EP0028954A1 - Thermionic cathode, process for manufacturing it and electron tube incorporating such a cathode - Google Patents

Thermionic cathode, process for manufacturing it and electron tube incorporating such a 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
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Prior art keywords
cathode
matrix
mixture
output work
high output
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German (de)
French (fr)
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Arvind Shroff
Pierre Palluel
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Thales SA
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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
    • 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.

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  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Solid Thermionic Cathode (AREA)
  • Manufacture Of Alloys Or Alloy Compounds (AREA)
  • Microwave Tubes (AREA)

Abstract

La cathode selon l'invention est constituée d'une matrice frittée (1) et d'un filament chauffant (4), la dite matrice étant faite d'un mélange (2) de poudres de tungstène et d'un autre métal réfractaire à haut travail de sortie et recouverte d'un film (3) de métal réfractaire à haut travail de sortie.The cathode according to the invention consists of a sintered matrix (1) and a heating filament (4), said matrix being made of a mixture (2) of tungsten powders and of another metal refractory to high output work and covered with a film (3) of refractory metal with high output work.

Description

La présente invention concerne une cathode thermo-ionique et son procédé de fabrication. De telles cathodes trouvent leur domaine d'application dans les tubes électroniques, tubes à constantes localisées comme les triodes et les tétrodes, ou tubes à constantes réparties comme les klystrons et les magnétrons utilisés en hyperfréquences.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.

L'invention concerne également de tels tubes électroniques.The invention also relates to such electronic tubes.

La puissance développée par les tubes électroniques à des hyperfréquences très élevées est limitée notamment par la densité de courant produite par la cathode.The power developed by electronic tubes at very high frequencies is limited in particular by the current density produced by the cathode.

Il existe depuis longtemps des cathodes thermo-ioniques constituées par une matrice en tungstène imprégnée d'aluminate de baryum et de calcium, dans des proportions variables. Les performances de ces cathodes sont de l'ordre de 1 à 3 A/cm2, suivant les compositions d'aluminates utilisés et pour des températures comprises entre 1000 et 1035°C. On a proposé dans l'art antérieur diverses solutions afin d'améliorer les performances de ces cathodes. Parmi ces solutions, l'une consiste à déposer en surface un métal réfractaire à haut travail de sortie tel que l'iridium, l'osmium, le ruthénium, le rhénium. Le gain en densité de courant pour une même température est d'un facteur 3 environ.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.

Le gain en température pour une même densité de courant est de l'ordre de 80°C.The temperature gain for the same current density is of the order of 80 ° C.

Une solution plus récente consiste non plus à déposer à la surface de la cathode un film en métal réfractaire à haut travail de sortie, mais à mélanger à la poudre de tungstène ce dit métal dans des proportions variables allant de quelques 10% à 80%, et ensuite à imprégner la cathode. Les caractéristiques d'émission électronique de ces cathodes sont, suivant le métal utilisé dans le mélange, de 2 à 5 fois supérieures à celles des cathodes en tungstène seul.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.

Voir en particulier le brevet français 77/18822 publié sous le n° 2 356 263.See in particular French patent 77/18822 published under No. 2,356,263.

Une étude expérimentale de ces trois types de cathodes : imprégnée simple, imprégnée recouverte, imprégnée mixte, a permis, à partir d'un réseau de courbes donnant le travail de sortie de la cathode en fonction de la température pour ces différents types de cathodes, de comparer les performances des dites cathodes.An experimental study of these three types of cathodes: simple impregnated, covered impregnated, mixed impregnated, made it possible, from a network of curves giving the output work of the cathode as a function of the temperature for these different types of cathodes, to compare the performance of said cathodes.

Ces courbes ont la forme de guirlandes et présentent un minimum pour une température voisine de la température optimale qui correspond au recouvement optimal de la-cathode. On constate un abaissement du travail de sortie de la cathode aux températures inférieures à la température optimale pour les courbes correspondant aux cathodes imprégnées recouvertes.These curves have the form of garlands and have a minimum for a temperature close to the optimal temperature which corresponds to the optimal recovery of the cathode. There is a lowering of the cathode output work at temperatures below the optimal temperature for the curves corresponding to the coated impregnated cathodes.

On constate également un abaissement du minimum de la courbe dans le cas des cathodes imprégnées mixtes.There is also a lowering of the minimum of the curve in the case of mixed impregnated cathodes.

Partant de ces constatations, la Demanderesse a entrepris des essais pour la réalisation d'une cathode imprégnée mixte et recouverte. La courbe donnant le travail de sortie de la cathode en fonction de la température cumule les deux effets présents dans le cas des cathodes imprégnée mixte et imprégnée recouverte prises isolément. Autrement dit on constate à la fois un abaissement du minimum de la courbe et un abaissement du travail de sortie aux températures inférieures à la température optimale.On the basis of these observations, the Applicant undertook tests for the production of a mixed and covered impregnated cathode. The curve giving the cathode output work as a function of temperature combines the two effects present in the case of mixed impregnated and covered impregnated cathodes taken in isolation. In other words, there is both a lowering of the minimum of the curve and a lowering of the output work at temperatures below the optimal temperature.

Les performances d'une telle cathode ·atteignent 10 à 20 A/cm2 à une température comprise entre 1300 et 1350 K.The performance of such a cathode · reaches 10 to 20 A / cm2 at a temperature between 1300 and 1350 K.

L'invention sera mieux comprise en se reportant à la description qui suit et aux figures jointes qui représentent.

  • Figure 1, le diagramme travail de sortie (φ) en eV en fonction de la température absolue de fonctionnement (T)K pour les différents types de cathodes de l'art antérieur.
  • Figure 2, le diagramme travail de sortie (φ) en fonction de la température de fonctionnement (T)K pour une cathode selon l'invention.
  • Figure 3, le schéma d'une cathode selon l'invention.
The invention will be better understood by referring to the description which follows and to the attached figures which represent.
  • Figure 1, the output work diagram (φ) in eV as a function of the absolute operating temperature (T) K for the different types of cathodes of the prior art.
  • Figure 2, the output work diagram (φ) as a function of the operating temperature (T) K for a cathode according to the invention.
  • Figure 3, the diagram of a cathode according to the invention.

La figure 1 représente un réseau de courbes donnant le travail de sortie Ó en eV en fonction de la température de fonctionnement TK pour les différents types de cathodes de l'art antérieur.Figure 1 represents a network of curves giving the work output Ó in eV as a function of the operating temperature T K for the different types of cathodes of the prior art.

La courbe 1 est relative à une cathode constituée d'une matrice en tungstène et imprégnée d'un aluminate de baryum et de calcium. Les courbes 2 et 3 sont relatives à des cathodes constituées d'une matrice de tungstène, imprégnées d'un aluminate de baryum et de calcium et recouvertes d'un film en un métal réfractaire à haut travail de sortie comme l'iridium (courbe 2), l'osmium (courbe 3) le ruthénium ou le rhenium (courbes non représentées). La courbe 4 est relative à une cathode constituée d'une matrice mixte composée d'un mélange de poudres de tungstène et d'un métal réfractaire à haut travail de sortie comme l'un de ceux cités précédemment et imprégnée d'un composé de baryum.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 .

Ces courbes présentent une forme de guirlande avec un minimum aux environs de la température optimale qui correspond au recouvrement optimal de la cathode, cette température optimale se situe aux alentours de 1250 K. De part et d'autre de cette température, on observe une remontée rapide du travail de sortie en ce qui concerne les cathodes imprégnées (courbe 1). Au delà de 1250K
le taux de recouvrement diminue rapidement du fait du déséquilibre entre la vitesse d'évaporation et la vitesse d'approvisionnement du baryum.These curves have a garland shape with a minimum around the optimal temperature which corresponds to the optimal covering of the cathode, this optimal temperature is around 1250 K. On either side of this temperature, we observe a rise fast output work for impregnated cathodes (curve 1). Beyond 1250K
the recovery rate decreases rapidly due to the imbalance between the speed of evaporation and the speed of supply of barium.

En dessous de 1250K, le baryum se recombine à l'aluminate sous jacent pour redonner un produit stable et de ce fait, le recouvrement n'est plus optimal.Below 1250K, the barium recombines with the underlying aluminate to give a stable product and therefore the recovery is no longer optimal.

Pour ce qui est des courbes 2 et 3 (cas des cathodes imprégnées recouvertes), on constate un abaissement de la courbe à basse température. A haute température, ces courbes ont même allure que celle correspondant aux cathodes imprégnées simples ; ceci est du au fait que le film recouvant la cathode rend l'équilibre à la surface plus stable à basse température.As regards curves 2 and 3 (case of coated impregnated cathodes), there is a lowering of the curve at low temperature. At high temperature, these curves have the same appearance as that corresponding to simple impregnated cathodes; this is due to the fact that the film covering the cathode makes the surface equilibrium more stable at low temperature.

Quant à la courbe 4 (cas des cathodes imprégnées mixtes) elle présente les mêmes variations que celles de la courbe 1 (cas des cathodes imprégnées simples) mais le minimum de la courbe se situe plus bas. Les caractéristiques d'émission électronique de ces cathodes sont, suivant le métal utilisé dans le mélange, de 2 à 5 fois supérieures à celles des cathodes imprégnées simples.As for 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.

Si on augmente la proportion du métal réfractaire à haut travail de sortie, mélangé à la poudre de tungstène, au delà de 50%, la densité de courant à champ nul diminue. Le maximum est de 20% dans le cas de l'iridium, de 50% dans le cas de l'osmium.If we increase the proportion of refractory metal with high output work, mixed with tungsten powder, beyond 50%, the current density at zero field decreases. The maximum is 20% in the case of iridium, 50% in the case of osmium.

Le gain en température, pour une même densité de courant, est de l'ordre, de 80° C comme nous le montrent les intersections des courbes (1) (2) (3) (4) avec les droites (a) (b) (c) à densité de courant constante :

Figure imgb0001
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:
Figure imgb0001

La figure 2 représente la courbe donnant le travail de sortie en eV en fonction de la température de fonctionnement TK pour une cathode selon l'invention c'est-à-dire une cathode constituée d'une matrice imprégnée d'un composé de baryum et faite d'un mélange de poudre de deux métaux, le tungstène et un autre métal réfractaire à haut travail de sortie tels l'osmium, l'iridium, le ruthénium, le rhenium, et recouverte d'un film d'un ides métaux cités précédemment.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.

La courbe obtenue présente un minimum inférieur à ceux des courbes de la figure 1.The curve obtained has a minimum lower than that of the curves in Figure 1.

Cette courbe est plate aux températures inférieures à la température optimale.This curve is flat at temperatures below the optimal temperature.

Pour une cathode constituée d'une matrice (W + x) dans des proportions respectives comprises entre 30% et 70%, x étant un métal réfractaire à haut travail de sortie parmi ceux précités, et recouverte d'un film x d'épaisseur comprise entre 5000 A et 10.000Å,onarriveàdesperformancescomprisesentre 10et20A/cm2àune température comprise entre 1300 et 1350 K.For 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 Å, we arrive at performance between 10 and 20 A / cm2 at a temperature between 1300 and 1350 K.

On donne sur la figure 3 un exemple vu schématiquement en coupe d'une cathode selon l'invention, bien que sur une telle figure ne puisse apparaître le fait que la matrice 1 est constituée d'un mélange de deux poudres à savoir le tungstène et un autre métal réfractaire à haut travail de sortie. On admettra que la partie couverte de points représentée par l'indice 2 est composée d'un tel mélange. Cette matrice 1 est recouverte d'un film 3 en un métal réfractaire à haut travail de sortie.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.

Il est à noter que l'épaisseur de ce film est d'environ 10.000A et que l'échelle n'est pas respectée sur la figure. A cette matrice 1 est incorporé en outre un filament 4 comportant une pellicule isolante 5.It should be noted that the thickness of this film is approximately 10,000A and that the scale is not respected in the figure. In this matrix 1 is also incorporated a filament 4 comprising an insulating film 5.

Selon un mode de préparation d'une cathode selon l'invention, on mélange sans liant, à poids égal, de la poudre de tungstène et d'un autre métal réfractaire à haut travail de sortie, ayant une distribution granulométrique assez voisine.According to one method of preparing a cathode according to the invention, tungsten powder and another refractory metal with high output work, having a fairly similar particle size distribution, are mixed without binder, for equal weight.

Le mélange ainsi obtenu est pressé entre 7 et 10 tonnes au cm2 et ensuite préfritté sous hydrogène à une température de brillance comprise entre 1100° CB et 1300°CB pendant environ 12h. Les échantillons ainsi obtenus sont frittés sous vide à une température de brillance comprise entre 1850 et 1900° CB. Ils sont ensuite imprégnés d'aluminates de baryum et de calcium. L'excédent d'aluminate présent à la surface est éliminé chimiquement par dissolution dans un acide minéral ou organique. On effectue alors le dépôt du film mince par pulvérisation cathodique ou par évaporation.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.

Claims (5)

1. Cathode thermo-ionique composée d'une matrice (1) en un métal en poudre fritté, imprégnée d'un composé de baryum, et d'un filament chauffant (4) associé à cette matrice, caractérisée en ce que cette matrice est constituée d'un mélange (2) de deux métaux, le tungstène et un autre métal réfractaire à haut travail de sortie, et en ce que cette matrice est recouverte d'un film (3) de métal réfractaire à haut travail de sortie.1. Thermionic cathode composed of a matrix (1) of a sintered powder metal, impregnated with a barium compound, and of a heating filament (4) associated with this matrix, characterized in that this matrix is consisting of a mixture (2) of two metals, tungsten and another refractory metal with high output work, and in that this matrix is covered with a film (3) of refractory metal with high output work. 2. Cathode thermo-ionique selon la revendication 1 caractérisée en ce que la matrice (1) est constituée d'un mélange (2) de poudre de tungstène et d'iridium dans des proportions respectives comprises entre 30% et 70% et en ce que le film (3) le recouvrant est de l'iridium et a une épaisseur comprise entre 5000 A et 10.000A.2. thermionic cathode according to claim 1 characterized in that the matrix (1) consists of a mixture (2) of tungsten powder and iridium in respective proportions of between 30% and 70% and in that the film (3) covering it is iridium and has a thickness of between 5000 A and 10,000A. 3. Cathode thermo-ionique selon la revendication 1, caractérisée en ce que la matrice (1) est constituée d'un mélange (2) de poudre de tungstène et d'osmium dans des proportions respectives comprises entre 30% et 70% et en ce que le film (3) la recouvrant est de l'osmium et a une épaisseur comprise entre 5000 A et 10.000A.3. thermionic cathode according to claim 1, characterized in that the matrix (1) consists of a mixture (2) of tungsten powder and of osmium in respective proportions of between 30% and 70% and in that the film (3) covering it is osmium and has a thickness of between 5000 A and 10,000A. 4. Procédé de fabrication d'une cathode selon la revendication 1, comportant les étapes successives suivantes : a) mélange de poudres de tungstène et d'un autre métal réfractaire à haut travail de sortie, b) pressage du mélange entre 7 et 10 tonnes/cm2, c) préfrittage sous hydrogène entre 1100° CB et 1300° CB pendant environ 12h. d) frittage sous vide à une température comprise entre 1850 et 1900° CB, e) imprégnation d'aluminate de baryum et de calcium, f) élimination de l'excédent d'aluminate présent à la surface par un procédé chimique, g) dépôt du film de métal réfractaire à haut travail de sortie par pulvérisation cathodique. 4. Method for manufacturing a cathode according to claim 1, comprising the following successive steps: a) mixture of tungsten powders and another refractory metal with high output work, b) pressing the mixture between 7 and 10 tonnes / cm2, c) pre-sintering under hydrogen between 1100 ° C B and 1300 ° C B for approximately 12 hours. d) vacuum sintering at a temperature between 1850 and 1900 ° C. B , e) impregnation of barium aluminate and calcium, f) removal of the excess aluminate present on the surface by a chemical process, g) deposition of the refractory metal film with high output work by sputtering. 5. Tube électronique pour hyperfréquences, comportant une cathode d'émission thermo-ionique, des électrodes de commande et d'accélération coopérant avec cette cathode pour la production d'un faisceau d'électrons, et des circuits résonnants en interaction, en fonctionnement, avec ledit faisceau, caractérisé en ce que ladite cathode est une cathode selon l'une des revendications 1 à 3.5. Microwave electronic tube, comprising a thermionic emission cathode, control electrodes and of acceleration cooperating with this cathode for the production of an electron beam, and resonant circuits interacting, in operation, with said beam, characterized in that said cathode is a cathode according to one of claims 1 to 3 .
EP80401501A 1979-11-09 1980-10-22 Thermionic cathode, process for manufacturing it and electron tube incorporating such a cathode Ceased EP0028954A1 (en)

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FR7927715 1979-11-09
FR7927715A FR2469792A1 (en) 1979-11-09 1979-11-09 THERMO-IONIC CATHODE, ITS MANUFACTURING METHOD, AND ELECTRONIC TUBE INCORPORATING SUCH A CATHODE

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EP (1) EP0028954A1 (en)
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FR (1) FR2469792A1 (en)

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DE3125915A1 (en) * 1981-07-01 1983-01-20 Licentia Patent-Verwaltungs-Gmbh, 6000 Frankfurt Process for producing a dispenser cathode and apparatus for carrying out the process
FR2515869A1 (en) * 1981-10-29 1983-05-06 Varian Associates ELECTRONIC TUBE AND CATHODE WITH HIGH EMISSION IMPREGNATION
EP0157634A2 (en) * 1984-04-02 1985-10-09 Varian Associates, Inc. Tungsten-iridium impregnated cathode
EP0441698A1 (en) * 1990-02-09 1991-08-14 Thomson Tubes Electroniques Impregnated cathode manufacturing procedure and cathode obtained therewith

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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
EP0143222B1 (en) * 1983-09-30 1987-11-11 BBC Aktiengesellschaft 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 (en) * 1989-04-22 1999-12-02 Aeg Elektronische Roehren Gmbh Investment material, in particular for cathodes of electron tubes, method for producing such an investment material and use of such an investment material
RU2683243C1 (en) * 2017-10-03 2019-03-27 Анатолий Степанович Плахотник Magnetron with thin cathode
CN109065420A (en) * 2018-08-09 2018-12-21 中国电子科技集团公司第十二研究所 A kind of hot cathode and preparation method thereof with three-dimensional structure surface

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Cited By (7)

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Publication number Priority date Publication date Assignee Title
DE3125915A1 (en) * 1981-07-01 1983-01-20 Licentia Patent-Verwaltungs-Gmbh, 6000 Frankfurt Process for producing a dispenser cathode and apparatus for carrying out the process
FR2515869A1 (en) * 1981-10-29 1983-05-06 Varian Associates ELECTRONIC TUBE AND CATHODE WITH HIGH EMISSION IMPREGNATION
EP0157634A2 (en) * 1984-04-02 1985-10-09 Varian Associates, Inc. Tungsten-iridium impregnated cathode
EP0157634A3 (en) * 1984-04-02 1986-01-08 Varian Associates, Inc. Tungsten-iridium impregnated cathode
EP0441698A1 (en) * 1990-02-09 1991-08-14 Thomson Tubes Electroniques Impregnated cathode manufacturing procedure and cathode obtained therewith
FR2658360A1 (en) * 1990-02-09 1991-08-16 Thomson Tubes Electroniques PROCESS FOR MANUFACTURING AN IMPREGNATED CATHODE AND CATHODE OBTAINED BY THIS PROCESS.
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

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JPS5679830A (en) 1981-06-30
US4393328A (en) 1983-07-12
FR2469792B1 (en) 1982-10-01
FR2469792A1 (en) 1981-05-22

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