EP0010128A1 - Directly heated cathode for an electron tube with coaxial electrode structure and method of making such a cathode - Google Patents

Directly heated cathode for an electron tube with coaxial electrode structure and method of making such a cathode Download PDF

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Publication number
EP0010128A1
EP0010128A1 EP19790102866 EP79102866A EP0010128A1 EP 0010128 A1 EP0010128 A1 EP 0010128A1 EP 19790102866 EP19790102866 EP 19790102866 EP 79102866 A EP79102866 A EP 79102866A EP 0010128 A1 EP0010128 A1 EP 0010128A1
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EP
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Prior art keywords
cathode
hollow cylinder
directly heated
metal layer
thin metal
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EP19790102866
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German (de)
French (fr)
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EP0010128B1 (en
Inventor
Ingo Behling
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Siemens AG
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Siemens AG
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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
    • H01J19/00—Details of vacuum tubes of the types covered by group H01J21/00
    • H01J19/02—Electron-emitting electrodes; Cathodes
    • H01J19/04—Thermionic cathodes
    • H01J19/08—Cathodes heated directly by an electric current

Definitions

  • the invention relates to a directly heated cathode for electron tubes, in particular transmitter tubes, with a coaxial structure of the electrodes and their bushings, which has a hollow cylinder which is fastened at one end to an annular cathode feed and at the other end to a cathode cap which is coaxially in the hollow cylinder extending power supply is supported.
  • Such a directly heated cathode is known for example from DE-AS 24 15 384. From this DE-AS it is also known that for the production of cathodes which are heated directly and which have a metal film as an emission layer, for example tungsten carbide with a thorium film, tungsten wire is used as the carrier. By arranging the wires accordingly, at Transmitter tubes in mesh or needle shape, the required surface and mechanical strength is achieved. The structure of the cathodes inevitably results in an inhomogeneous cathode surface, which has an effect on the electrode system. There are also difficulties in manufacturing cathodes with narrow wire gaps.
  • the object of the invention is therefore to create a directly heated cathode, the carrier of which is not made of wire, so that inhomogeneities on the cathode surface are avoided.
  • a directly heated cathode for electron tubes, in particular transmitter tubes, of the type mentioned at the outset according to the invention that the hollow cylinder consists of pyrolytic graphite and is coated with a thin metal layer as an emission layer.
  • the thin metal layer preferably consists of tungsten carbide and thorium or a thorium oxide.
  • the thin metal layer (cathode layer), preferably made of tungsten carbide and thorium or thorium oxide, can advantageously be applied to the hollow cylinder of the cathode consisting of pyrolytic graphite by the following methods.
  • Either thorium-tungsten powder is deposited cataphoretically as a thin metal layer onto the hollow cylinder and then sintered on, or a thin metal layer consisting of thorium and tungsten is vapor-deposited onto the hollow cylinder with the aid of an electron beam.
  • Another expedient method consists in that thorium-tungsten is deposited as a thin metal layer from the gas phase on the hollow cylinder (carrier body) consisting of pyrolytic graphite.
  • the directly heated cathodes according to the invention have the following advantages, in particular over mesh cathodes.
  • the stability of the cathodes is determined by the pyrolytic graphite and is much greater in comparison to tungsten at the operating temperatures.
  • flat cathodes or structured cathodes can be produced. Bulging of the cathode cylinder due to a length expansion when the electron tube is switched on no longer occurs.
  • the figure shows a longitudinal section as an exemplary embodiment of a transmitter triode with coaxially arranged cylindrical electrodes and bushings. These include - the central, directly heated cathode, which is connected to the feed-through plate or inner cathode connecting ring 5 and the support tube 6 (outer cathode connection).
  • the hollow cylinder 1 of the cathode is initially surrounded by the grid electrode 3 and then by the anode 4 with the associated support tubes 7, 11.
  • the actual discharge vessel is formed, in addition to the anode 4 designed as an external anode, essentially by the feed-through foot, which is used in conventional metal-ceramic technology alternately composed of metal support tubes or discs and ceramic rings.
  • the respective cathode fastenings are provided with the reference number 2.
  • a flexible power supply line 8 is attached to the cathode cap 9 and leads from the inner cathode connection 5 to the hollow cylinder 1.
  • the hollow cylinder 1 of the cathode consists of pyrolytic graphite and is coated with a thin metal layer 10, preferably of tungsten carbide and thorium, as the emission layer.

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  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Solid Thermionic Cathode (AREA)
  • Microwave Tubes (AREA)
  • Discharge Lamp (AREA)

Abstract

1. A directly heated cathode for electron tubes, in particular transmitter tubes, which has a coaxial structure of the electrodes and their lead-ins, which is secured at one end to an annular cathode lead (12) and at the other end to a cathode cap (9) which is supported on a current supply lead (6) running coaxially in the hollow cylinder, characterized in that the hollow cylinder (1) consists of pyrolytic graphite and is coated with a thin metal layer (10) as emission layer.

Description

Die Erfindung betrifft eine direkt geheizte Kathode für Elektronenröhren, insbesondere Senderöhren, mit koaxialem Aufbau der Elektroden und deren Durchführungen, die einen Hohlzylinder aufweist, der an einem Ende an einer ringförmigen Kathodenzuführung und am anderen Ende an einer Kathodenkappe befestigt ist, die an einer koaxial in dem Hohlzylinder verlaufenden Stromzuführung gehaltert ist.The invention relates to a directly heated cathode for electron tubes, in particular transmitter tubes, with a coaxial structure of the electrodes and their bushings, which has a hollow cylinder which is fastened at one end to an annular cathode feed and at the other end to a cathode cap which is coaxially in the hollow cylinder extending power supply is supported.

Eine derartige direkt geheizte Kathode ist beispielsweise aus der DE-AS 24 15 384 bekannt. Aus dieser DE-AS geht weiterhin als bekannt hervor, daß man für die Herstellung von Kathoden, die direkt geheizt werden und einen Metallfilm als Emissionsschicht aufweisen, z.B. Wolframkarbid mit Thoriumfilm, als Träger Wolfram-Draht benutzt. Durch entsprechende Anordnung der Drähte, bei Senderöhren in Maschen- oder Nadelform, wird die benötigte Oberfläche und mechanische Festigkeit erreicht. Durch den Aufbau der Kathoden ergibt sich zwangsläufig eine inhomogene Kathodenoberfläche, welche Auswirkungen auf das Elektrodensystem hat. Es ergeben sich auch Schwierigkeiten bei der Herstellung von Kathoden mit engen Drahtabständen. Bei Senderöhren mit engen Gitter-Kathodenabständen und Maschenkathoden wirken sich die unterschiedlichen Abstände (Außendraht und Innendraht der Maschenkathode) nachteilig auf die elektrischen Daten der Elektronenröhre aus.
Kathoden mit einer homogenen Oberfläche sind bisher nur als Oxid-Matrix- oder Vorratskathoden bekannt. Bestimmte Betriebsverhältnisse von Elektronenröhren, insbesondere Senderöhren größerer Leistung, verbieten die Verwendung von derartigen Kathoden.Such a directly heated cathode is known for example from DE-AS 24 15 384. From this DE-AS it is also known that for the production of cathodes which are heated directly and which have a metal film as an emission layer, for example tungsten carbide with a thorium film, tungsten wire is used as the carrier. By arranging the wires accordingly, at Transmitter tubes in mesh or needle shape, the required surface and mechanical strength is achieved. The structure of the cathodes inevitably results in an inhomogeneous cathode surface, which has an effect on the electrode system. There are also difficulties in manufacturing cathodes with narrow wire gaps. In the case of transmitter tubes with narrow grid-cathode distances and mesh cathodes, the different distances (outer wire and inner wire of the mesh cathode) have a disadvantageous effect on the electrical data of the electron tube.
Until now, cathodes with a homogeneous surface have only been known as oxide matrix or storage cathodes. Certain operating conditions of electron tubes, in particular transmitter tubes of higher power, prohibit the use of such cathodes.

Der Erfindung liegt daher die Aufgabe zugrunde, eine direkt geheizte Kathode zu schaffen, deren Träger nicht aus Draht besteht, so daß Inhomogenitäten auf der Kathodenoberfläche vermieden sind. Zur Lösung dieser Aufgabe wird bei einer direkt geheizten Kathode für Elektronenröhren, insbesondere Senderöhren, der eingangs genannten Art gemäß der Erfindung vorgeschlagen, daß der Hohlzylinder aus pyrolytischem Graphit besteht und mit einer dünnen Metallschicht als Emissionsschicht überzogen ist. Die dünne Metallschicht besteht dabei vorzugsweise aus Wolframkarbid und Thorium bzw. einem Thoriumoxid.The object of the invention is therefore to create a directly heated cathode, the carrier of which is not made of wire, so that inhomogeneities on the cathode surface are avoided. To solve this problem, it is proposed in a directly heated cathode for electron tubes, in particular transmitter tubes, of the type mentioned at the outset according to the invention that the hollow cylinder consists of pyrolytic graphite and is coated with a thin metal layer as an emission layer. The thin metal layer preferably consists of tungsten carbide and thorium or a thorium oxide.

Es ist an sich bekannt, Gitterelektroden für Elektronenröhren aus pyrolytischem Graphit herzustellen (man vgl. z.B. die DE-AS 1 194 988 bzw. die DE-AS 1 639 168). So können Zylinder, Platten, Ringe oder Scheiben aus pyrolytischem Graphit hergestellt werden. Dieses Graphit hat den Vorteil, daß es hohe Temperaturen verträgt und als Werkstoff für Vakuumteile gut geeignet ist.It is known per se to produce grid electrodes for electron tubes from pyrolytic graphite (cf. eg DE-AS 1 194 988 or DE-AS 1 639 168). For example, cylinders, plates, rings or disks can be made from pyrolytic graphite. This graphite has the advantage that it tolerates high temperatures and is well suited as a material for vacuum parts.

Die dünne Metallschicht (Kathodenschicht) vorzugsweise aus Wolframkarbid und Thorium bzw. Thoriumoxid läßt sich auf den aus pyrolytischem Graphit bestehenden Hohlhylinder der Kathode vorteilhaft durch folgende Verfahren aufbringen. Entweder wird als dünne Metallschicht Thorium-Wolfram-Pulver auf den Hohlzylinder kataphoretisch abgeschieden und anschließend aufgesintert oder es wird eine dünne, aus Thorium und Wolfram bestehende Metallschicht mit Hilfe eines Elektronenstrahls auf den Hohlzylinder aufgedampft. Ein weiteres zweckmäßiges Verfahren besteht darin, daß als dünne Metallschicht Thorium-Wolfram aus der Gasphase auf dem aus pyrolytischem Graphit bestehenden Hohlzylinder (Trägerkörper) abgeschieden wird.The thin metal layer (cathode layer), preferably made of tungsten carbide and thorium or thorium oxide, can advantageously be applied to the hollow cylinder of the cathode consisting of pyrolytic graphite by the following methods. Either thorium-tungsten powder is deposited cataphoretically as a thin metal layer onto the hollow cylinder and then sintered on, or a thin metal layer consisting of thorium and tungsten is vapor-deposited onto the hollow cylinder with the aid of an electron beam. Another expedient method consists in that thorium-tungsten is deposited as a thin metal layer from the gas phase on the hollow cylinder (carrier body) consisting of pyrolytic graphite.

Die erfindungsgemäßen direkt geheizten Kathoden haben insbesondere gegenüber Maschenkathoden folgende Vorteile. Die Standfestigkeit der Kathoden ist durch das pyrolytische Graphit bestimmt und im Vergleich zu Wolfram bei den Betriebstemperaturen sehr viel größer. Es können Flächenkathoden oder Strukturkathoden, je nach den Erfordernissen, hergestellt werden. Ein Ausbeulen des Kathodenzylinders durch eine Längenausdehnung beim Einschalten der Elektronenröhre tritt nicht mehr auf.The directly heated cathodes according to the invention have the following advantages, in particular over mesh cathodes. The stability of the cathodes is determined by the pyrolytic graphite and is much greater in comparison to tungsten at the operating temperatures. Depending on the requirements, flat cathodes or structured cathodes can be produced. Bulging of the cathode cylinder due to a length expansion when the electron tube is switched on no longer occurs.

An Hand der Figur der Zeichnung soll die Erfindung nachstehend mit weiteren Merkmalen erläuter werden. Teile, die nicht unbedingt zum Verständnis der Erfindung beitragen, sind darin unbezeichnet oder weggelassen.Based on the figure of the drawing, the invention will be explained below with further features. Parts that do not necessarily contribute to an understanding of the invention are not identified or are omitted.

Die Figur zeigt im Längsschnitt als Ausführungsbeispiel eine Sendetriode mit koaxial angeordneten zylindrischen Elektroden und Durchführungen. Dazu gehören im - einzelnen die zentrale direkt geheizte Kathode, die mit dem Durchführungsteller bzw. inneren Kathodenanschlußring 5 und dem Trägerrohr 6 (äußerer Kathodenanschluß) in Verbindung steht. Umschlossen ist der Hohlzylinder 1 der Kathode zunächst von der Gitterelektrode 3 und dann von der Anode 4 mit den zugehörigen Trägerrohren 7, 11. Das eigentliche Entladungsgefäß wird außer der als Außenanode ausgebildeten Anode 4 im wesentlichen vom Durchführungsfuß gebildet, der sich in üblicher MetallKeramik-Technik abwechselnd aus Metallträgerrohren bzw. -scheiben und Keramikringen zusammensetzt.The figure shows a longitudinal section as an exemplary embodiment of a transmitter triode with coaxially arranged cylindrical electrodes and bushings. These include - the central, directly heated cathode, which is connected to the feed-through plate or inner cathode connecting ring 5 and the support tube 6 (outer cathode connection). The hollow cylinder 1 of the cathode is initially surrounded by the grid electrode 3 and then by the anode 4 with the associated support tubes 7, 11. The actual discharge vessel is formed, in addition to the anode 4 designed as an external anode, essentially by the feed-through foot, which is used in conventional metal-ceramic technology alternately composed of metal support tubes or discs and ceramic rings.

Die auf dem Röhrenfuß befestigten Kathodenanschlüsse 5, 6 enden in jeweils einer Kathodenkappe 9 bzw. 12, an welche der eigentliche Hohlzylinder 1 der Kathode befestigt ist. Die jeweiligen Kathodenbefestigungen sind mit dem Bezugszeichen 2 versehen. An der Kathodenkappe 9 ist eine flexible Stromzuführung 8 befestigt, die von dem inneren Kathodenanschluß 5 zum Hohlzylinder 1 führt. Der Hohlzylinder 1 der Kathode besteht aus pyrolytischem Graphit und ist mit einer dünnen Metallschicht 10, vorzugsweise aus Wolframkarbid und Thorium, als Emissionsschicht überzogen.The cathode connections 5, 6 fastened on the tube foot each end in a cathode cap 9 or 12, to which the actual hollow cylinder 1 of the cathode is fastened. The respective cathode fastenings are provided with the reference number 2. A flexible power supply line 8 is attached to the cathode cap 9 and leads from the inner cathode connection 5 to the hollow cylinder 1. The hollow cylinder 1 of the cathode consists of pyrolytic graphite and is coated with a thin metal layer 10, preferably of tungsten carbide and thorium, as the emission layer.

Claims (5)

1. Direkt geheizte Kathode für Elektronenröhren, insbesondere Senderöhren, mit koaxialem Aufbau der Elektroden und deren Durchführungen, die einen Hohlzylinder aufweist, der an einem Ende an einer ringförmigen Kathodenzuführung und am anderen Ende an einer Kathodenkappe befestigt ist, die an einer koaxial in dem Hohlzylinder verlaufenden Stromzuführung gehaltert ist, dadurch gekennzeichnet , daß der Hohlzylinder (1) aus pyrolytischem Graphit besteht und mit einer dünnen Metallschicht (10) als Emissionsschicht überzogen ist.1. Directly heated cathode for electron tubes, in particular transmitter tubes, with a coaxial structure of the electrodes and their bushings, which has a hollow cylinder which is attached at one end to an annular cathode feed and at the other end to a cathode cap which is coaxial in the hollow cylinder current supply is held, characterized in that the hollow cylinder (1) consists of pyrolytic graphite and is coated with a thin metal layer (10) as an emission layer. 2. Direkt geheizte Kathode nach Anspruch 1, dadurch gekennzeichnet , daß die dünne Metallschicht (10) aus Wolframkarbid und Thorium besteht.2. Directly heated cathode according to claim 1, characterized in that the thin metal layer (10) consists of tungsten carbide and thorium. 3. Verfahren zum Herstellen einer direkt geheizten Kathode nach Anspruch 1 oder 2, dadurch gekennzeichnet, daß als dünne Metallschicht (10) Thorium-Wolfram-Pulver auf den Hohlzylinder (1) kataphoretisch abgeschieden und anschließend aufgesintert wird.3. A method for producing a directly heated cathode according to claim 1 or 2, characterized in that as a thin metal layer (10) thorium-tungsten powder on the hollow cylinder (1) is cataphoretically deposited and then sintered. 4. Verfahren zum Herstellen einer direkt geheizten Kathode nach Anspruch 1 oder 2, dadurch gekennzeichnet , daß eine dünne, aus Thorium und Wolfram bestehende Metallschicht (10) mit Hilfe eines Elektronenstrahls auf den Hohlzylinder (1) aufgedampft wird.4. A method for producing a directly heated cathode according to claim 1 or 2, characterized in that a thin metal layer (10) consisting of thorium and tungsten is vapor-deposited on the hollow cylinder (1) with the aid of an electron beam. 5. Verfahren zum Herstellen einer direkt geheizten Kathode nach Anspruch 1 oder 2, dadurch gekennzeichnet , daß als dünne Metallschicht (10) Thorium-Wolfram aus der Gasphase auf den Hohlzylinder (1) abgeschieden wird.5. A method for producing a directly heated cathode according to claim 1 or 2, characterized in that thorium-tungsten is deposited from the gas phase onto the hollow cylinder (1) as a thin metal layer (10).
EP19790102866 1978-08-31 1979-08-08 Directly heated cathode for an electron tube with coaxial electrode structure and method of making such a cathode Expired EP0010128B1 (en)

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Application Number Priority Date Filing Date Title
DE19782838020 DE2838020C3 (en) 1978-08-31 1978-08-31 Directly heated cathode for transmitter tubes with coaxial electrode structure
DE2838020 1978-08-31

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EP0010128A1 true EP0010128A1 (en) 1980-04-30
EP0010128B1 EP0010128B1 (en) 1983-02-16

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2498372A1 (en) * 1981-01-16 1982-07-23 Thomson Csf DIRECT HEATING CATHODE, METHOD FOR MANUFACTURING SAME, AND ELECTRONIC TUBE INCLUDING SUCH A CATHODE

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NL134258C (en) * 1968-04-29 1900-01-01
NL99689C (en) * 1956-11-14 1900-01-01
FR952894A (en) * 1946-09-06 1949-11-25 Int Standard Electric Corp Thoriated tungsten filaments for electronic discharge devices
DE1194988B (en) * 1962-03-02 1965-06-16 Thomson Houston Comp Francaise Grid electrode for electron tubes
DE2011615A1 (en) * 1969-03-17 1970-09-24 International Business Machines Corp., Armonk, N.Y. (V.St.A.) Glow-electric cathode
DE2415384A1 (en) * 1974-03-29 1975-10-02 Siemens Ag Transmission tube with coaxial electrodes - has strip cathode of cylindrical shape with emitter coated lid and strip-shaped envelope
DE2608746A1 (en) * 1975-03-04 1976-09-09 Thomson Csf PROCESS FOR PRE-HEATING THE THORIUM-CONTAINING TUNGSTEN CATODES OF ELECTRONIC TUBES OF HIGH POWER
NL7614122A (en) * 1975-12-24 1977-06-28 Jeol Ltd ELECTRON GUN.

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DE1614680C3 (en) * 1967-12-13 1973-10-11 Siemens Ag, 1000 Berlin U. 8000 Muenchen Electrical discharge vessel, in particular special HF power tubes
DE2625021C3 (en) * 1976-06-03 1979-06-07 Siemens Ag, 1000 Berlin Und 8000 Muenchen Electron tubes, in particular transmitter tubes

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Publication number Priority date Publication date Assignee Title
FR952894A (en) * 1946-09-06 1949-11-25 Int Standard Electric Corp Thoriated tungsten filaments for electronic discharge devices
NL99689C (en) * 1956-11-14 1900-01-01
FR1185981A (en) * 1956-11-14 1959-08-11 Philips Nv Method and device for applying a layer of emissive substances to the cathode bodies of thermionic cathodes with indirect heating
GB823900A (en) * 1956-11-14 1959-11-18 Philips Electrical Ind Ltd Improvements in or relating to methods and apparatus for applying electron-emissive coatings to cathode cores of indirectly heated thermionic cathodes
DE1194988B (en) * 1962-03-02 1965-06-16 Thomson Houston Comp Francaise Grid electrode for electron tubes
NL134258C (en) * 1968-04-29 1900-01-01
DE2011615A1 (en) * 1969-03-17 1970-09-24 International Business Machines Corp., Armonk, N.Y. (V.St.A.) Glow-electric cathode
FR2033868A5 (en) * 1969-03-17 1970-12-04 Ibm
GB1284034A (en) * 1969-03-17 1972-08-02 Ibm Cathode assembly
DE2415384A1 (en) * 1974-03-29 1975-10-02 Siemens Ag Transmission tube with coaxial electrodes - has strip cathode of cylindrical shape with emitter coated lid and strip-shaped envelope
DE2608746A1 (en) * 1975-03-04 1976-09-09 Thomson Csf PROCESS FOR PRE-HEATING THE THORIUM-CONTAINING TUNGSTEN CATODES OF ELECTRONIC TUBES OF HIGH POWER
FR2303372A1 (en) * 1975-03-04 1976-10-01 Thomson Csf Preheating tungsten cathodes in high power electron tubes - prevents overheating when full power is switched on
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DE2658316A1 (en) * 1975-12-24 1977-07-07 Jeol Ltd ELECTRON SOURCE
FR2336787A1 (en) * 1975-12-24 1977-07-22 Jeol Ltd ELECTRON CANNON

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2498372A1 (en) * 1981-01-16 1982-07-23 Thomson Csf DIRECT HEATING CATHODE, METHOD FOR MANUFACTURING SAME, AND ELECTRONIC TUBE INCLUDING SUCH A CATHODE
EP0056749A2 (en) * 1981-01-16 1982-07-28 Thomson-Csf Directly heated cathode and method of making it
EP0056749A3 (en) * 1981-01-16 1982-08-25 Thomson-Csf Directly heated cathode and method of making it

Also Published As

Publication number Publication date
DE2838020A1 (en) 1980-03-13
DE2838020C3 (en) 1987-06-19
EP0010128B1 (en) 1983-02-16
DE2838020B2 (en) 1981-04-02

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