronic tubes which are provided with them.
  • the invention relates to a method for producing an impregnated cathode with an integrated grid, consisting of a solid piece of sintered metal impregnated with a powder of an electron-emitting material 1 and of a grid 6 incorporated into this cathode on its face 2 emitting electrons in operation, the grid being made of a non-emissive material at the operating temperature of said cathode, said method consisting in forming on face 2 a grid constituted by reserves 5, complementary to the grid to be incorporated into the cathode, to cover the whole face 2, including the complementary grid, of the material of the grid to be incorporated, then to eliminate the material of the complementary grid and the material of grid 5 covering them, and being characterized in that the reserves are made of a volatile metal with a high vapor pressure, and in that the elimination of this metal and of the grid material 5 covering said reserves is effected by volatilization of the latter.
  • a layer 10 (fig. 1b) of the material of the non-emissive grid to be produced, tungsten for example (see the cited patent), then one engraves by photogravure, in the cathode 1, the drawing of the grid whose bars limiting the meshes carry the reference mark 11.
  • FIGS. 2a, b, c the drawing of the grid is machined in the cathode body 1 (fig. 2a), as shown in the drawing of fig. 2b, then the grooves 20 resulting from this machining are filled with non-emissive material forming the bars 21 of the grid.
  • FIGS. 3a to 3f The process of the invention is illustrated in FIGS. 3a to 3f.
  • a volatile material with a high vapor pressure, is used under the conditions which will be specified below.
  • a grid similar to that which one wishes to produce is produced on the emissive face 2 of the cathode; this grid 3 subsequently plays the role of mask; it is made of a refractory metal, such as molybdenum; it can also be made of graphite.
  • a volatile material with high vapor pressure such as magnesium, zinc, cadmium, etc., from a heated crucible 30, according to any suitable technique, vacuum evaporation, for example, inside an enclosure 31; this deposit has a thickness of the order of 20 to 50 ⁇ m .
  • the mask 3 is then removed; there then remains on the face 2 a grid complementary to that to be produced (FIG. 3c), formed of reserves 4, made of volatile material.
  • the grid material is deposited by any process, for example by spraying.
  • the spray in question uses a gas discharge in a bulb containing a gaseous compound of the body to be deposited.
  • the part to be covered is brought to a potential attracting the ions of the body in question.
  • the reserves 4 are then eliminated by heating the assembly to 200 to 300 ° C; the reserves 4 volatilize by tearing the metallic film in its parts 5; there remain on the face 2 the parts 6 which constitute the integrated grid, as shown in the fragment of FIG. 3f.
  • the material constituting the grid is chosen from those with high output work, and therefore is non-emissive at the operating temperature of the cathode, even when it is in the vicinity of areas rich in barium. It is, for example, within the framework of the invention, without this being limiting thereof, of binary mixtures such as W, Zr or W, ZrSi 2 or W, ZrB 2 or W, ZrC or else W, WC.
  • the method described makes it possible, by means of a few additional operations, to integrate the second grid of the cathode assemblies at the cathode, the grid G 2 which was discussed above.
  • the problem of grid alignment is then solved by itself and the interception removed.
  • the choice of a metal with high output work ensures, as for the first, the non-emissivity of this second grid.
  • a thick layer 9, of 50 to 100 ⁇ m, of boron nitride (BN) or of alumina (AI 2 0 3 ) is then deposited, for example by the same process (fig. 4b).
  • layer 9 The role of layer 9 is to isolate the two grids between them; as for the carbon layer 8 and that deposited subsequently on the layer 9, they have a role of chemical separation between the alumina layer and the non-emissive metals constituting the gilles.
  • the presence of the carbon layers also facilitates the break between the parts 5 and 6 at the time of the volatilization of the reserve material 4.
  • the materials cited for the constitution of the layers such as 9 were preferably non-limiting; they can generally be chosen from electrical insulators.
  • a cathode with an integrated double grid is thus obtained.
  • the two grids are superimposed and separated by the remaining parts of the carbon and alumina layers.
  • cathodes both with one and with two integrated grids, are those known in the art, namely high power tubes for ultra-high frequencies, and in particular traveling wave tubes, the optics of which include cylindrical cathodes with a concave emissive surface like those shown.

Landscapes

  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Solid Thermionic Cathode (AREA)
  • Microwave Tubes (AREA)
EP81400577A 1980-04-18 1981-04-10 Procédé de réalisation d'une cathode imprégnée à grille intégrée, cathode obtenue par ce procédé, et tube électronique muni d'une telle cathode Expired EP0038742B1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR8008708A FR2481000A1 (fr) 1980-04-18 1980-04-18 Procede de realisation d'une cathode impregnee a grille integree, cathode obtenue par ce procede, et tube electronique muni d'une telle cathode
FR8008708 1980-04-18

Publications (2)

Publication Number Publication Date
EP0038742A1 EP0038742A1 (fr) 1981-10-28
EP0038742B1 true EP0038742B1 (fr) 1983-11-23

Family

ID=9241054

Family Applications (1)

Application Number Title Priority Date Filing Date
EP81400577A Expired EP0038742B1 (fr) 1980-04-18 1981-04-10 Procédé de réalisation d'une cathode imprégnée à grille intégrée, cathode obtenue par ce procédé, et tube électronique muni d'une telle cathode

Country Status (5)

Country Link
US (1) US4459323A (enrdf_load_stackoverflow)
EP (1) EP0038742B1 (enrdf_load_stackoverflow)
JP (1) JPS56167232A (enrdf_load_stackoverflow)
DE (1) DE3161478D1 (enrdf_load_stackoverflow)
FR (1) FR2481000A1 (enrdf_load_stackoverflow)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5418070A (en) * 1988-04-28 1995-05-23 Varian Associates, Inc. Tri-layer impregnated cathode
KR910005090B1 (en) * 1989-06-02 1991-07-22 Samsung Electronic Devices Method of making the spacer of display device

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE966552C (de) * 1939-10-17 1957-08-22 Electricitaets Ges Sanitas Mit Anordnung von Quarzkristallen bei Ultraschallsendern
DE2139297A1 (de) * 1971-08-05 1973-02-15 Siemens Ag Verfahren zur herstellung gitterfoermiger, elektrisch leitfaehiger belegungen
DE2602659A1 (de) * 1975-01-31 1976-08-05 Grasso Koninkl Maschf Rotationsverdraengungskompressor mit kapazitaetsregelung

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3694260A (en) * 1970-05-21 1972-09-26 James E Beggs Bonded heater,cathode,control electrode structure and method of manufacture
US3967150A (en) * 1975-01-31 1976-06-29 Varian Associates Grid controlled electron source and method of making same
DE2535467C2 (de) * 1975-08-08 1985-06-05 Licentia Patent-Verwaltungs-Gmbh, 6000 Frankfurt Verfahren zum Herstellen einer Kathode einer gittergesteuerten Leistungsröhre
US4096406A (en) * 1976-05-10 1978-06-20 Varian Associates, Inc. Thermionic electron source with bonded control grid
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

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE966552C (de) * 1939-10-17 1957-08-22 Electricitaets Ges Sanitas Mit Anordnung von Quarzkristallen bei Ultraschallsendern
DE2139297A1 (de) * 1971-08-05 1973-02-15 Siemens Ag Verfahren zur herstellung gitterfoermiger, elektrisch leitfaehiger belegungen
DE2602659A1 (de) * 1975-01-31 1976-08-05 Grasso Koninkl Maschf Rotationsverdraengungskompressor mit kapazitaetsregelung

Also Published As

Publication number Publication date
EP0038742A1 (fr) 1981-10-28
US4459323A (en) 1984-07-10
FR2481000B1 (enrdf_load_stackoverflow) 1982-08-20
DE3161478D1 (en) 1983-12-29
FR2481000A1 (fr) 1981-10-23
JPS56167232A (en) 1981-12-22

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