US2614942A - Thermionic cathode - Google Patents

Thermionic cathode Download PDF

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Publication number
US2614942A
US2614942A US112246A US11224649A US2614942A US 2614942 A US2614942 A US 2614942A US 112246 A US112246 A US 112246A US 11224649 A US11224649 A US 11224649A US 2614942 A US2614942 A US 2614942A
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United States
Prior art keywords
cathode
thorium oxide
mixture
sintered
refractory metal
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Expired - Lifetime
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US112246A
Inventor
Loosjes Robert
Antonius Josephus V Genuchten
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Hartford National Bank and Trust Co
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Hartford National Bank and Trust Co
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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
    • H01J9/042—Manufacture, activation of the emissive part
    • 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
    • H01J61/00—Gas-discharge or vapour-discharge lamps
    • H01J61/02—Details
    • H01J61/04—Electrodes; Screens; Shields
    • H01J61/06—Main electrodes
    • H01J61/073—Main electrodes for high-pressure discharge lamps
    • H01J61/0735—Main electrodes for high-pressure discharge lamps characterised by the material of the electrode
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00—Stock material or miscellaneous articles
    • Y10T428/29—Coated or structually defined flake, particle, cell, strand, strand portion, rod, filament, macroscopic fiber or mass thereof
    • Y10T428/2913—Rod, strand, filament or fiber
    • Y10T428/2933—Coated or with bond, impregnation or core
    • Y10T428/294—Coated or with bond, impregnation or core including metal or compound thereof [excluding glass, ceramic and asbestos]
    • Y10T428/2958—Metal or metal compound in coating
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00—Stock material or miscellaneous articles
    • Y10T428/29—Coated or structually defined flake, particle, cell, strand, strand portion, rod, filament, macroscopic fiber or mass thereof
    • Y10T428/2913—Rod, strand, filament or fiber
    • Y10T428/298—Physical dimension

Definitions

  • This invention relates to cathodes the emission properties of which are determined by thorium oxide, the cathode body consisting of a sintered mixture of thorium oxide and a refractory metal such as tungsten.
  • the aforementioned type of cathodes have already been used in gaseous discharge lamps in which they are heated by the discharge. If the mixture is pressed at a suiciently high pressure and sintered at a sufficiently high temperature, the cathode body has great mechanical rigidity.
  • a disadvantage is that the oxide-metal mixture is black so that the radiation has a comparatively high value. Furthermore, the specific emission is comparatively low.
  • the object of the invention is to provide an improvement in the above-mentioned cathode.
  • a cathode the emission properties of which are determined by thorium oxide, and the cathode body of which consists of a mixture of thorium oxide and a refractory metal such as tungsten which mixture is pressed at high pressure and subsequently sintered, is covered with a thin layer of thorium oxide which is secured by sintering to the cathode body. Since thorium oxide is white, the thermal radiation is comparatively small, whilst the specific electron emission of thorium oxide is materially higher than that of the mixture of thorium-oxide metal. Activation of the cathode is not required, since the cathode is capable of emitting electrons directly after incorporation in a tube.
  • an electric discharge tube l comprises an envelope 2 enclosing a cathode 3, a control grid 4 and an anode 5.
  • the cathode 3 comprises a body of a sintered mixture of thorium oxide and a refractory metal, e. g., tungsten, which body ⁇ has a thin layer 6 of thorium oxide sintered thereto.
  • a refractory metal e. g., tungsten
  • a mixture consisting of equal amounts by weight of thorium oxide and of tungsten is pressed at high pressure to form a cylindrical vtemperatures up to 2300 C.
  • Theheating of the cathode takes place evenly due to the intimate mixture of the tungsten and the thorium oxide.
  • the specific emission may be up to 50 amps/cm.2 at a temperature of 2200 K. The period of life is Very long.
  • a cathode comprising a body composed of a sintered mixture of thorium oxide and a refractory metal, and a discrete thin layer of given thickness of thorium oxide covering said mixture of thorium oxide and refractory metal and sin tered to said body.
  • a cathode comprising a body composed of a sintered mixture of thorium oxide and tungsten, and a discretethin layer of given thickness of thorium oxide covering said mixture of thorium oxide and refractory metal and sintered to said ROBERT LOOSJES.

Description

Patented Oct. 21, 1952 THERMIONIC CATHODE Robert Loosjes and Antonius Josephus v.
Genuchten, Eindhoven, Netherlands, assigncrs to Hartford National Bank and Trust Company, Hartford, Conn., as trustee Application August 25, 1949, Serial No. 112,246 In the Netherlands September 11i, 1948 3 Claims. l
This invention relates to cathodes the emission properties of which are determined by thorium oxide, the cathode body consisting of a sintered mixture of thorium oxide and a refractory metal such as tungsten.
The aforementioned type of cathodes have already been used in gaseous discharge lamps in which they are heated by the discharge. If the mixture is pressed at a suiciently high pressure and sintered at a sufficiently high temperature, the cathode body has great mechanical rigidity. A disadvantage is that the oxide-metal mixture is black so that the radiation has a comparatively high value. Furthermore, the specific emission is comparatively low.
The object of the invention is to provide an improvement in the above-mentioned cathode.
According to the invention, a cathode the emission properties of which are determined by thorium oxide, and the cathode body of which consists of a mixture of thorium oxide and a refractory metal such as tungsten which mixture is pressed at high pressure and subsequently sintered, is covered with a thin layer of thorium oxide which is secured by sintering to the cathode body. Since thorium oxide is white, the thermal radiation is comparatively small, whilst the specific electron emission of thorium oxide is materially higher than that of the mixture of thorium-oxide metal. Activation of the cathode is not required, since the cathode is capable of emitting electrons directly after incorporation in a tube. The invention will now be described with reference to the accompanying drawing in which the sole figure is a view, in cross-section, of an electric discharge tube comprising one form of cathode in accordance with the invention.
Referring to the figure, an electric discharge tube l comprises an envelope 2 enclosing a cathode 3, a control grid 4 and an anode 5. The cathode 3 comprises a body of a sintered mixture of thorium oxide and a refractory metal, e. g., tungsten, which body `has a thin layer 6 of thorium oxide sintered thereto. The composition of the cathode will now be explained more fully by reference to the following example.
A mixture consisting of equal amounts by weight of thorium oxide and of tungsten is pressed at high pressure to form a cylindrical vtemperatures up to 2300 C. Theheating of the cathode takes place evenly due to the intimate mixture of the tungsten and the thorium oxide. If the cathode is operated by pulses, the specific emission may be up to 50 amps/cm.2 at a temperature of 2200 K. The period of life is Very long.
What we claim is: i
1. A cathode comprising a body composed of a sintered mixture of thorium oxide and a refractory metal, and a discrete thin layer of given thickness of thorium oxide covering said mixture of thorium oxide and refractory metal and sin tered to said body.
2. A cathode comprising a body composed of a sintered mixture of thorium oxide and tungsten, and a discretethin layer of given thickness of thorium oxide covering said mixture of thorium oxide and refractory metal and sintered to said ROBERT LOOSJES. ANTONIUS J OSEPHUS V. GENUCHTEN.
REFERENCES CITED The following references are of record in the le of this patent:
UNITED STATES PATENTS Number Name Date 2,339,392 Garner Jan. l8rJ 1944 2,477,601
Hanson Aug. 2, 1949

Claims (1)

1. A CATHODE COMPRISING A BODY COMPOSED OF A SINTERED MIXTURE OF THORIUM OXIDE AND A REFRACTORY METAL, AND A DISCRETE THIN LAYER OF GIVEN THICKNESS OF THORIUM OXIDE COVERING SAID MIXTURE OF THORIUM OXIDE AND REFRACTORY METAL AND SINTERED TO SAID BODY.
US112246A 1948-09-14 1949-08-25 Thermionic cathode Expired - Lifetime US2614942A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
NL278121X 1948-09-14

Publications (1)

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US2614942A true US2614942A (en) 1952-10-21

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Country Status (7)

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US (1) US2614942A (en)
BE (1) BE491070A (en)
CH (1) CH278121A (en)
DE (1) DE813573C (en)
FR (1) FR995225A (en)
GB (1) GB666053A (en)
NL (1) NL70864C (en)

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2717975A (en) * 1951-03-30 1955-09-13 Wihtol Weltis Cathodes for electron tubes
US2845515A (en) * 1953-03-12 1958-07-29 Raytheon Mfg Co Semimetallic resistive filaments
US2847328A (en) * 1957-03-04 1958-08-12 James E Cline Method of making thorium oxide cathodes
US3558966A (en) * 1967-03-01 1971-01-26 Semicon Associates Inc Directly heated dispenser cathode
US3973155A (en) * 1975-01-31 1976-08-03 Westinghouse Electric Corporation Incandescent source of visible radiations
US4333035A (en) * 1979-05-01 1982-06-01 Woodland International Corporation Areal array of tubular electron sources
US4438557A (en) * 1979-05-01 1984-03-27 Woodland International Corporation Method of using an areal array of tubular electron sources
WO2009045605A2 (en) * 2007-09-28 2009-04-09 General Electric Company Thermo-optically functional compositions, systems and methods of making

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1009727B (en) * 1953-01-10 1957-06-06 Deutsche Elektronik Gmbh Process for producing solid, well-adhering emission layers made of thorium oxide on a carrier metal made of tungsten or molybdenum
US2881512A (en) * 1954-06-16 1959-04-14 Cie Generale De Telegraphite S Composition for sintered barium cathodes
DE1080700B (en) * 1958-05-17 1960-04-28 Deutsche Elektronik Gmbh Process for the production of an indirectly heated cathode, in particular for magnetrons with high oscillating power, and cathode produced according to this process

Citations (2)

* 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
US2477601A (en) * 1947-06-11 1949-08-02 Raytheon Mfg Co Directly heated cathode

Patent Citations (2)

* 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
US2477601A (en) * 1947-06-11 1949-08-02 Raytheon Mfg Co Directly heated cathode

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2717975A (en) * 1951-03-30 1955-09-13 Wihtol Weltis Cathodes for electron tubes
US2845515A (en) * 1953-03-12 1958-07-29 Raytheon Mfg Co Semimetallic resistive filaments
US2847328A (en) * 1957-03-04 1958-08-12 James E Cline Method of making thorium oxide cathodes
US3558966A (en) * 1967-03-01 1971-01-26 Semicon Associates Inc Directly heated dispenser cathode
US3973155A (en) * 1975-01-31 1976-08-03 Westinghouse Electric Corporation Incandescent source of visible radiations
US4333035A (en) * 1979-05-01 1982-06-01 Woodland International Corporation Areal array of tubular electron sources
US4438557A (en) * 1979-05-01 1984-03-27 Woodland International Corporation Method of using an areal array of tubular electron sources
WO2009045605A2 (en) * 2007-09-28 2009-04-09 General Electric Company Thermo-optically functional compositions, systems and methods of making
WO2009045605A3 (en) * 2007-09-28 2010-03-18 General Electric Company Thermo-optically functional compositions, systems and methods of making

Also Published As

Publication number Publication date
FR995225A (en) 1951-11-29
GB666053A (en) 1952-02-06
DE813573C (en) 1951-09-13
BE491070A (en)
NL70864C (en)
CH278121A (en) 1951-09-30

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