EP0087826B1 - Cathode thermo-ionique et son procédé de fabrication - Google Patents

Cathode thermo-ionique et son procédé de fabrication Download PDF

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Publication number
EP0087826B1
EP0087826B1 EP83200139A EP83200139A EP0087826B1 EP 0087826 B1 EP0087826 B1 EP 0087826B1 EP 83200139 A EP83200139 A EP 83200139A EP 83200139 A EP83200139 A EP 83200139A EP 0087826 B1 EP0087826 B1 EP 0087826B1
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European Patent Office
Prior art keywords
cathode
layers
emitter
emitter material
base material
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EP83200139A
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German (de)
English (en)
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EP0087826A2 (fr
EP0087826A3 (en
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Georg Dr. Gärtner
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Koninklijke Philips NV
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Philips Patentverwaltung GmbH
Philips Gloeilampenfabrieken NV
Koninklijke Philips Electronics NV
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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
    • 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
    • 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 thermionic cathode with a cathode body, which consists of a high-melting base material and a supply of emitter material, and with an electron-emitting monolayer on the surface of the cathode body, the monolayer being supplemented from the supply of emitter material during operation of the cathode.
  • the invention further relates to a method for producing such a thermionic cathode.
  • cathodes are also referred to as delivery cathodes or monolayer cathodes.
  • Thermionic monolayer cathodes with thorium as the emitter material, i.e. as an electron-emitting substance, on tungsten as a high-melting base material, i.e. as a base matrix, have been known for a long time (DE-A-1 439 890) and have been investigated in detail at an early stage, but because of their wide commercial distribution due to their good vacuum behavior, their quite high emission and their favorable properties when used in UHF and Microwave tubes require a further improvement, especially in terms of emissions, due to increased requirements.
  • such thermionic monolayer cathodes consist of a base matrix made of refractory metal, into which emitter material is embedded or in the form of a compound that diffuses to the surface of the cathode at the operating temperature in the form of atoms, for example as a result of grain boundary diffusion, volume diffusion or through pores, and there forms or supplements a surface monolayer.
  • the formation of a monolayer, ie an approximately monoatomic layer of emitter atoms on the surface is supported by the increasing desorption with a greater degree of coverage.
  • Th- [W] cathodes Th is released from Th0 2 thermally or preferably by reaction with W 2 C and diffuses along the grain boundaries to the tungsten surface.
  • the dipole field between the monolayer and the underlying atoms of the base material brings about an additional reduction in the emitter work function for thermionic electrons, so that monolayer cathodes have a higher electron emission than cathodes made of pure emitter material.
  • the work function for pure Th at about 3.5 eV, while for a Th monolayer on tungsten it is only 2.8 eV.
  • the cathode will only function properly if the entire emitting surface of this monolayer, i.e. is covered by a monoatomic film. This condition becomes critical at higher temperatures at which sufficient coverage and thus emission are no longer guaranteed due to strong desorption of the emitter atoms.
  • Th- [W] cathodes such a drop in emissions occurs at around 2200 K. The emission finally drops to that of pure tungsten.
  • the temperature at which the drop in emissions occurs depends, in particular in the case of monolayer cathodes with subsequent delivery of the emitter material, via grain boundary diffusion on the grain size. Since the emitter atoms spread on the surface by surface diffusion, the sources for the emitter atoms being the grain boundaries, smaller crystallites naturally result in better coverage with the same diffusion length.
  • This theoretically required diffusion length is, however, orders of magnitude larger than that which can be calculated from the mean grain sizes and the temperature of the drop in emissions. I.
  • the invention has the object of specifying a suitable cathode structure and of creating a method for producing this structure, with which it is possible to avoid the edge effect in Th- [W] and analog monolayer cathodes and also to emit the fine crystallinity of the base material and a suitable texture, as well as by ensuring the thermal stability of the texture, and to keep it stable over time.
  • the cathode body consists of a sequence of layers of base material and intermediate layers with a high concentration of emitter material, and in that the macroscopic cathode surface extends obliquely to the main surfaces of at least that part of the layers located near the macroscopic cathode surface.
  • the layer sequence is preferably produced by alternating deposition of the high-melting base material and the electron-emitting substance from the gas phase, and then the macroscopic emitting surface is produced by an angle grinding.
  • a preferred cathode structure according to the invention looks as follows:
  • the cathode consists of a layer sequence of layers arranged obliquely to the emitting cathode surface, which alternately consist primarily of high-melting base material and of emitter material.
  • the thickness of these layers is in the range of up to 0.01 1 1m, the emitter material layers being significantly thinner than the base material layers.
  • the electron-emitting substance which is preferably an element of the scandium group, in particular thorium, or one of its compounds, is characterized in that it essentially reaches the surface by grain boundary diffusion through the high-melting base material, in particular tungsten, and spreads there by surface diffusion.
  • W, Mo, Ta, Nb, Re and / or C are also used as base materials, the composition of the base material being the same or different in the individual layers of the layer sequence.
  • the surface has a stepped structure, the strongly emitting treads of the steps (hereinafter also called step-out steps) forming the continuation of the layers of emitter material.
  • the emitter atoms diffuse directly to the outlet stages without edge inhomogeneities and form a monolayer there.
  • the base material layers have a suitable preferred orientation with respect to the layer normal, for Th [W] cathodes this is, for example, the ⁇ 111> orientation for the W base material.
  • the cathode material is finely crystalline with grain sizes: - 5 1 ⁇ m. It is also favorable if the grain diameters are somewhat larger than the step widths.
  • the temporal stability of the texture is achieved by doping the base material with components which are only slightly or not soluble at all. Further doping in the edge zone of the emitter material layers serve to better release the emitter atoms if the emitter material is in the form of a compound.
  • the surface of the inclined layer structure is covered with a polycrystalline, optionally preferred-oriented layer of base material or another material which, in combination with the emitter monolayer, brings about a significant reduction in the electron work function.
  • the boundary of the sloping layer towards the top layer is usually smooth, without pronounced steps.
  • the top layer is finely crystalline.
  • the cathode according to the invention is preferably produced in three processing steps.
  • a layer sequence is first produced by alternating deposition of the high-melting base material and the electron-emitting substance from the gas phase.
  • a method for alternating deposition of base material and electron-emitting substance has been proposed in EP-A2-0 081 270; this method and its configurations (also for simultaneous deposition) can also be used in the method according to the invention.
  • the layers are applied by reactive deposition such as CVD processes, pyrolysis, cathode sputtering, vacuum condensation or plasma sputtering.
  • PCVD plasma-activated CVD method
  • the chemical reaction can also be excited or induced by high-frequency excitation by photons or by electron impact.
  • Th-W Applied to the preferred material combination Th-W, this means that a layer sequence of pure tungsten or doped with a stabilizer is alternately deposited with Th0 2 layers from the gas phase on a suitable substrate. If organometallic starting compounds are used, the Th-CVD also carburizes the base material deposited with it. In a preferred embodiment, tungsten is deposited in a preferred-oriented manner by setting the CVD parameters accordingly.
  • the layer sequence is preferably produced by reactive deposition with temporal variation of the parameters, in particular the flow rates of the gases involved in the reaction and / or the substrate temperature.
  • the temporal variation of the parameters of the reactive deposition takes place essentially periodically (alternating CVD method).
  • the layers are ground at an angle after the deposition, preferably at an angle of 20 to 70 °, in particular 45 °.
  • the bevel cut according to the invention takes place e.g. by mechanical processing, such as grinding or milling, and / or mechanical-chemical micropolishing, or by cutting to size with the aid of a laser beam.
  • a step-like structure of the surface is produced by etching.
  • a suitable etchant for the combination Th-W is, for example, a 3% by weight solution of H 2 0 2 .
  • the step-like microstructure of the surface can also be created using other methods. This includes, for example, the local evaporation of base material using an intense laser beam or electron beam, which is guided over the ground surface in accordance with the trailing edges of the emitter layers.
  • the slanted emitter material intermediate layers with their lower mechanical stability are in the latter process combination a cause for the emergence of the step structure or for the inhibition of the base material recrystallization on the emitter material intermediate layer.
  • the steps are designed so that their treads are in the extension of the layers with a high concentration of emitter material, while the step grooves are perpendicular to it.
  • the emitter material can diffuse directly from the layers of high emitter material concentration to the surface of the outlet stages - and without any strong desorption at grain boundaries.
  • An appropriately set preferred orientation of the base layers also ensures that the lowest work function from the emitter-monolayer base combination is achieved everywhere on the outlet stages.
  • the crystallites in the step throats are of course still randomly oriented. However, their share of the total area can be determined by a shallower angle of inclination of the layers than 45 ° - e.g. 25 ° - can be greatly reduced to the macro surface.
  • the production method according to the invention is supplemented by a simultaneous deposition of additional dopants.
  • Th [W] cathodes If the temperature of Th- [W] c cathodes is increased above the normal working temperature of 2000 to 2100 K, then due to increasing Th-desorption from the monolayer, ie decreasing Th-coverage, a significant decrease in the emission occurs, in particular from 2200 K, so that an increase in emissions by increasing the temperature can no longer be realized. This drop in emissions depends critically on the mean grain diameter and only occurs at higher temperatures, the smaller the mean grain size.
  • an average tungsten grain diameter of i 1 ⁇ m means an extension of the usable temperature range to ;;:; 2400 K.
  • Such small grain sizes can practically only be produced using the CVD process, and therefore only through a suitable choice of parameters.
  • this very fine crystallinity must also remain stable with regard to longer thermal loads. If, for example, the grain size increases too much due to recrystallization during operation of the cathode, this finally causes a decrease in the emission current and thus a shorter service life due to the decrease in the monoatomic coverage.
  • the same stability requirement also applies to the texture, ie the preferred orientation set on the surface must be maintained.
  • This recrystallization is prevented analogously to the mechanical stabilization of a carrier layer by adding a substance which is insoluble in the crystal lattice of the cover layer material and which is simultaneously separated from the gas phase, and at the same time also stabilizes the texture.
  • doping with Th, Th0 2 , Zr, Zr0 2 , U0 2 , Y, Sc, Y 2 0 3 , S C2 0 3 and Ru are suitable.
  • Th0 2 , Zr0 2 , Y 2 0 3 , S C2 0 3 Ru remain as preferred CVD doping.
  • the doping in particular may also be identical to the emitting substance if Th, Y or Sc form the emitter monolayer.
  • a further processing step can optionally be inserted after grinding, namely the assembly of individual cut facets to form a cathode body of the desired surface geometry, e.g. using an inlay technique.
  • Another possibility which is described in more detail in the exemplary embodiments, is the use of notched substrates (cf. FIG. 4).
  • a polycrystalline cover layer or a preferentially oriented polycrystalline cover layer is applied to the surface produced by angled grinding by means of a deposition from the gas phase. It being expedient to adhere to certain combinations of the deposition parameters, especially the substrate temperature and flow rates of the gas mixture.
  • the cover layer consists of a pure, high-melting metal, such as W, Mo, Ta, Nb, Re, Hf, lr, Os, Pt, Rh, Ru, Zr, or of C and should have a preferred orientation.
  • the material and its texture are chosen so that the work function from the combination of the emitter monolayer and the top layer is even lower than that from the combination of the emitter and the base.
  • the cover layer consists of a metal with a high work function, which reduces the work function accordingly by means of a high dipole moment between the emitter film and the cover layer.
  • a prerequisite for good surface coverage is either fine crystallinity of the cover layer of the emitter material or the presence of sufficient volume diffusion in the cover layer.
  • 1 denotes base layers made of grain-stabilized, ie doped, tungsten. These layers are 1 to 2 1 1m thick.
  • 2 denotes Th monolayers on W ⁇ 111>.
  • 3 denotes intermediate layers made of Th0 2 from 0.1 to 0.5 11 m thick. There is a W 2 C enrichment in the edge zone of the intermediate layer, which serves to release Th from Th0 2 .
  • the intermediate layer 3 can also consist of Th0 2 and W 2 C (as a mixture). 4 indicates the direction of deposition.
  • the entire cathode is usually a flat cathode, which is heated directly or indirectly.
  • the layer sequence itself is achieved by a high-frequency alternating deposition of optionally doped W and Th0 2 .
  • the high-frequency layer sequence is achieved via a computer control of the process, in particular the flow of the individual gaseous components.
  • the substrate temperature is about 500 ° C, the pressure in the reactor 10 to 100 mbar, preferably 40 mbar.
  • the WF 6 flow rate is approximately 30 cm 3 / min at an approximately 10 times H 2 flow rate.
  • the interval is up to a few minutes, especially 1 minute.
  • Ar is also used as the carrier gas for thorium acetylacetonate or fluorinated Th-acetylacetonate and WF 6 Th0 2 or Th0 2 + W 2 C for about 1 minute.
  • Th (C 5 H 7 0 2 ) 4 is in powder form in a saturator flowed through by Ar at about 85 cm 3 / min, which is heated to a temperature of about 160 ° C. or close to the melting point of the Th compound. The reaction temperature is about 20 ° higher.
  • An additional W 2 C enrichment at the edge of 3 is either by briefly (about 8 s) introducing a hydrocarbon-containing gas at the beginning of the new W-CVD interval or by stronger WFg enrichment towards the end of the Th separation, especially in the case of Th Trifluoroacetylacetonat achieved as a starting compound.
  • boronization of the edge zone is also advantageous.
  • doping of W can optionally be dispensed with, since grain stabilization is already caused by the intermediate layers.
  • doping the CVD-W with a substance that is hardly soluble or insoluble in W such as 1% by weight of Th0 2 , Zr0 2 , Y 2 0 3 , S C2 0 3 or Ru, is advantageous.
  • the flow rate of WF 6 is set so high that it just leads to a deposition of W in the ⁇ 111> direction at the respective substrate temperature.
  • the CVD sample is cast or clamped in layers and ground flat at an angle of 45 ° to the growth direction or cut to size using a laser.
  • the remaining sides of the sample are then also ground and provided with an approximately 50 to 150 ⁇ m thick Re or W coating 6 by CVD deposition (FIG. 2).
  • the resulting sample is spotted on a hairpin 7 for heating.
  • the exposed, uncovered, ground cathode surface is again micropolished to a few tenths of a meter and then carefully etched with a structural etchant suitable for W, so that the desired step-like surface structure is obtained.
  • a suitable structure etchant for W is, for example, a 3% by weight solution of H 2 0 2 .
  • the cathode structure described in this exemplary embodiment and its method of manufacture applies not only to the Th-W emitter-base combination, but also to any combination of an emitter with a high-melting metal in a monolayer cathode in which the emitter is essentially supplied via grain boundary diffusion.
  • Such emitter materials are e.g. can also be found in the scandium group: the above cathode structure is also a preferred structure for the combination Y-W and Sc-W.
  • the corresponding acetylacetonates can also be used for the deposition of Y or Sc oxide.
  • a longitudinally ribbed cylinder substrate 8 provides a fairly uniform electron emission density distribution over the circumference of the jacket.
  • By increasing the number of ribs in relation to the circumference it is possible to use substrates of smaller thickness because of the associated reduction in the rib depth, which is advantageous for the cathode heating.
  • the opposite effect such as in the case of cylindrical substrates, use an elliptical cross section and produce an inhomogeneous distribution of the emerging electrons as a result of the very different step widths, which means e.g. four maxima arise in the electron exit density.
  • Ribbed substrates are also advantageously used for the production of cathodes with any surface geometry, e.g. flat substrates with ribbing or substrates with any curved surface with ribbing. In the case of flat cathodes, this saves in particular the facetted assembly of larger areas, for which one would normally use a mosaic or inlay technique. If you use e.g. a macroscopically "flat" substrate as in Fig. 4 with sawtooth-shaped notch, the boundary condition for parallel growth on the inclined notch surfaces is that the reactive deposition from the gas phase takes place in the area regulated by the surface reaction kinetics, i.e.
  • the deposition temperatures must therefore be selected taking into account a turning point in the growth characteristics in the lower temperature range.
  • the notch depths are in the range from 10 to 20 ⁇ m and about 10 to 20 layer sequences are applied.
  • the W layers are again deposited in a ⁇ 111> preferred manner and doped with a structure-stabilizing component.
  • the surface is ground smooth in accordance with the selected substrate geometry, and the surface is provided with micro-stages according to one of the methods specified, the tread surfaces 2 of which in turn correspond to the outlet stages of the intermediate layers 3 of emitter material.
  • the levels are generated, for example, by structure etching.
  • the substrate 8 consists, for example, of molybdenum, in which the notches 9 are produced by mechanical processing.
  • 1 again designates the base material layers, 3 the emitter material intermediate layers, 2 the outlet stages covered with the monoatomic emitter layer and 4 the deposition directions in the CVD deposition.
  • the removed part of the CVD layers is indicated by dashed lines.
  • cathodes according to the invention with a stepped surface are as follows: The most important advantage is based on the suppression of the edge effect. Without strong desorption, the emitter atoms diffuse freely at the grain boundaries near the surface through the outlet stages and form a monolayer there. For Th [W] cathodes according to the invention, because of the much lower edge desorption, the critical temperature shifts upward by about 200 ° and the emission maximum also only occurs at a higher cathode temperature (about 2100 K). Stage cathodes according to the invention thus open up the possibility of also achieving a higher emission current density by increasing the temperature than is customary in the conventional Th [W] cathodes. On the other hand, the consumption of emitter material is lower at the usual operating temperatures, and the service life is consequently extended with the same supply of emitter material.
  • Another advantage is that the effective emitting surface is increased by the step structure; with a cut below 45 ° the magnification factor is approximately 1.4, which is desirable for Th [W] cathodes at temperatures ⁇ 2000 K.
  • Another important advantage of the invention is based on the deposition of the base material layers with that preferred orientation for which the work function of an emitter monolayer on this crystalline-oriented basis is minimal.
  • Th- [W] cathodes this is the ⁇ 111> orientation of W.
  • the outlet stages are oriented in the normal direction to the layering ⁇ 111>; the side surfaces of the steps are statistically oriented and therefore make little contribution to the overall emission. It is therefore expedient to correspondingly increase the preferred area proportion of the run-off stages by means of a flatter ground angle, for example of 30 °, which in turn means an increase in the overall emission curve 11 (FIG. 5).
  • FIG. 5 FIG.
  • FIG. 5 shows the approximate course of the emission current density i s (T) of a stepped Th [W] cathode according to the invention as a function of the cathode temperature T.
  • curve 10 i s (t) are presented for a conventional thoriated W wire cathode.
  • the texture of the W layers is stabilized by additions of approximately 1% by weight, which are practically insoluble in W, for example Th0 2 , Zr0 2 , Y 2 0 3 , Sc 2 0 3 and / or Ru.
  • This doping also causes an inhibition of grain growth, which because of the intermediate layers anyway only plays a role laterally in the base material layers.
  • the diffusion of the emitter material to the surface takes place along the intermediate layers 3 and is not hindered by lateral crystallite growth of the base layers.
  • the sequence of inclined layers which in this case need not have a preferred orientation, is after grinding by reactive deposition from the gas phase with a polycrystalline, preferably preferentially oriented polycrystalline cover layer from base material, e.g. ⁇ 111> W for a Th- [W] cathode, or coated with another refractory material with low work function from the emitter monolayer-top layer combination.
  • the thickness of this cover layer is in the range of approximately 2 to 20 ⁇ m, preferably 5 to 10 ⁇ m.
  • the CVD coating takes place according to the composition of the individual pieces to the desired surface shape.
  • the range of favorable grinding angles in this embodiment of the invention is between 20 ° and 90 °.
  • the most important advantage of this embodiment lies in the subsequent delivery of the emitter material to the surface, undisturbed by grain growth, combined with a high stock and less desorption than e.g. with MK cathodes (metal capillary cathodes), which means an overall increase in the service life in comparison to conventional Th [W] cathodes.
  • MK cathodes metal capillary cathodes
  • the emission is increased by the ⁇ 111> -textured and texture-stabilized cover layer compared to known Th- [W] cathodes.

Claims (16)

1. Cathode thermo-ionique comportant un corps cathodique, qui est constitué par un matériau de base à point de fusion élevé et une réserve en matériau d'émetteur, et une monocouche émettrice d'électrons appliquée sur la surface du corps cathodique, la monocouche étant complétée pendant le fonctionnement de la cathode à partir de la réserve en matériau d'émetteur, caractérisée en ce que le corps cathodique est constitué par une suite de couches (1) en matériau de base et de couches intermédiaires (3) présentant une concentration élevée en matériau d'émetteur, et la surface cathodique macroscopique s'étend de façon oblique au moins par rapport aux surfaces principales de la partie des couches (1, 3), qui se trouvent dans la proximité de la surface cathodique macroscopique.
2. Cathode selon la revendication 1, caractérisée en ce que la surface présente une structure étagée, les girons (2) de l'étage constituant un prolongement des couches intermédiaires (3) en matériau d'émetteur.
3. Cathode selon la revendication 1, caractérisée en ce que sur la surface de la suite de couches inclinées (1, 3) est appliquée une couche de recouvrement polycristalline qui, le cas échéant, présente une orientation préférentielle.
4. Cathode selon la revendication 1, 2 ou 3, caractérisée en ce que le matériau d'émetteur est un élément du groupe de scandium, notamment du thorium, ou l'un de ses composés, et le matériau de base est du tungstène.
5. Cathode selon l'une ou plusieurs des revendications 1 à 4, caractérisée en ce que la suite de couches (1, 3) est constituée par des dépôts alternants de concentrations élevées et basses du matériau d'émetteur.
6. Cathode selon une ou plusieurs des revendications 1 à 5, caractérisée en ce que la surface cathodique macroscopique est disposée de façon à former un angle compris entre 10 et 70°, de préférence 45°, par rapport à la surface principale de la couche (1, 3).
7. Cathode selon l'une ou plusieurs des revendications 1 à 6, caractérisée en ce que dans une zone marginale des couches intermédiaires (3) ou dans les couches intermédiaires (3) mêmes se trouvent du carbone et/ou du bore additionnel(s) dans une concentration de l'ordre de grandeur de la concentration du matériau d'émetteur.
8. Cathode selon l'une ou plusieurs des revendications 1 à 7, caractérisée en ce que les couches (1) en matériau de base présentent une épaisseur comprise entre 0,5 à 20 µm, de préférence 1 à 2 ¡.Lm, et les couches intermédiaires (3) en matériau d'émetteur une épaisseur comprise entre 0,1 à 0,5 um, notamment 0,2 µm, la zone marginale contenant du carbone et/ou du bore présente, le cas échéant, présentant une épaisseur de 0,2 ¡.Lm.
9. Procédé pour la réalisation de la cathode thermo-ionique selon l'une ou plusieurs des revendications 1 à 8, caractèrisé en ce que la suite de couches est réalisée par dépôt alternant du matériau de base à point de fusion élevé et du matériau d'émetteur à partir de la phase gazeuse et la surface macroscopique est réalisée ensuite par chanfreinage.
10. Procédé selon la revendication 9, caractérisé en ce que la suite des couches est réalisée par dépôt réactif avec une variation temporelle des paramètres, notamment le volume d'écoulement du gaz participant à la réaction et/ou de la température du substrat.
11. Procédé selon la revendication 10, caractérisé en ce que la variation temporelle des paramètres du dépôt réactif s'effectue essentiellement périodiquement.
12. Procédé selon la revendication 10 ou 11, caractérisé en ce que les couches de tungstène qui, le cas échéant, sont dopées pour la stabilisation de la structure de, en poids, 2% de Th02, Zr02, Y203, Sc203 et/ou Ru, sont déposées avec orientation préférentielle < 111 > par réglage du paramètre CVD.
13. Procédé selon la revendication 9, 10, 11 et/ou 12 pour la réalisation d'une cathode thermo-ionique selon la revendication 2, caractérisé en ce que la microstructure étagée de la surface s'obtient par
a) décapage respectivement décapage structurel et/ou
b) évaporation locale de matériau à l'aide d'un faisceau électrons et/ou
c) évaporation locale de matériau à l'aide d'un faisceau laser et/ou
d) traitement mécanique de la surface et/ou
e) un traitement thermique.
14. Procédé selon la revendication 9, 10, 11 et/ou 12, pour la réalisation d'une cathode thermo-ionique selon la revendication 3, caractérisé en ce que sur la surface chanfreinée est appliquée, par dépôt à partir de la phase gazeuse, une couche de recouvrement polycristalline qui, le cas échéant, présente une orientation préférentielle.
15. Procédé selon l'une ou plusieurs des revendications 9 à 13, caractérisé en ce qu'un substrat cannelé et/ou rainuré, respectivement entaillé en forme de dents de scie dans la surface qui en section présente une géométrie quelconque, notamment une géométrie plane ou cylindrique, ou un substrat courbé spatiallement de n'importe quelle façon est utilisé pour le dépôt réactif des couches à partir de la phase gazeuse, le recouvrement étant poursuivi jusqu'à obtention d'une épaisseur, qui est au moins égale à la profondeur des entailles, après quoi la surface recouverte est polie essentiellement jusqu'aux faces des entailles du substrat de façon que la suite de couches ainsi formée soit chaque fois inclinée par rapport à de nouvelles surfaces, la direction de recouvrement dans les entailles étant chaque fois déplacée de 90°, après quoi s'obtient la microstructure étagée.
16. Procédé selon l'une ou plusieurs des revendications 9 à 14, caractérisé en ce que non seulement la surface s'obtient par chanfreinage de la couche CVD, mais également les faces de l'épreuve CVD sont polies de façon qu'il se forme une cathode en forme de pillule présentant des surfaces planes macroscopiques et des couches inclinées, dont les faces non émissives sont munies par CVD d'un revêtement en W, Re ou Mo d'environ 20 à 200 um et est ensuite soudée par points sur un fil en forme d'épingle à cheveux réfractaire mince, qui sert de chauffage cathodique direct, ou qui est disposée pour un chauffage indirect comme capot d'une gaine cylindrique, munie d'un filament de tungstène disposé à l'intérieur la réalisation de la surface étagée étant obtenue par micropolissage et décapage structurel après disposition des amenées de chauffage.
EP83200139A 1982-02-18 1983-01-27 Cathode thermo-ionique et son procédé de fabrication Expired EP0087826B1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE3205746 1982-02-18
DE19823205746 DE3205746A1 (de) 1982-02-18 1982-02-18 Thermionische kathode und verfahren zu ihrer herstellung

Publications (3)

Publication Number Publication Date
EP0087826A2 EP0087826A2 (fr) 1983-09-07
EP0087826A3 EP0087826A3 (en) 1984-06-13
EP0087826B1 true EP0087826B1 (fr) 1986-09-03

Family

ID=6156031

Family Applications (1)

Application Number Title Priority Date Filing Date
EP83200139A Expired EP0087826B1 (fr) 1982-02-18 1983-01-27 Cathode thermo-ionique et son procédé de fabrication

Country Status (6)

Country Link
US (1) US4524297A (fr)
EP (1) EP0087826B1 (fr)
JP (1) JPS58155619A (fr)
CA (1) CA1194089A (fr)
DE (2) DE3205746A1 (fr)
ES (2) ES519829A0 (fr)

Families Citing this family (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3446334A1 (de) * 1984-12-19 1986-06-19 Philips Patentverwaltung Gmbh, 2000 Hamburg Verfahren zur herstellung von <111>-vorzugsorientiertem wolfram
JPH0760641B2 (ja) * 1985-02-06 1995-06-28 新日本無線株式会社 マグネトロン用陰極
CA1272504A (fr) * 1986-11-18 1990-08-07 Franz Prein Surface pour decharge electrique
DE3723271A1 (de) * 1987-07-14 1989-01-26 Patent Treuhand Ges Fuer Elektrische Gluehlampen Mbh Kathode fuer eine hochdruckentladungslampe
DE69432174T2 (de) * 1993-11-24 2003-12-11 Tdk Corp Kaltkathoden-elektrodenquellenelement und verfahren zur herstellung desselben
RU2194328C2 (ru) 1998-05-19 2002-12-10 ООО "Высокие технологии" Холодноэмиссионный пленочный катод и способ его получения
US6815876B1 (en) * 1999-06-23 2004-11-09 Agere Systems Inc. Cathode with improved work function and method for making the same
ATE472168T1 (de) * 2000-05-11 2010-07-15 Panasonic Corp Elektronenemissions-dünnfilm, plasma-display- tafel damit und verfahren zu ihrer herstellung
KR100442300B1 (ko) * 2002-01-04 2004-07-30 엘지.필립스디스플레이(주) 음극선관용 음극
WO2007033247A2 (fr) * 2005-09-14 2007-03-22 Littelfuse, Inc. Limiteur de surtension rempli de gaz, compose d'activation, rubans d'amorçage et procede associe
WO2009013685A1 (fr) * 2007-07-24 2009-01-29 Philips Intellectual Property & Standards Gmbh Emetteur d'électrons thermoïonique, méthode pour préparer celui-ci et source radiographique comprenant celui-ci
DE102015211235B4 (de) 2015-06-18 2023-03-23 Siemens Healthcare Gmbh Emitter

Family Cites Families (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2339392A (en) * 1942-10-06 1944-01-18 Rca Corp Cathode
FR1150153A (fr) * 1953-08-01 1958-01-08 France Etat Cathodes thermoémissives pour tubes électroniques à support de rhénium
US2878409A (en) * 1957-04-29 1959-03-17 Philips Corp Dispenser-type cathode and method of making
US3290543A (en) * 1963-06-03 1966-12-06 Varian Associates Grain oriented dispenser thermionic emitter for electron discharge device
GB1137124A (en) * 1964-12-23 1968-12-18 Nat Res Dev Thermionic electron emitter
SU439028A1 (ru) * 1972-08-08 1974-08-05 Е. И. Давыдова, А. Д. Карпенко , В. А. Шишкин Способ изготовлени автоэлектронных катодов
SU510760A1 (ru) * 1974-09-09 1976-04-15 Организация П/Я Х-5263 Катод
CH579824A5 (fr) * 1974-10-25 1976-09-15 Bbc Brown Boveri & Cie
US4019081A (en) * 1974-10-25 1977-04-19 Bbc Brown Boveri & Company Limited Reaction cathode
NL165880C (nl) * 1975-02-21 1981-05-15 Philips Nv Naleveringskathode.

Also Published As

Publication number Publication date
US4524297A (en) 1985-06-18
ES8401674A1 (es) 1983-12-01
DE3205746A1 (de) 1983-08-25
JPS58155619A (ja) 1983-09-16
ES522416A0 (es) 1984-03-01
ES519829A0 (es) 1983-12-01
JPH0447936B2 (fr) 1992-08-05
DE3365755D1 (en) 1986-10-09
EP0087826A2 (fr) 1983-09-07
ES8403243A1 (es) 1984-03-01
EP0087826A3 (en) 1984-06-13
CA1194089A (fr) 1985-09-24

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