US2698913A - Cathode structure - Google Patents

Cathode structure Download PDF

Info

Publication number
US2698913A
US2698913A US258875A US25887551A US2698913A US 2698913 A US2698913 A US 2698913A US 258875 A US258875 A US 258875A US 25887551 A US25887551 A US 25887551A US 2698913 A US2698913 A US 2698913A
Authority
US
United States
Prior art keywords
cathode
base
tube
cathode structure
caps
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US258875A
Other languages
English (en)
Inventor
George A Espersen
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
US Philips Corp
North American Philips Co Inc
Original Assignee
US Philips Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority to BE515835D priority Critical patent/BE515835A/xx
Application filed by US Philips Corp filed Critical US Philips Corp
Priority to US258875A priority patent/US2698913A/en
Priority to DEN6394A priority patent/DE927584C/de
Priority to ES0206486A priority patent/ES206486A1/es
Priority to GB29950/52A priority patent/GB716412A/en
Priority to FR1073995D priority patent/FR1073995A/fr
Priority to CH307780D priority patent/CH307780A/de
Application granted granted Critical
Publication of US2698913A publication Critical patent/US2698913A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • 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
    • H01J23/00—Details of transit-time tubes of the types covered by group H01J25/00
    • H01J23/02—Electrodes; Magnetic control means; Screens
    • H01J23/04—Cathodes
    • H01J23/05—Cathodes having a cylindrical emissive surface, e.g. cathodes for magnetrons
    • 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
    • Y10T428/12—All metal or with adjacent metals
    • Y10T428/12479—Porous [e.g., foamed, spongy, cracked, etc.]
    • 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
    • Y10T428/12—All metal or with adjacent metals
    • Y10T428/12493—Composite; i.e., plural, adjacent, spatially distinct metal components [e.g., layers, joint, etc.]
    • Y10T428/12535—Composite; i.e., plural, adjacent, spatially distinct metal components [e.g., layers, joint, etc.] with additional, spatially distinct nonmetal component
    • Y10T428/12576—Boride, carbide or nitride component
    • 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
    • Y10T428/12—All metal or with adjacent metals
    • Y10T428/12493—Composite; i.e., plural, adjacent, spatially distinct metal components [e.g., layers, joint, etc.]
    • Y10T428/12535—Composite; i.e., plural, adjacent, spatially distinct metal components [e.g., layers, joint, etc.] with additional, spatially distinct nonmetal component
    • Y10T428/12611—Oxide-containing component
    • 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
    • Y10T428/12—All metal or with adjacent metals
    • Y10T428/12493—Composite; i.e., plural, adjacent, spatially distinct metal components [e.g., layers, joint, etc.]
    • Y10T428/12771—Transition metal-base component
    • Y10T428/12806—Refractory [Group IVB, VB, or VIB] metal-base component
    • Y10T428/12826—Group VIB metal-base component
    • Y10T428/1284—W-base component

Definitions

  • the present invention relates to emissive cathode structures for electron discharge devices, and to a method of sealing said structure.
  • the principal object of this invention is to provide a cathode structure of high efficiency in which electrical leakage is minimized.
  • U. S. Patent 2,543,728 of Lemmen et al. there is disclosed a dispenser type cathode wherein a reservoir of electron emissive material is contained within a cavity in a tightly closed body of refractory metal having a porous wall portion, the pores of which form the largest passageways connecting the electron emissive material with the exterior of the cathode.
  • the present invention in a preferred form, makes use of a cathode structure of the dispenser type and further includes means effectively to seal the cathode structure. Provision is also made to reduce electrical leakage and to increase the emissive eficiency of the structure.
  • a cathode in accordance with the invention is inserted into a magnetron anode, but it is to be understood that the invention is not limited either to dispenser type cathodes or to the use of such cathodes in magnetrons.
  • the major elements of the magnetron are a cathode structure 10, an anode block 11 surroundng the cathode structure, and pole pieces 12 and 13 disposed at either end of the anode block for producing a magnetic field extending longitudinally through the anode and transversely with respect to the electron stream between the cathode and anode.
  • tubular metallic sleeve members 14 and 15 respeetively, which serve to support the cathode structure centi'ally within the anode block.
  • the sleeve members are held coaXially with respect to the pole pieces by means of insulating spacei's 16 and 17 formed, for example, of Ceramic material.
  • the anode block 11 is constructed to define a plurality of cavities circumferentially arranged about the cathode.
  • the cathode structure 10 is of the indirectly heated dispenser type and includes a porous tungsten cylinder 18 fitted on a molybdenum tube 19 provided with a constricted portion, thereby forming an annular cavity 20 in the area between the cylinder 18 and the tube 19.
  • This cavity is filled with electron emissive material 21 such as barium carbonate.
  • the nature of the emissive material may be of the type described in the above-mentioned Lemmens patent.
  • the porous tungsten cylinder is preferably fabricated in accordance with the teachings in the patent application of Levi, Serial No. 234,513, filed June 30, 1951.
  • a heater filament 22 coated with an insulating layer, such as aluminum oxide, to prevent shorting on the cathode.
  • the end leads 23 and 24 of the heater are extended through sleeve members 14 and 15.
  • the cathode assembly is completed by ring-shaped caps 26 and 27,
  • the seals between the caps, 26 and 27 and the ends of the tungsten tube 18 are of the diffusion type.
  • the washers 28 and 29 are formed of a metal having a low melting point relative to tungsten and molybdenum, such as platinum, titanium, zirconium, tantalum or thorium.
  • the technique of sealing is as follows: The washers are placed between the surfaces to be sealed and pressure is applied to the caps 26 and 27 by means, for example, of a clamp. Sufiicient pressure is applied to reduce the melting point of the Washer material so that diffusion into the walls of the metals to be sealed takes place. In a preferred method the cathode to be sealed is held in a press during the diffusion sealing process.
  • a moisture-free inert gas atmosphere is flowed about the cathode during the time that heat is applied to the entire assembly.
  • the pressure against the joints to be sealed grows greater due to thermal expansion of the cathode.
  • the increased pressure on the washers lowers the melting point thereof so that diffusion occurs.
  • a jig type fixture similar to a C-type clamp may be used, the clamp being made of invar or other low expanson coeificient material.
  • magnetron performance depends in large part upon the secondary emisson characteristic (8); that is to say the ratio of secondary to primary electron emisson. With Conventional cathodes of the dispenser type, this ratio is rather low, in the order of 1.5.
  • the outer surface of the tungten cylinder 18 is coated with material 30 yielding a high secondary emisson coefiicient such as oxides, nitrates, and borides of thorium, zirconum, columbium, cobalt and other elements withstanding temperatures higher than 1270 C. and which do not decompose or evaporate When Operating at this temperature.
  • the addition of any of the above-listed materials to the cathode surface will increase the value of the S by factors of from 2 to 20 fold, thus improving cathode efficiency.
  • conically-shaped metallic shields 31 and 32 which encircle the caps 26 and 27 of the cathode.
  • the use of a conical shield increases the length of the path from the cathode sleeve to the rim of the Shield, thereby lowering thetemperature of the shield, particularly at the rim, where un- Controlled emisson occurs, which emisson tends to raise the leakage current.
  • the cathode may be of the directly heated type in which the caps of the cathode act as elosures, the interior of the porous tungsten cylinder being filled With emissive material.
  • the cathode may be heated externally by bombardment from a primer cathode. lt is intended in the annexed claims to cover all such changes and modifications as fall within the true spirit of the invention.
  • a cathode assembly comprising a cylindrical body having electron emissive properties and constituted by a cylindrical metallic base, a porous metallic tube surrounding said base, said base having a constricted portion to form a cavity between said base and said tube, electron emissive material disposed in said cavity and a layer of material coating said body and having a relatively high secondary emisson coefi'icient, supporting members connected to the respective ends of said body, and a conically-shaped shield mounted on each-of-said members for reducing electrical leakage, the month of said shield facing said body.
  • a cathode assembly comprising a cylindrical body having electron emissive properties and including a cylindrical metallc base, a porous tungsten tube surroundng said base, the ends of said base projecting beyond the ends of said tube, said base having a constricted portion defining a cavity between said base and said tube, ring-shaped' caps mounted on the projecting ends of said base, a washer interposed between each cap and the adjacent end of the tube providing a ditfusion seal therebetween, electron emissive material disposed ⁇ in said cavity' anda layer of secondarily emissive material coated on: the: surface of said tube, supportingl members connected to the respective ends of said body, and a conicallyshapedf shi'eld' mounted on each of said members and encircling said caps.

Landscapes

  • Microwave Tubes (AREA)
  • Powder Metallurgy (AREA)
  • Solid Thermionic Cathode (AREA)
US258875A 1951-11-29 1951-11-29 Cathode structure Expired - Lifetime US2698913A (en)

Priority Applications (7)

Application Number Priority Date Filing Date Title
BE515835D BE515835A (en, 2012) 1951-11-29
US258875A US2698913A (en) 1951-11-29 1951-11-29 Cathode structure
DEN6394A DE927584C (de) 1951-11-29 1952-11-25 Zylindrische Vorratskathode, insbesondere fuer eine Magnetronroehre
ES0206486A ES206486A1 (es) 1951-11-29 1952-11-26 MEJORAS INTRODUCIDAS EN LOS CáTODOS CILiNDRICOS
GB29950/52A GB716412A (en) 1951-11-29 1952-11-26 Improvements in cylindrical cathodes
FR1073995D FR1073995A (fr) 1951-11-29 1952-11-27 Cathode cylindrique, du type à réserve, en particulier pour magnétrons
CH307780D CH307780A (de) 1951-11-29 1952-11-27 Zylinderkathode, insbesondere für eine Magnetronröhre.

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US258875A US2698913A (en) 1951-11-29 1951-11-29 Cathode structure

Publications (1)

Publication Number Publication Date
US2698913A true US2698913A (en) 1955-01-04

Family

ID=22982500

Family Applications (1)

Application Number Title Priority Date Filing Date
US258875A Expired - Lifetime US2698913A (en) 1951-11-29 1951-11-29 Cathode structure

Country Status (7)

Country Link
US (1) US2698913A (en, 2012)
BE (1) BE515835A (en, 2012)
CH (1) CH307780A (en, 2012)
DE (1) DE927584C (en, 2012)
ES (1) ES206486A1 (en, 2012)
FR (1) FR1073995A (en, 2012)
GB (1) GB716412A (en, 2012)

Cited By (20)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2813220A (en) * 1954-12-06 1957-11-12 Philips Corp Indirectly heated cathode
US2822302A (en) * 1956-01-16 1958-02-04 Radio Mfg Company Inc Non-emissive electrode
US2844868A (en) * 1954-06-01 1958-07-29 Sylvania Electric Prod Method of joining refractory metals
US2873217A (en) * 1954-05-20 1959-02-10 Ets Claude Paz & Silva Method for manufacturing a hollow electron-emissive electrode
US2882587A (en) * 1956-12-10 1959-04-21 Raytheon Mfg Co Brazing methods
US2956000A (en) * 1955-04-30 1960-10-11 Atomic Energy Authority Uk Fuel elements for nuclear reactor
US2957100A (en) * 1957-08-27 1960-10-18 Philips Corp Magnetron cathode structure
US2988666A (en) * 1953-12-22 1961-06-13 Philips Corp Cylindrical dispenser cathode for magnetrons
US3046444A (en) * 1959-04-28 1962-07-24 Raytheon Co Magnetrons
US3107422A (en) * 1961-05-16 1963-10-22 Bendix Corp Rhodium diffusion process for bonding and sealing of metallic parts
US3113236A (en) * 1959-06-23 1963-12-03 Philips Corp Oxide dispenser type cathode
US3132928A (en) * 1962-02-26 1964-05-12 Donald D Crooks Simultaneous brazing and corrosion protecting refractory metals
US3224071A (en) * 1960-03-14 1965-12-21 Philips Corp Brazing method for porous bodies
US3241230A (en) * 1962-10-12 1966-03-22 Roy I Batista Diffusion bonding of tungsten to tungsten
US3297901A (en) * 1964-06-05 1967-01-10 Litton Industries Inc Dispenser cathode for use in high power magnetron devices
US3410716A (en) * 1965-04-01 1968-11-12 Trw Inc Coating of refractory metals with metal modified oxides
US3431631A (en) * 1964-12-11 1969-03-11 Sylvania Electric Prod Refractory metal diffusion bonding
US3478415A (en) * 1965-08-27 1969-11-18 Johnson Matthey Co Ltd Bonding of metals or alloys
US3487536A (en) * 1966-02-24 1970-01-06 Teledyne Inc Method of forming a high temperature ceramic-to-metal seal
FR2522877A1 (fr) * 1982-03-05 1983-09-09 Philips Nv Procede pour la borination d'une cathode a reserve

Families Citing this family (2)

* 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
DE974430C (de) * 1952-10-04 1960-12-22 Telefunken Gmbh Geraeuscharme, mittelbar geheizte Schnellheizkathode fuer Elektronenroehren

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1267827A (en) * 1914-11-06 1918-05-28 Gen Electric Electric discharge device.
US2121589A (en) * 1934-06-28 1938-06-21 Westinghouse Electric & Mfg Co Emissive incandescent cathode
US2131204A (en) * 1936-01-15 1938-09-27 Siemens Ag Indirectly heated thermionic cathode
US2381012A (en) * 1942-01-03 1945-08-07 Raytheon Mfg Co Secondary electron discharge device
US2411601A (en) * 1941-09-30 1946-11-26 Raytheon Mfg Co Electronic discharge device
US2460119A (en) * 1944-09-23 1949-01-25 Gen Electric Magnetron
US2543728A (en) * 1947-11-26 1951-02-27 Hartford Nat Bank & Trust Co Incandescible cathode

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1267827A (en) * 1914-11-06 1918-05-28 Gen Electric Electric discharge device.
US2121589A (en) * 1934-06-28 1938-06-21 Westinghouse Electric & Mfg Co Emissive incandescent cathode
US2131204A (en) * 1936-01-15 1938-09-27 Siemens Ag Indirectly heated thermionic cathode
US2411601A (en) * 1941-09-30 1946-11-26 Raytheon Mfg Co Electronic discharge device
US2381012A (en) * 1942-01-03 1945-08-07 Raytheon Mfg Co Secondary electron discharge device
US2460119A (en) * 1944-09-23 1949-01-25 Gen Electric Magnetron
US2543728A (en) * 1947-11-26 1951-02-27 Hartford Nat Bank & Trust Co Incandescible cathode

Cited By (20)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2988666A (en) * 1953-12-22 1961-06-13 Philips Corp Cylindrical dispenser cathode for magnetrons
US2873217A (en) * 1954-05-20 1959-02-10 Ets Claude Paz & Silva Method for manufacturing a hollow electron-emissive electrode
US2844868A (en) * 1954-06-01 1958-07-29 Sylvania Electric Prod Method of joining refractory metals
US2813220A (en) * 1954-12-06 1957-11-12 Philips Corp Indirectly heated cathode
US2956000A (en) * 1955-04-30 1960-10-11 Atomic Energy Authority Uk Fuel elements for nuclear reactor
US2822302A (en) * 1956-01-16 1958-02-04 Radio Mfg Company Inc Non-emissive electrode
US2882587A (en) * 1956-12-10 1959-04-21 Raytheon Mfg Co Brazing methods
US2957100A (en) * 1957-08-27 1960-10-18 Philips Corp Magnetron cathode structure
US3046444A (en) * 1959-04-28 1962-07-24 Raytheon Co Magnetrons
US3113236A (en) * 1959-06-23 1963-12-03 Philips Corp Oxide dispenser type cathode
US3224071A (en) * 1960-03-14 1965-12-21 Philips Corp Brazing method for porous bodies
US3107422A (en) * 1961-05-16 1963-10-22 Bendix Corp Rhodium diffusion process for bonding and sealing of metallic parts
US3132928A (en) * 1962-02-26 1964-05-12 Donald D Crooks Simultaneous brazing and corrosion protecting refractory metals
US3241230A (en) * 1962-10-12 1966-03-22 Roy I Batista Diffusion bonding of tungsten to tungsten
US3297901A (en) * 1964-06-05 1967-01-10 Litton Industries Inc Dispenser cathode for use in high power magnetron devices
US3431631A (en) * 1964-12-11 1969-03-11 Sylvania Electric Prod Refractory metal diffusion bonding
US3410716A (en) * 1965-04-01 1968-11-12 Trw Inc Coating of refractory metals with metal modified oxides
US3478415A (en) * 1965-08-27 1969-11-18 Johnson Matthey Co Ltd Bonding of metals or alloys
US3487536A (en) * 1966-02-24 1970-01-06 Teledyne Inc Method of forming a high temperature ceramic-to-metal seal
FR2522877A1 (fr) * 1982-03-05 1983-09-09 Philips Nv Procede pour la borination d'une cathode a reserve

Also Published As

Publication number Publication date
ES206486A1 (es) 1953-01-16
BE515835A (en, 2012)
GB716412A (en) 1954-10-06
CH307780A (de) 1955-06-15
FR1073995A (fr) 1954-09-30
DE927584C (de) 1955-05-12

Similar Documents

Publication Publication Date Title
US2698913A (en) Cathode structure
US2543728A (en) Incandescible cathode
US3267308A (en) Thermionic energy converter
US3248591A (en) Discharge lamp electrode with integral cooling means
US3928783A (en) Thermionic cathode heated by electron bombardment
US2099531A (en) Electron discharge device
US2741717A (en) Dispenser type cathode having gettercoated parts
US2647216A (en) Dispenser cathode
US2489891A (en) Cesium electric discharge device
US4415829A (en) Direct current operable arc lamp
US4035685A (en) Solid cathode cap for an X-ray tube
GB1493065A (en) Electron discharge tubes
US3240978A (en) Cathode assembly for an electron tube
US2451556A (en) Electrode structure for gaseous discharge devices
US2556855A (en) Gaseous discharge device
US2688707A (en) Electron tube structure
US4302701A (en) Directly heated cathode for an electron tube with coaxial electrode design
US3085175A (en) Cathode assembly for electron tube
US2310936A (en) Electron discharge apparatus
US2858470A (en) Cathode for electron discharge devices
US2848641A (en) Vapor electric lamp
US2667593A (en) Electron tube
EP1150334B1 (en) Electrode for discharge tube and discharge tube using it
US2733378A (en) Thermionic cathodes for electronic discharge devices
US1975870A (en) Indirectly heated cathode