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US2592206A - Magnetron - Google Patents

Magnetron Download PDF

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Publication number
US2592206A
US2592206A US654934A US65493446A US2592206A US 2592206 A US2592206 A US 2592206A US 654934 A US654934 A US 654934A US 65493446 A US65493446 A US 65493446A US 2592206 A US2592206 A US 2592206A
Authority
US
United States
Prior art keywords
cathode
electrons
space
coated
discharge device
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
US654934A
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English (en)
Inventor
Robert L Sproull
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.)
RCA Corp
Original Assignee
RCA 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 BE471896D priority Critical patent/BE471896A/xx
Priority to NL67823D priority patent/NL67823C/xx
Application filed by RCA Corp filed Critical RCA Corp
Priority to US654934A priority patent/US2592206A/en
Priority to FR943339D priority patent/FR943339A/fr
Priority to GB7363/47A priority patent/GB640255A/en
Application granted granted Critical
Publication of US2592206A publication Critical patent/US2592206A/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
    • H01J25/00—Transit-time tubes, e.g. klystrons, travelling-wave tubes, magnetrons
    • H01J25/50—Magnetrons, i.e. tubes with a magnet system producing an H-field crossing the E-field
    • H01J25/52—Magnetrons, i.e. tubes with a magnet system producing an H-field crossing the E-field with an electron space having a shape that does not prevent any electron from moving completely around the cathode or guide electrode
    • H01J25/58—Magnetrons, i.e. tubes with a magnet system producing an H-field crossing the E-field with an electron space having a shape that does not prevent any electron from moving completely around the cathode or guide electrode having a number of resonators; having a composite resonator, e.g. a helix
    • H01J25/587—Multi-cavity magnetrons
    • 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

Definitions

  • My invention relates to electron discharge devices useful at very high frequencies and more particularly to magnetrons.
  • a further object of my invention is to provide a magnetron useful as an oscillator and having a longer life than those magnetrons now available.
  • a still further object of my invention is to provide an electron discharge device of the magnetron type in which the large noise modulation of the output power is substantially eliminated.
  • t is an object of my invention to neutrali'ze the effect of returned electrons in a magnetron.
  • FIG. 1 is a transverse schematic section of an electron discharge device illustrating the problem solved by my invention
  • Figure 2 is a. transverse section taken along the line 2-2 of Figure 3 and showing details of construction of an electron discharge device made according to my invention
  • Figure 3 is a longitudinal section taken along the line 3-3 of Figure 2
  • Figures 4 and' 5 are transverse sections of'modifications of the cathode construction utilized in the tubes shown in Fgures 2 and 3.
  • I- show a transverse section of a conventional magnetron employing an indirectly heated cathode 9 which may be an elongated tubular member provided with heater, not shown, mounted within an anode block lu provided with a plurality of radially directed slat-like members ll, the inner ends of which provide anode elements or segments 12 defining the anode-cathode space.
  • the slat-like ⁇ members H with the back of the anode block Ill provide cavity resonators between adjacent anode elements
  • the path 'l represents the orbit of an electron leaving the cathode in the wrong phase and causing back bombardment of the cathode.
  • the path 8 represents the orbit of an electron which reaches the anode.
  • My invention provides a cathode which will eliminate the deleterious effects caused by electrons such as those following path 1 in knockng the emitting material from the surface of the cathode and thus causing a shortening of the life of the cathode and ionization in the interaction space which produces the large noise modulation of the output power under some conditions.
  • the anode block Ill is provided With a plurality of inwardly radially directed members Il, the inner ends of which define a space in which the indirectly heated tubular cathode
  • the inner ends of the members H provide the anode elements
  • the anode block IO is closed by the end cover members l'l and
  • the cathode heater leads 19 and 20 are insulatingly sealed at
  • the whole assembly is hermetically sealed to provide a vacuum-tight envelope.
  • the magnetic field is provided by means of the magnet poles 2
  • Energy is coupled out of the resonator in a well-known manner by means of a coaxial line having an outer tubular conductor 23 and inner conductor 24 terminating in the coupling loop 25.
  • the indirectly heated cathode l3 comprises a hollow tubular element of generally-circular cross-section with outwardly-extending longitudinal ribs 21 producing a star-shaped transverse section and in the particular tube shown the cathode was machined of nickel.
  • each of the ribs 21 of the star is coated with electron emitting material on one side face 28 only and left uncoated on the other (face 29.
  • the solid material of the ribs 21 serves as shielding means for the adjacent coated surfaces 28 on the ribs, so that back bombarding electrons cannot strike the coated surfaces 28, and hence, cannot remove the cathode coating material.
  • the result is longer life of the cathode and hence the useful life of the tube is thereby extended and excess noise modulation by gas ionization is prevented.
  • the surfaces of the ribs 21 are inclined at an angle of approximately 60 with respect to a tangent to a cylinder circumscribed about the cathode, and hence, returning electrons which approach the cathode at angles less than 60 cannot bombard the coated faces 28.
  • FIG 4 I show a modification of the cathode shown in Figures 2 and 3.
  • the tubular cathode 30 is again provided with the cathode heater 30' and has secured to its outer surface longitudinally extending radially directed ribs or fins 3
  • Operation is as indicated in Figures 2 and 3. It can be seen that the radial arrangement of Fig. 4 prevents the coated faces 32 from being bombarded by returning electrons approaching the cathode at angles less than 90.
  • FIG. 5 I show a still further modification of my invention.
  • the elongated tubular cathode sleeve 35 has punched out from it ribs or fins 36 coated on one side face 31 and uncoated on the other side face 38.
  • This arrangement protects the coated faces 38 at angles up to approximately 45.
  • the surfaces of the cathode are so formed that the coated surfaces are not exposed to bombardment by returned electrons. rThis is accomplished by providing outwardly-extending longitudinal ribs on the cathode. As a result the life of the tube is increased and excess noise is decreased.
  • An electron discharge device having a plurality of anode elements defining a space, means including a cathode positioned within said space to supply electrons therein and means adjacent said anode elements for generating a magnetic field within said space parallel to the longitudinal axis of said cathode whereby electrons from said cathode are made to travel curved paths during operation of said electron discharge device, said cathode having a plurality of coated emitting surfaces and uncoated surfaces thereon, the space between said cathode and said anode elements being unobstructed, said coated surfaces being disposed out of the paths of electrons leaving the cathode surface and returning to the cathode surface along curved paths.
  • An electron discharge device having a plurality of anode elements defining a space, means including a cathode positioned within said space to supply electrons therein and means adjacent said anode elements for generating a magnetic field within said space parallel to the longitudinal axis of said cathode whereby electrons from said cathode are made to travel curved paths during the operation of said electron discharge device, said cathode having elongated flat surfaces extending longitudinally of said cathode, alternate ones only of said surfaces having emitting coatings, said alternate surfaces being inaccessible to electrons returning to said cathode along curved paths.
  • An electron discharge device having a plurality of anode elements defining a space, means including a cathode positioned within said space to supply electrons therein and means adjacent said anode elements for generating a magnetic field within said space parallel to the longitudinal axis of said cathode whereby electrons from said cathode are made to travel curved paths during the operation of said electron discharge device, said cathode having surfaces lying along planes passing radially through the longitudinal axis of said cathode, alternate surfaces only being coated, said coated surfaces being inaccessible to electrons returned to said cathode along curved paths.
  • An electron discharge device having a plurality of anode elements defining a space, means including a cathode positioned within said space to supply electrons therein and means adjacent said anode elements for generating a magnetic field within said space parallel to the longitudinal axis of said cathode Whereby electrons from said cathode are made to travel curved paths during the operation of said electron discharge device, said cathode including a hollow tubular member having fins extending from the outer surface thereof, said fins being coated with emitting material on one side only, said coated surfaces being inaccessible to electrons returned to said cathode along curved paths.
  • An electron discharge device having a plurality of anode elements defining a space, means including a cathode positioned within said space to supply electrons therein and means adjacent said anode elements for generating a magnetic field within said space parallel to the longitudinal axis of said cathode Whereby electrons from said cathode are made to travel curved paths during the operation of said electron discharge device, said cathode having a star-shaped transverse section whereby longitudinally extending surfaces lie at an angle to each other, and emitting coatings on alternate surfaces only, said alternate surfaces being inaccessible to electrons returned to said cathode along said curved paths.
  • An electron discharge device having a plurality of anode elements defining a space, means including a cathode positioned Within said space to .supply electrons therein, means adjacent said anode elements for generating a magnetic field within said space parallel to the longitudinal axis of said cathode whereby electrons from said cathode are made to travel curved paths during the operation of said electron discharge device, said cathode having flat surfaces extending longitudinally of said cathode, said surfaces lying in planes at angles to each other, alternate surfaces only being coated, said alternate surfaces being inaccessible to electrons returning to said cathode along curved paths.
  • An electron discharge device having a -plurality of anode elements defining a space, means including a cathode positioned within said space to supply electrons therein, and means adjacent said anode elements for generating a magnetic field within said space parallel to the longitudinal axis of said cathode whereby electrons from said cathode are made to travel curved paths during the operation of said electron discharge device, said cathode including a hollow tubular member having punched-out fins extending outwardly from the outer surface thereof, and said fins having coated surfaces on one side only and inaccessible to electrons returned to said cathode along curved paths.
  • An electron discharge device having a plurality of anode elements defining a space, means including a cathode positioned within said space to supply electrons therein, and means adjacent said anode elements for generating a magnetic field Within said space parallel to the longitudinal axis of said cathode Whereby electrons from said cathode are made to travel curved paths during operation of said electron discharge device, said cathode having a plurality of outwardly-projecting longitudinal ribs with emitting coatings on one side surface only, said emitting coatings being inaccessible to electrons returning to said cathode along curved paths.
  • An electron discharge device having a plurality of elongated parallel anode elements defining a cylindrical space, means including an elongated cathode positioned Within said space with its longitudinal axis parallel to said anode elements to supply electrons within said space, and means adjacent said anode elements for generating a magnetic field Within said space vparallel to the longitudinal axis of said cathode whereby electrons from said cathode are made to travel curved paths during operation of said space, means including a lcathode of generally circular cross-section positioned Within said space to supply electrons therein, and means adjacent said anode elements for generating a magnetic field Within said space parallel to the longitudinal axis of said cathode Whereby electrons from said cathode are made to travel curved electron discharge device, said cathode comprising an elongated tubular element having a pluralityv of outwardly-projecting longitudinal ribs uniformly spaced 'around the periphery thereof and having emitting coatings on alternate side
  • An electron discharge device comprising a plurality of anode elements defining a cathode ⁇ paths during operation of said device, said cathode including a plurality of surfaces disposed around the periphery thereof, alternate ones of said surfaces being coated with emitting material and the remaining surfaces being uncoated, said coated-surfaces being disposed out of the paths of electrons leaving said cathode and returning to the cathode along curved paths during operation of said device.
  • An electron discharge device comprising an electron-emissive cathode, an anode adjacent but spaeed from said cathode, and means adjacent said lcathode and anode for generating a magnetic field substantially normal to the paths of electrons from said cathode toward said anode, whereby electrons are caused to return to said cathode along curved paths during operation of said device, said cathode including a plurality of outwardly-projecting ribs, alternate side surfaces only of said ribs being coated with emissive material and being inaccessible to said electrons returning to said cathode.
  • a cathode comprising an elongated tubular element having a plurality of outwardly-projecting longitudinal ribs uniformly disposed around the periphery thereof and having emitting coatings on alternate side surfaces only of said ribs.
  • An elongated cathode comprising an element of generally circular cross section having a plurality of discrete, longitudinallyr-extending, major surfaces of substantially equal area disposed around the periphery thereof, alternate ones only of said major surfaces being coated with emitting material and the intermediate major surfaces being uncoated, each of said coated major surfaces extending generally outwardly from said element.
  • An elongated cathode of generally circular cross section having surfaces lying along planes passing radially through the'longitudinal axis thereof, alternate surfaces only being coated with emitting material.
  • a cathode including a hollow tubular member having longitudinal fins extending from the outer surface thereof, said fins being coated with emitting material on alternate side faces only.
  • An elongated cathode having a star-shaped transverse section With adjacent longitudinallyextending surfaces lying at an angle to each other, and emitting coatings on alternate surfaces only.
  • An elongated cathode comprising an element of generally circular cross section having a plurality of discrete, outwardly-projecting, longitudinally-extending, fiat major faces disposed around the periphery thereof, alternate ones of said major faces being coated with emitting material and the intermediate major faces being uncoated.
  • An electron discharge device comprising a generally cylindrical cathode, a hollow anode coaxially surrounding said cathode, said cathocle comprising a plurality of surfaces coated with electron emissive material, means for generating a magnetic field substantially parallel to the longitudinal axis of said cathode and anode, whereby part of the electrons emitted by said cathode toward said anode are caused to return toward said cathode along curved paths during operation of said device, and uncoated shielding means adjacent to said surfaces and disposed out of the paths of at least half of the electrons leaving said surfaces towai'd said anode but in the paths of said electrons returning toward said cathode along said curved paths and approaching said cathode at angles at least up to approximately 45 thereto, to prevent back bombardment of said coated surfaces by said returning electrons.
  • An electron discharge device according to claim 20, wherein said shielding means is dis- 8 posed in the paths of electrons approaching said cathode at angles up to approximately 90 thereto.
  • An elongated cathode having a plurality of outwardly-projecting longitudinal ribs each having two exterior side faces, alternate side faces only being coated With emitting material.

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  • Microwave Tubes (AREA)
US654934A 1946-03-16 1946-03-16 Magnetron Expired - Lifetime US2592206A (en)

Priority Applications (5)

Application Number Priority Date Filing Date Title
BE471896D BE471896A (fr) 1946-03-16
NL67823D NL67823C (fr) 1946-03-16
US654934A US2592206A (en) 1946-03-16 1946-03-16 Magnetron
FR943339D FR943339A (fr) 1946-03-16 1947-03-15 Perfectionnements aux magnétrons
GB7363/47A GB640255A (en) 1946-03-16 1947-03-17 Improvements in magnetron electron-discharge devices

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US654934A US2592206A (en) 1946-03-16 1946-03-16 Magnetron

Publications (1)

Publication Number Publication Date
US2592206A true US2592206A (en) 1952-04-08

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US654934A Expired - Lifetime US2592206A (en) 1946-03-16 1946-03-16 Magnetron

Country Status (5)

Country Link
US (1) US2592206A (fr)
BE (1) BE471896A (fr)
FR (1) FR943339A (fr)
GB (1) GB640255A (fr)
NL (1) NL67823C (fr)

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2784346A (en) * 1950-01-28 1957-03-05 Rca Corp Electron discharge device
US2802125A (en) * 1951-07-12 1957-08-06 Rca Corp Cathodes
US2992360A (en) * 1953-05-13 1961-07-11 Csf Suppressor device for the secondary emission current in magnetic field electronic tubes
US3315121A (en) * 1961-04-27 1967-04-18 Gen Electric Crossed-field electric discharge device
US3413516A (en) * 1965-08-30 1968-11-26 Gen Electric Crossed-field discharge devices and oscillators and amplifiers incorporating the same
DE1294565B (de) * 1961-04-27 1969-05-08 Gen Electric Magnetronoszillatorroehre
US3458753A (en) * 1965-08-30 1969-07-29 Gen Electric Crossed-field discharge devices and couplers therefor and oscillators and amplifiers incorporating the same
US4380717A (en) * 1978-09-02 1983-04-19 English Electric Valve Company Limited Magnetrons

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2869031A (en) * 1955-03-01 1959-01-13 Brett Herbert Cathode
JPH0760641B2 (ja) * 1985-02-06 1995-06-28 新日本無線株式会社 マグネトロン用陰極
JP4286406B2 (ja) 1999-02-10 2009-07-01 新日本無線株式会社 マグネトロン用陰極

Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2032179A (en) * 1933-04-12 1936-02-25 Westinghouse Electric & Mfg Co Oxide coated cathode for heavy duty service
US2069832A (en) * 1934-12-29 1937-02-09 Bell Telephone Labor Inc Electric discharge device
US2130280A (en) * 1933-04-12 1938-09-13 Telefunken Gmbh Electron discharge tube
US2138918A (en) * 1938-03-24 1938-12-06 Rca Corp Cathode
US2151766A (en) * 1937-08-24 1939-03-28 Telefunken Gmbh Magnetron
US2225259A (en) * 1937-06-28 1940-12-17 Julius Pintsch Kommandit Ges Ultra-high-frequency generator
US2358542A (en) * 1940-07-26 1944-09-19 Rca Corp Currentless grid tube
US2409038A (en) * 1942-12-31 1946-10-08 Rca Corp Magnetron and circuit therefor
US2411601A (en) * 1941-09-30 1946-11-26 Raytheon Mfg Co Electronic discharge device

Patent Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2032179A (en) * 1933-04-12 1936-02-25 Westinghouse Electric & Mfg Co Oxide coated cathode for heavy duty service
US2130280A (en) * 1933-04-12 1938-09-13 Telefunken Gmbh Electron discharge tube
US2069832A (en) * 1934-12-29 1937-02-09 Bell Telephone Labor Inc Electric discharge device
US2225259A (en) * 1937-06-28 1940-12-17 Julius Pintsch Kommandit Ges Ultra-high-frequency generator
US2151766A (en) * 1937-08-24 1939-03-28 Telefunken Gmbh Magnetron
US2138918A (en) * 1938-03-24 1938-12-06 Rca Corp Cathode
US2358542A (en) * 1940-07-26 1944-09-19 Rca Corp Currentless grid tube
US2411601A (en) * 1941-09-30 1946-11-26 Raytheon Mfg Co Electronic discharge device
US2409038A (en) * 1942-12-31 1946-10-08 Rca Corp Magnetron and circuit therefor

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2784346A (en) * 1950-01-28 1957-03-05 Rca Corp Electron discharge device
US2802125A (en) * 1951-07-12 1957-08-06 Rca Corp Cathodes
US2992360A (en) * 1953-05-13 1961-07-11 Csf Suppressor device for the secondary emission current in magnetic field electronic tubes
US3315121A (en) * 1961-04-27 1967-04-18 Gen Electric Crossed-field electric discharge device
DE1294565B (de) * 1961-04-27 1969-05-08 Gen Electric Magnetronoszillatorroehre
US3413516A (en) * 1965-08-30 1968-11-26 Gen Electric Crossed-field discharge devices and oscillators and amplifiers incorporating the same
US3458753A (en) * 1965-08-30 1969-07-29 Gen Electric Crossed-field discharge devices and couplers therefor and oscillators and amplifiers incorporating the same
US4380717A (en) * 1978-09-02 1983-04-19 English Electric Valve Company Limited Magnetrons

Also Published As

Publication number Publication date
NL67823C (fr)
GB640255A (en) 1950-07-19
FR943339A (fr) 1949-03-04
BE471896A (fr)

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