US2543728A - Incandescible cathode - Google Patents

Incandescible cathode Download PDF

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Publication number
US2543728A
US2543728A US39264A US3926448A US2543728A US 2543728 A US2543728 A US 2543728A US 39264 A US39264 A US 39264A US 3926448 A US3926448 A US 3926448A US 2543728 A US2543728 A US 2543728A
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Prior art keywords
cavity
cathode
forming
supply
electron
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Expired - Lifetime
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US39264A
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English (en)
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Lemmens Hendricus Johannes
Loosjes Robert
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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
    • 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

Definitions

  • Our invention relates to an incandescible cathode having an internal cavity provided with a supply of electron-emitting material.
  • a cathode by spraying an alloy such as bariumaluminium onto an insulating or metallic support, providing on this alloy, likewise by the spraying process, a porous layer of a metal of the iron group or a metal of high melting temperature, and oxidising the last-mentioned layer superflcially or coating it with an alkaline-earth oxide.
  • an alloy such as bariumaluminium
  • a porous layer of a metal of the iron group or a metal of high melting temperature and oxidising the last-mentioned layer superflcially or coating it with an alkaline-earth oxide.
  • the aim of the invention is to provide a cathode of the kind described in the preamble which has a continuous high specific emission and at the same time a long period of life.
  • an electric discharge tube comprising a cathode having a supply of alkaline-earth metal compounds provided at the interior of the cathode
  • at least a part of the wall of the cathode which separates the supply of electron-emitting compounds from the discharge tube consists of a homogeneously porous sintered body of one or more of the refractory metals tungsten, molybdenum, tantalum, hafnium and niobium, the pores in the porous body being the largest apertures that are provided in the said wall.
  • the cathode of such a discharge tube may, without objection, be operated at higher temperatures (from 1200 to 1400 C.) since as a result of the porosity of the body a small amount only of electron-emitting compounds with free metal is admitted to the surface so that a very thin layer is present thereon.
  • the porosity of the wall portion that is required to pass the electronemitting compounds is dependent on the working temperature of the cathode, the nature of the electron-emitting compounds, and the nature of the porous body itself.
  • the specific emission may become very high owing to the permissible higher temperatures and the cathode may, without objection, be operated at 80% and upwards of the saturation emission owing to the uniform coating on its surface. This value is from 5 to 10% at the most in the case of an ordinary carbonate cathode.
  • Figure 1 is a side view in section of a cathode according to the invention
  • Fig. 2 is a side view in section of a cathode according to another embodiment of the invention.
  • Fig. 3 is a side view in section of a tubular type cathode according to the invention.
  • reference numeral l designates a porous tungsten cup-shaped member which is obtained by sintering powdery tungsten at a temperature of from 1600 to 2200 C. to form a long rod, from which the cup-shaped body having a wall thickness of 0.5 mm. is turned out.
  • the body I is 5 mm. in diameter and is partly filled with barium-strontium carbonate 2.
  • a molybdenum disc 3, which exactly fits in the cupshaped body I, is provided behind the bariumstrontium carbonate.
  • the cup-shaped body i is provided in the foremost cylindrical cavity of the molybdenum body 4, turned in one piece, in such manner that a minimum number of gaps subsist.
  • cup-shaped body i is rigidly pressed against a partition 5 forming part of body 4.
  • a filament 6 is provided in the hindmost cavity of the said body,
  • the cathode structure shown in Figure 2 comprises a cup-shaped body I which is similar to member I and is of homogeneously-porous sintered tungsten.
  • a cup 8 of molybdenum fits tightly into the open end of body I to form therewith a cavity containing a supply of bariumstrontium carbonate 2.
  • a cup 9 of molybdenum fits tightly over the outside of body I and forms with cup 8 a space in which is located a filament i having a diameter of about 10 mms. and supported by lead-in wires which pass through cap 9 and are insulated therefrom.
  • the cylindrical cathode structure shown in Fig. 3 which is particularly suited for use in a cavity-resonator magnetron for generating centimeter waves, comprises a tubular homogeneously-porous sintered body H, which similarly to bodies I and 1 is made of tungsten, has a wall thickness of about 0.5 mm. and a diameter of about mms.
  • a cylindrical member [2 having a flanged end fits into the body II and a second cylindrical member I3 having a flanged end fits into the cylindrical member l2,
  • Members I2 and I3 form with body ll an annular cavity in which is located a supply of barium-strontium carbonate 2.
  • Members l2 and I3 are held in position by rings l4 whose edges are flanged over protuberances on the end of body ll so as to form a tight fit.
  • a filament I5 Located within the central cavity formed by cylindrical members l2 and i3 is a filament I5 supported by lead-in wires passing through discs iii of ceramic material secured to cylindrical members I2 and [3.
  • the carbonates of the above-described cathodes are dissociated in the usual manner after the cathode has been provided in an electric discharge tube, a great current may be obtained from the cathode surface, constituted by the front surface of I, I or II a short time subsequent to the heating of the cathode to a temperature of about 1200 C.
  • a continuous load of 1 amp/cm. does not bring about variation in the current-voltage characteristic curve, in contradistinction to cathodes of the conventional type. Provisional tests in which the discharge tubes had to be taken out of use for other reasons (burned filament, shortcircuit between the electrodes) yielded periods of life of 600 hours at 5 amps/cm. and 300 hours at 20 amps/cm. without involving variation in the characteristic curve.
  • sintered body as used herein and in the claims is to be understood to mean a body which is formed by heating finely-divided refractory metal at a temperature of at least 1600 C.
  • a cathode comprising a structure forming an internal cavity, the portion of the structure surrounding said cavity consisting of refractory metal, a supply of an alkaline-earth metal compound in said cavity, and a homogeneouslyporous sintered body of refractory metal forming the emissive part of the wall of said structure, said structure being tightly closed with the pores of said body forming the largest apertures connecting the cavity to the outside of the structure.
  • a cathode comprising a structure formin an internal cavity, the portion of the structure surrounding said cavity consisting of refractory metal, a supply of alkaline-earth metal oxide in said cavity, and a homogeneously-porous sintered body of refractory metal forming the emissive part of the wall of said structure, said structure being tightly closed with the pores of said body forming the largest apertures connecting the cavity to the outside of the structure.
  • a cathode comprising a structure forming an internal cavity, the portion of the structure surrounding said cavity consisting of refractory metal, a supply of barium-strontium oxide in said cavity, and a homogeneously-porous sintered body of refractory metal forming the emissive part of the wall of said structure, said structure being tightly closed with the pores of said body forming the largest apertures connecting the cavity to the outside of the structure.
  • a cathode comprising a structure forming an internal cavity, the portion of the structure surrounding said cavity consisting of metal having a melting point above about 1200 C., a sunply of an alkaline-earth metal compound in said cavity and a homogeneously-porous sintered body of tungsten forming the emissive part of the wall of said structure, said structure being tightly closed with the pores of said body forming the largest apertures connecting the cavity to the outside of the structure.
  • a cathode comprising a structure forming an internal cavity, the portion of said structure surrounding said cavity consisting of metal having a melting point above about 1200 C., a supply of an alkaline-earth metal compound in said cavity and a homogeneously-porous sintered body of molybdenum forming the emissive part of the wall of said structure, said structure being tightly closed with the pores of said body forming the largest apertures connecting the cavity of the outside of the structure.
  • a cathode comprising a structure forming an internal cavity, the portion of the structure surrounding said cavity consisting of metal having a melting point above about 1200 C., a supply of an alkaline-earth metal compound in said cavity and a homogeneously-porous sintered body of tantalum forming the emissive part of the wall of said structure, said structure being tightly closed with the pores of said body forming the largest apertures connecting the cavity to the outside of the structure.
  • a cathode comprising a structure forming an internal cavity, the portion of the structure surrounding said cavity consisting of metal having a melting point above about 1200 C., a supply of an alkaline-earth metal compound in said cavity and a homogeneously-porous sintered body of hafnium forming the emissive part 01' the wall of said structure, said structure being tightly closed with the pores of said body forming the largest apertures connecting the cavity to the outside of the structure.
  • a cathode comprising a structure forming an internal cavity, the portion of the structure surrounding said cavity consisting of metal having a melting point above about 1200 C., a supply of an alkaline-earth metal compound in said cavity and a homogeneously-porous sintered body of niobium forming the emissive part of the wall of said structure, said structure being tightly closed with the pores of said body forming the largest apertures connecting the cavity to the outside of the structure.
  • a cathode comprising a structure including a homogeneously-porous sintered body forming the emissive part of the wall of said structure and composed of refractory metal, and a member having a cup-shaped portion forming an internal cavity with said body, the portion of said structure surrounding said cavity consisting of metal having a melting point above about 1200 C., and a supply of an alkaline-earth metal compound in said cavity, said structure being tightly closed with the pores of said body forming the largest apertures connecting the cavity to the outside 01 the structure.
  • a cathode comprising a structure including a homogeneously-porous sintered body of tungsten forming the emissive part of the wall of said structure, and a member having a cup-shaped portion of molybdenum forming an internal cavity with said body, the portion of said structure surrounding said cavity consisting of metal having a melting point above about 1200 C., and a supply of an alkaline-earth metal compound in said cavity, said structure being tightly closed with the pores of said body forming the largest apertures connecting the cavity to the outside of the structure.
  • a cathode comprising a structure including a homogeneously-porous sintered body of tungsten forming the emissive part of the wall of said structure, and a member having a portion of molybdenum forming an internal cavity with said body, the portion of said structure surrounding said cavity consisting of metal having a melting point above about 1200 C., and a supply of barium-strontium oxide in said cavity, said structure being tightly closed with the pores of said body forming the largest apertures connecting the cavity to the outside of the structure.
  • a cathode comprising a structure including a tubular homogeneously-porous sintered body forming the emissive part of the wall of the structure and composed of refractory metal, a tubular member disposed within said sintered body and means closing the ends of said body and member to form an internal cavity, the portion of said structure surrounding said cavity consisting of metal having a melting point above about 1200 C., and-a supply of an alkalineearth metal compound in said cavity, said structure being tightly closed with the pores of said sintered body forming the largest apertures connecting the cavity to the outside of the structure.
  • An incandescible cathode comprising a structure forming an internal cavity, a supply of an electron-emissive material within said cavity, means to heat said material, and a homogeneously-porous sintered body of tungsten forming part of the wall of said body, the pores of said body being the largest apertures connecting the cavity to the outside of the structure and having an inner surface area of about 8,000 to 10,000 square centimeters per cubic centimeter, said tungsten body having a density equal to about of the maximum value.

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  • Solid Thermionic Cathode (AREA)
US39264A 1947-11-26 1948-07-17 Incandescible cathode Expired - Lifetime US2543728A (en)

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NL272699X 1947-11-26

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US (1) US2543728A (US06650917-20031118-M00005.png)
BE (1) BE486002A (US06650917-20031118-M00005.png)
CH (3) CH274440A (US06650917-20031118-M00005.png)
FR (1) FR975422A (US06650917-20031118-M00005.png)
GB (1) GB641581A (US06650917-20031118-M00005.png)
NL (1) NL69486C (US06650917-20031118-M00005.png)

Cited By (37)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2671868A (en) * 1950-04-11 1954-03-09 Texas Co Gamma ray detector
US2673277A (en) * 1949-10-25 1954-03-23 Hartford Nat Bank & Trust Co Incandescible cathode and method of making the same
US2677778A (en) * 1952-03-31 1954-05-04 Atomic Energy Commission Linear cathode
US2698913A (en) * 1951-11-29 1955-01-04 Philips Corp Cathode structure
US2700118A (en) * 1951-11-29 1955-01-18 Philips Corp Incandescible cathode
US2716716A (en) * 1951-11-29 1955-08-30 Philips Corp Cathode containing a supply of an electron-emissive material
US2718607A (en) * 1950-12-27 1955-09-20 Siemens Ag Dispenser-type cathode for electrical discharge tube
US2722626A (en) * 1953-02-16 1955-11-01 Philips Corp Thermionic cathode
US2737607A (en) * 1951-07-17 1956-03-06 Hartford Nat Bank & Trust Co Incandescible cathode
US2741717A (en) * 1951-06-14 1956-04-10 Siemens Ag Dispenser type cathode having gettercoated parts
US2750527A (en) * 1951-11-19 1956-06-12 Siemens Ag Cathode for electrical discharge device
US2761993A (en) * 1951-06-09 1956-09-04 Siemens Ag Cathodes for electrical discharge devices
US2774916A (en) * 1951-06-09 1956-12-18 Siemens Ag Cathodes for electrical discharge devices
US2777086A (en) * 1952-07-26 1957-01-08 Westinghouse Electric Corp Cathode
US2783407A (en) * 1952-06-28 1957-02-26 Vierkotter Paul Source of light
US2798182A (en) * 1951-07-12 1957-07-02 Siemens Ag Dispenser cathode having heater embedded in densely sintered receptacle wall
US2808530A (en) * 1951-04-18 1957-10-01 Siemens Ag Cathode for electrical discharge devices
US2814754A (en) * 1952-08-28 1957-11-26 Raytheon Mfg Co Indirectly-heated cathodes
US2817784A (en) * 1951-01-31 1957-12-24 Siemens Ag Cathode for use in electrical discharge devices
US2830218A (en) * 1953-09-24 1958-04-08 Gen Electric Dispenser cathodes and methods of making them
US2848644A (en) * 1953-01-19 1958-08-19 Philips Corp Thermionic cathode
US2867742A (en) * 1953-02-26 1959-01-06 Philips Corp Dispenser cathode
US2899592A (en) * 1953-11-18 1959-08-11 coppola
US2902621A (en) * 1953-03-04 1959-09-01 Egyesuelt Izzolampa Supply cathode
US2902620A (en) * 1953-03-04 1959-09-01 Egyesuelt Izzolampa Supply cathode
US2925514A (en) * 1952-04-09 1960-02-16 Philips Corp Thermionic cathode
US2928013A (en) * 1954-12-23 1960-03-08 Siemens Ag Electrical discharge device
US2931934A (en) * 1955-02-05 1960-04-05 Egyesuelt Izzolampa Indirectly heated supply cathode
US2988666A (en) * 1953-12-22 1961-06-13 Philips Corp Cylindrical dispenser cathode for magnetrons
US3010046A (en) * 1952-02-26 1961-11-21 Westinghouse Electric Corp Cathode structure
US3010826A (en) * 1951-03-22 1961-11-28 Philips Corp Method of making dispenser type cathodes
US3076915A (en) * 1954-12-24 1963-02-05 Egyesuelt Izzolampa Cathode assembly and method of making same
US3113236A (en) * 1959-06-23 1963-12-03 Philips Corp Oxide dispenser type cathode
US3251641A (en) * 1962-03-27 1966-05-17 Rca Corp Electron tube and method of making the same
US5022883A (en) * 1990-11-06 1991-06-11 The United States Of America As Represented By The Secretary Of The Army Method of making a long life high current density cathode from aluminum oxide and tungsten oxide powders
US5293410A (en) * 1991-11-27 1994-03-08 Schlumberger Technology Corporation Neutron generator
US20030025435A1 (en) * 1999-11-24 2003-02-06 Vancil Bernard K. Reservoir dispenser cathode and method of manufacture

Families Citing this family (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1075747B (de) * 1960-02-18 Deutsche Elektronik G.m.b.H., Berlin-Wilmersdorf Zylindrische Vorratskathode für Magnetfeldröhren
DE972442C (de) * 1952-05-27 1959-07-23 Siemens Ag Halterung fuer eine Kathode fuer elektrische Entladungsgefaesse
DE1060499B (de) * 1952-05-31 1959-07-02 Egyesuelt Izzolampa Vorratskathode mit in einem getrennten Raum befindlichen aktiven Stoffen und Reduziermitteln
DE965431C (de) * 1952-07-18 1957-06-06 Egyesuelt Izzolampa Gluehkathode mit einem durch einen poroesen Wolframsinterkoerper abgeschlossenen Raum, in dem mindestens ein Alkalimetall enthalten ist
DE954898C (de) * 1952-07-23 1956-12-27 Siemens Ag Kathode mit einem Emissionsstoffvorrat fuer elektrische Entladungsgefaesse
DE1052578B (de) * 1953-06-18 1959-03-12 Siemens Ag Verfahren zur Herstellung einer Oxydkathode mit einer auf die Oberflaeche des Kathodenkoerpers aufgesinterten, porigen Metallschicht
NL108979C (US06650917-20031118-M00005.png) * 1953-12-17
FR1283895A (fr) * 1960-12-21 1962-02-09 Csf Structure de cathode froide
DE1275692B (de) * 1963-10-14 1968-08-22 Litton Industries Inc Verfahren zur Herstellung einer Vorratskathode fuer Elektronenroehren
JPS58100329A (ja) * 1981-12-11 1983-06-15 Toshiba Corp 電子管用陰極構体

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2121589A (en) * 1934-06-28 1938-06-21 Westinghouse Electric & Mfg Co Emissive incandescent cathode

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2121589A (en) * 1934-06-28 1938-06-21 Westinghouse Electric & Mfg Co Emissive incandescent cathode

Cited By (37)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2673277A (en) * 1949-10-25 1954-03-23 Hartford Nat Bank & Trust Co Incandescible cathode and method of making the same
US2671868A (en) * 1950-04-11 1954-03-09 Texas Co Gamma ray detector
US2718607A (en) * 1950-12-27 1955-09-20 Siemens Ag Dispenser-type cathode for electrical discharge tube
US2817784A (en) * 1951-01-31 1957-12-24 Siemens Ag Cathode for use in electrical discharge devices
US3010826A (en) * 1951-03-22 1961-11-28 Philips Corp Method of making dispenser type cathodes
US2808530A (en) * 1951-04-18 1957-10-01 Siemens Ag Cathode for electrical discharge devices
US2774916A (en) * 1951-06-09 1956-12-18 Siemens Ag Cathodes for electrical discharge devices
US2761993A (en) * 1951-06-09 1956-09-04 Siemens Ag Cathodes for electrical discharge devices
US2741717A (en) * 1951-06-14 1956-04-10 Siemens Ag Dispenser type cathode having gettercoated parts
US2798182A (en) * 1951-07-12 1957-07-02 Siemens Ag Dispenser cathode having heater embedded in densely sintered receptacle wall
US2737607A (en) * 1951-07-17 1956-03-06 Hartford Nat Bank & Trust Co Incandescible cathode
US2750527A (en) * 1951-11-19 1956-06-12 Siemens Ag Cathode for electrical discharge device
US2700118A (en) * 1951-11-29 1955-01-18 Philips Corp Incandescible cathode
US2716716A (en) * 1951-11-29 1955-08-30 Philips Corp Cathode containing a supply of an electron-emissive material
US2698913A (en) * 1951-11-29 1955-01-04 Philips Corp Cathode structure
US3010046A (en) * 1952-02-26 1961-11-21 Westinghouse Electric Corp Cathode structure
US2677778A (en) * 1952-03-31 1954-05-04 Atomic Energy Commission Linear cathode
US2925514A (en) * 1952-04-09 1960-02-16 Philips Corp Thermionic cathode
US2783407A (en) * 1952-06-28 1957-02-26 Vierkotter Paul Source of light
US2777086A (en) * 1952-07-26 1957-01-08 Westinghouse Electric Corp Cathode
US2814754A (en) * 1952-08-28 1957-11-26 Raytheon Mfg Co Indirectly-heated cathodes
US2848644A (en) * 1953-01-19 1958-08-19 Philips Corp Thermionic cathode
US2722626A (en) * 1953-02-16 1955-11-01 Philips Corp Thermionic cathode
US2867742A (en) * 1953-02-26 1959-01-06 Philips Corp Dispenser cathode
US2902621A (en) * 1953-03-04 1959-09-01 Egyesuelt Izzolampa Supply cathode
US2902620A (en) * 1953-03-04 1959-09-01 Egyesuelt Izzolampa Supply cathode
US2830218A (en) * 1953-09-24 1958-04-08 Gen Electric Dispenser cathodes and methods of making them
US2899592A (en) * 1953-11-18 1959-08-11 coppola
US2988666A (en) * 1953-12-22 1961-06-13 Philips Corp Cylindrical dispenser cathode for magnetrons
US2928013A (en) * 1954-12-23 1960-03-08 Siemens Ag Electrical discharge device
US3076915A (en) * 1954-12-24 1963-02-05 Egyesuelt Izzolampa Cathode assembly and method of making same
US2931934A (en) * 1955-02-05 1960-04-05 Egyesuelt Izzolampa Indirectly heated supply cathode
US3113236A (en) * 1959-06-23 1963-12-03 Philips Corp Oxide dispenser type cathode
US3251641A (en) * 1962-03-27 1966-05-17 Rca Corp Electron tube and method of making the same
US5022883A (en) * 1990-11-06 1991-06-11 The United States Of America As Represented By The Secretary Of The Army Method of making a long life high current density cathode from aluminum oxide and tungsten oxide powders
US5293410A (en) * 1991-11-27 1994-03-08 Schlumberger Technology Corporation Neutron generator
US20030025435A1 (en) * 1999-11-24 2003-02-06 Vancil Bernard K. Reservoir dispenser cathode and method of manufacture

Also Published As

Publication number Publication date
FR975422A (fr) 1951-03-05
CH274441A (de) 1951-03-31
NL69486C (US06650917-20031118-M00005.png)
GB641581A (en) 1950-08-16
CH274440A (de) 1951-03-31
CH272699A (de) 1950-12-31
BE486002A (US06650917-20031118-M00005.png)

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