US2988666A - Cylindrical dispenser cathode for magnetrons - Google Patents

Cylindrical dispenser cathode for magnetrons Download PDF

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Publication number
US2988666A
US2988666A US468922A US46892254A US2988666A US 2988666 A US2988666 A US 2988666A US 468922 A US468922 A US 468922A US 46892254 A US46892254 A US 46892254A US 2988666 A US2988666 A US 2988666A
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US
United States
Prior art keywords
cathode
magnetrons
tube
rings
cylindrical
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
US468922A
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English (en)
Inventor
Goor Johannes Antonius Van De
Hinkel Karl Walter
Lemmens Hendrikus Johannes
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
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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
Application filed by US Philips Corp filed Critical US Philips Corp
Application granted granted Critical
Publication of US2988666A publication Critical patent/US2988666A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • 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
    • 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

  • This invention relates to cylindrical cathodes, of which the electron-emitting part comprises a porous tungsten body which closes a chamber containing a supply of alkaline-earth metal compounds which during the operation of the cathode supplies alkaline-earth metal to the porous surface of the cathode.
  • the invention also relates to magnetrons comprising such cathodes.
  • annular tungsten body tightly surrounds a molybdenum tube which under the tungsten body has a smaller outer diameter such that a supply chamber is formed between this pant and the porous tungsten body.
  • the porous tungsten body is enclosed in the axial direction between two heavy molybdenum rings pressed on the tube.
  • a difficulty in the known cathode type is that leaks are liable to occur between the rings and the tungsten body due to the diflerent coeflicients of expansion of tungsten and molybdenum. Due to these leaks, an amount of alkaline-earth metal emerges such that part of the rings may also start to emit electrons, either primary or secondary electrons. This emission causes a materially decreased efliciency more particularly in magnetrons.
  • the object of the invention is to provide a cathode construction in which the above-mentioned disadvantages are avoided.
  • a cylindrical annular supply chamber is formed between two porous cylindrical tungsten rings of different diameters, of which at least one comprises flanges directed towards the other, which flanges are intimately connected by welding seams to the terminal surfaces of the flanges of the other ring.
  • the said porous tungsten body is slipped on a molybdenum tube so as to tightly fit thereon and is enclosed between the molybdenum rings having outer diameters equal to that of the porous tungsten body.
  • One of the said rings may be manufactured in one piece with the tube.
  • the construction according to the invention affords the advantage that the welding seam is located inside the cathode body instead of at its surface, so that unnecessary unevennesses thereon are avoided.
  • the inner wall of the supply chamber in itself need not be porous, but solid tungsten is diflicult to work. Diffusion of barium in the direction of the heating filament of the cathode is avoided by the molybdenum tube carrying the tungsten body.
  • reference numeral 1 indicates a molybdenum tube, one extremity of which merges into a thicker portion 2.
  • a molybdenum tube 3 having an outer diameter equal to that of the thicker portion 2 is slipped on the molybdenum tube 1.
  • Pinched between the thicker portion 2 and the tube 3 is a tungsten body 4 comprising a cylindrical outer ring 5 and a cylindrical inner ring 6 comprising two small flanges 7.
  • the flanges 7 and the ring 5 are intimately connected together by means of two annular welding scams 8.
  • the room between the rings 5 and 6 contains a certain amount of barium-strontium carbonate 9 which is disintegrated into oxides after the cathode has been incorporated in the tube.
  • the heating filament of the cathode (not shown) is arranged inside the tube 1.
  • the heating filament of the cathode (not shown) is arranged inside the tube 1.
  • the rings 10 for focusing the electron current in the magnetron.
  • the porous tungsten body 5 When used in a magnetron, the porous tungsten body 5 only is electron-emitting and any appreciable so-called final emission does not occur.
  • a cathode assembly comprising a molybdenum tube having spaced apart ring-like portions, a pair of porous tungsten rings of different diameters securely positioned between said ring-like portions of the molybdenum tube and defining a cavity containing a supply of alkaline earth compounds capable of furnishing alkaline earth metal to an emissive surface, the diameter of the larger ring being equal to the outer diameter of the ring-like portions of the molybdenum tube, one of said tungsten rings being provided with flanges having terminal surface portions secured to abutting surface portions of the other ring by internal welded seams.

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  • Microwave Tubes (AREA)
US468922A 1953-12-22 1954-11-15 Cylindrical dispenser cathode for magnetrons Expired - Lifetime US2988666A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
NL326751X 1953-12-22

Publications (1)

Publication Number Publication Date
US2988666A true US2988666A (en) 1961-06-13

Family

ID=19784195

Family Applications (1)

Application Number Title Priority Date Filing Date
US468922A Expired - Lifetime US2988666A (en) 1953-12-22 1954-11-15 Cylindrical dispenser cathode for magnetrons

Country Status (7)

Country Link
US (1) US2988666A (nl)
BE (1) BE534280A (nl)
CH (1) CH326751A (nl)
DE (1) DE1034780B (nl)
FR (1) FR1116098A (nl)
GB (1) GB757066A (nl)
NL (2) NL183830B (nl)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3286119A (en) * 1963-05-08 1966-11-15 Hitachi Ltd Hollow cathode discharge tubes

Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2543728A (en) * 1947-11-26 1951-02-27 Hartford Nat Bank & Trust Co Incandescible cathode
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
GB713140A (en) * 1951-07-20 1954-08-04 Philips Electrical Ind Ltd Improvements in or relating to the manufacture of dispenser cathodes
US2698913A (en) * 1951-11-29 1955-01-04 Philips Corp Cathode structure
US2700118A (en) * 1951-11-29 1955-01-18 Philips Corp Incandescible cathode
GB731454A (en) * 1952-10-28 1955-06-08 Vickers Electrical Co Ltd Improvements relating to electron emissive devices
US2716716A (en) * 1951-11-29 1955-08-30 Philips Corp Cathode containing a supply of an electron-emissive material
US2733378A (en) * 1956-01-31 Thermionic cathodes for electronic discharge devices
US2750527A (en) * 1951-11-19 1956-06-12 Siemens Ag Cathode for electrical discharge device

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CH236119A (de) * 1942-03-18 1945-01-15 Fides Gmbh Indirekt geheizte Glühkathode.
DE899235C (de) * 1951-06-09 1953-12-10 Siemens Ag Kathode fuer elektrische Entladungsgefaesse
DE885757C (de) * 1951-07-12 1953-08-06 Siemens Ag Kathode fuer elektrische Entladungsgefaesse
AT176925B (de) * 1951-07-20 1953-12-10 Philips Nv Verfahren zur Herstellung einer Vorratskathode
AT176926B (de) * 1951-11-29 1953-12-10 Philips Nv Zylindrische Vorratskathode, insbesondere für eine Magnetronröhre

Patent Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2733378A (en) * 1956-01-31 Thermionic cathodes for electronic discharge devices
US2543728A (en) * 1947-11-26 1951-02-27 Hartford Nat Bank & Trust Co Incandescible cathode
US2673277A (en) * 1949-10-25 1954-03-23 Hartford Nat Bank & Trust Co Incandescible cathode and method of making the same
GB713140A (en) * 1951-07-20 1954-08-04 Philips Electrical Ind Ltd Improvements in or relating to the manufacture of dispenser cathodes
US2750527A (en) * 1951-11-19 1956-06-12 Siemens Ag Cathode for electrical discharge device
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
US2677778A (en) * 1952-03-31 1954-05-04 Atomic Energy Commission Linear cathode
GB731454A (en) * 1952-10-28 1955-06-08 Vickers Electrical Co Ltd Improvements relating to electron emissive devices

Also Published As

Publication number Publication date
DE1034780B (de) 1958-07-24
NL85507C (nl)
CH326751A (de) 1957-12-31
BE534280A (nl)
FR1116098A (fr) 1956-05-03
GB757066A (en) 1956-09-12
NL183830B (nl)

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