US3716750A - Magnetrons - Google Patents

Magnetrons Download PDF

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Publication number
US3716750A
US3716750A US00142641A US3716750DA US3716750A US 3716750 A US3716750 A US 3716750A US 00142641 A US00142641 A US 00142641A US 3716750D A US3716750D A US 3716750DA US 3716750 A US3716750 A US 3716750A
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United States
Prior art keywords
magnetron
magnetron tube
permanent magnets
tube
side surfaces
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Expired - Lifetime
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US00142641A
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English (en)
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K Nakada
T Oguro
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F28—HEAT EXCHANGE IN GENERAL
    • F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
    • F28F1/00—Tubular elements; Assemblies of tubular elements
    • F28F1/10—Tubular elements and assemblies thereof with means for increasing heat-transfer area, e.g. with fins, with projections, with recesses
    • F28F1/105—Tubular elements and assemblies thereof with means for increasing heat-transfer area, e.g. with fins, with projections, with recesses the means being corrugated elements extending around the tubular elements
    • 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
    • H01J23/005—Cooling methods or arrangements
    • 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
    • H01J23/10—Magnet systems for directing or deflecting the discharge along a desired path, e.g. a spiral path

Definitions

  • ABSTRACT In a magnetron device of the class comprising a mag- May 30, 1970 Japan ..45/46034 netron tube permanent magnets on radially pp sides of the magnetron tube yoke means for applying a [52] U.S. Cl.
  • the prior art magnetron device of this type generally comprises an evacuated magnetron tube, a pair of permanent magnets disposed on radially opposite sides and the axis of the permanent magnets being coincident with a plane passing through the longitudinal axis of the magnetron tube and yokes interconnecting the magnets for applying an intense magnetic field to the magnetron tube.
  • the magnetron tube generates a large quantity of heat during its operation.
  • a large quantity of heat not only lowers the vacuum in the magnetron tube but also adversely affects the magnetic characteristics of the permanent magnets disposed in the neighborhood of the tube.
  • the permanent magnets comprise sintered ferrite magnets, the deterioration of their magnetic characteristic is so excessive as to affect the operating characteristics of the magnetron. For this reason, it is the practice to surround the magnetron tube with heat dissipating means for efficiently dissipating the heat generated during the operation thereof.
  • Another object of this invention is to provide an improved magnetron device wherein a magnetron tube is disposed in a magnetic circuit comprising permanent magnets and yokes without increasing the leakage flux.
  • Still another object of this invention is to provide a novel magnetron device utilizing a small permanent magnet which is capable of generating a field of the required intensity for the magnetron tube.
  • a further object of this invention is to provide an improved magnetron of small size and light weight, including means for efficiently dissipating heat therein.
  • a mag netron device of the class comprising a magnetron tube, permanent magnet means disposed in parallel to the magnetron tube for applying a magnetic flux across the magnetron tube and cooling means surrounding the magnetron tube, and at least a portion of the permanent magnet means being characterized in that the widths of the permanent magnets are gradually decreased toward the magnetron tube, thus forming tapered side surfaces.
  • FIG. 1 shows a front elevation of one embodiment of the magnetron in accordance with the invention
  • FIG. 2 shows a cross-sectional view of the magnetron shown in FIG. 1, taken along Line IIII;
  • FIG. 3 shows a diagram illustrating the relationship between the magnetron tube and the permanent magnet constructed according to the teachings of the invention
  • FIGS. 4 and S are diagrammatic representations showing the relationship between the cross-sectional configurations of the magnetron tube and the permanent magnet.
  • FIG. 6 shows a cross-sectional view of a modified embodiment of the invention.
  • FIGS. 1 and 2 illustrate a preferred embodiment of this invention in the form of a magnetron device utilizing radial fins as the heat dissipating means for the magnetron tube.
  • the magnetron shown therein comprises an evacuated magnetron tube or envelope 1, an insulator bushing 2 of ceramic or glass, for example, for housing an output terminal lead 3, permanent magnets 4 and 5 with their pole faces S and N interconnected with the magnetron tube 1 by magnetic yokes 6 and 7, heat dissipating or cooling fins 8 radially extending about the longitudinal axis of the magnetron tube 1 and a duct 9 for passing cooling air along the surface of the cooling fins.
  • FIG. 1 The front elevation shown in FIG. 1 is not different from that of the conventional magnetron; however, the cross-sectional view of FIG. 2 clearly shows the novel relationship between the magnetron tube and the permanent magnets as well as the novel cross-sectional shape of the permanent magnets.
  • the magnetron tube 1 comprises a cathode electrode 11 and an anode electrode 12 concentric with the cathode electrode, and including a plurality of vanes 13 radially protruding toward the cathode electrode for defining a plurality of resonant cavities. Between the cathode electrode and the anode vanes is defined a cylindrical interaction space 14 in which the magnetic field created by the flux generated by the two permanent magnets 4 and flowing through the 5 and yokes 6 and 7 coacts with the electron current flowing from cathode electrode 11 to anode vanes 13.
  • This construction of the magnetron tube 1 has been well known in the art.
  • the permanent magnets 4 and 5 are disposed on the radially opposite sides of and in parallel with the magnetron tube 1 and are positioned as close as possible to the magnetron tube.
  • the invention is characterized in that the width of the inner side walls 41 and 51 of the permanent magnets confronting the peripheral wall of the magnetron tube is a minimum and the width of the magnets gradually increases from these inner side walls toward the outside, and that the direction of the tapered surfaces 42 and 52 substantially coincides with that of the radial cooling fins 8.
  • FIG. 3 The relationship between the magnetron tube and the permanent magnets can be more fully appreciated from FIG. 3. Assuming a permanent magnet whose cross-section can be shown by a rectangle 43, the inside corners of the magnet are cut away along straight lines 1 and 1 that extend radially outwardly from the center 0 of the magnetron tube 1, thus forming a permanent magnet 4 of a configuration shown in FIG. 2. The quantity of flux generated by permanent magnet 4 having such tapered cuts is conducive to the efficient operation of the magnetron. Such a permanent magnet with tapered cuts is equivalent to a rectangular permanent magnet 44 having the same axial length and the same contains sectional area as depicted by the dot and dash lines in FIG. 3.
  • the magnet 4 and the equivalent magnet 44 were made of the same material, they would produce the same quantity of magnetic flux, thus applying to the magnetron tube magnetic fields of the same intensity.
  • the heat dissipating means in regions to the left of radial lines I, and 1 whereas, in the case of the equivalent magnet 44 of rectangular section, regions in which the heat dissipating means can be disposed are limited by the corners 45 of the magnet, or to the left of radial lines 1 and 1 passing through corners 45.
  • the ratio of angle A subtended by line 1 and the normal line through the center 0 of the magnetron and angle B subtended by line and the normal line through the center is equal to 1.4, which indicates a corresponding increase in the heat dissipation.
  • FIG. 4 shows a modified embodiment of the invention wherein permanent magnet 4 is formed by cutting off portions of a cylindrical block along radial lines I and 1,, thus providing tapered side surfaces.
  • the permanent magnet 4 is formed by cutting an annulus of magnetic material along radial lines 1 and 1
  • the body of the permanent magnet may have any desired sectional configuration before it is cutinto a permanent magnet 4 along radial lines passing through the center 0 of the magnetron tube; for example, it may have the shape of an oval.
  • the permanent magnets are disposed as close as possible to the magnetron tube for the purpose of decreasing the leakage of the flux passing through the space between the yokes on the way from the permanent magnets to the magnetron tube, it is possible to decrease the size of the permanent magnets by an amount corresponding to the decrease in the leakage flux.
  • tapered inner ends of the pole pieces of the magnets eliminate the limitation of the regions in which the heat dissipating means can be arranged imposed by the close disposition of the magnets to the magnetron tube, whereby the high heat dissipation efficiency of the prior design can be preserved.
  • the invention has been applied to magnetrons of the type wherein the heat dissipating means comprise radial fins and wherein the cooling air flows in the axial direction of the magnetron tube, it should be understood that the invention is by no means limited to the particular type.
  • a plurality of axially spaced apart parallel flat cooling fins 10 may be provided perpendicular to the longitudinal axis of the magnetron tube for transferring heat to the cooling air flowing in transverse direction to the magnetron tube axis passing between the fins.
  • a magnetron device comprising an evacuated magnetron tube of generally cylindrical configuration, a pair of permanent magnets disposed in close relationship to and extending along the sides of said magnetron tube radially opposite to each other, the widths of said permanent magnets confronting the magnetron tube gradually decreasing toward the axis of said magnetron tube, thus forming tapered side surfaces on said permanent magnets, magnetic yoke means interconnecting the common ends of said permanent magnets for applying a magnetic field to said magnetron tube, and cooling means surrounding said magnetron tube and at least a portion of said tapered side surfaces of said permanent magnets for conveying heat therefrom.
  • cooling means comprises a plurality of cooling fins radially extending from said magnetron tube, said tapered side surfaces coextending with said cooling fins.
  • cooling means comprises a plurality of spaced apart parallel flat fins disposed at substantially perpendicular to the axis of said magnetron tube.
  • cooling means comprises a plurality of cooling fins radially extending from said magnetron tube, said tapered side surfaces coextending with said cooling fins.
  • cooling means comprises a plurality of spaced apart parallel flat fins disposed at substantially perpendicular to the axis of said magnetron tube.
  • a magnetron device comprising an evacuated magnetron tube having a generally cylindrical configuration, a pair of permanent ferrite magnets disposed in close relationship to and extending along the sides of said magnetron tube on radially opposite sides thereof, the widths of said permanent magnets confronting the magnetron tube gradually decreasing toward said magnetron tube, thus forming tapered side surfaces on said permanent magnets, magnetic yoke means interconnecting said permanent magnets for applying a magnetic field to said magnetron tube, and cooling means surrounding said magnetron tube and at least a portion of said tapered side surfaces of said permanent magnets for conveying heat therefrom, said means comprising a plurality of cooling fins extending radially from said magnetron tube and said tapered side surfaces of said magnets coextending with said cooling fins.
  • a magnetron device comprising an evacuated magnetron tube having a generally cylindrical configuration, a pair of permanent ferrite magnets disposed in close relationship to and in parallel with said magnetron tube on radially opposite sides thereof, the widths of said permanent magnets confronting the magnetron tube gradually decreasing toward said magnetron tube, thus forming tapered side surfaces on said permanent magnets which extend in the radial direction with respect to the axis of said magnetron tube, magnetic yoke means interconnecting said permanent magnets for applying a magnetic field to said magnetron tube, and cooling means surrounding said magnetron tube and at least a portion of said tapered side surfaces of said permanent magnets for conveying heat therefrom, said means comprising a plurality of cooling fins extending radially from said magnetron tube and said tapered side surfaces of said magnets coextending with said cooling fins.

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Geometry (AREA)
  • Thermal Sciences (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Microwave Tubes (AREA)
US00142641A 1970-05-13 1971-05-12 Magnetrons Expired - Lifetime US3716750A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP1970046034U JPS5116219Y1 (de) 1970-05-13 1970-05-13

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US3716750A true US3716750A (en) 1973-02-13

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US00142641A Expired - Lifetime US3716750A (en) 1970-05-13 1971-05-12 Magnetrons

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US (1) US3716750A (de)
JP (1) JPS5116219Y1 (de)
DE (1) DE2123577C3 (de)
FR (1) FR2095005A5 (de)
GB (1) GB1316031A (de)
SE (1) SE363927B (de)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3794879A (en) * 1972-10-24 1974-02-26 Raytheon Co Microwave magnetron
US4296355A (en) * 1978-11-13 1981-10-20 Toshiba Corporation Magnetron with cooling means
FR2691856A1 (fr) * 1992-05-28 1993-12-03 Litton Systems Inc Ailette d'anode d'amplificateur à champs croisés à ondes avant refroidie de façon interne.
EP0898139A2 (de) * 1997-08-19 1999-02-24 Grüter Elektroapparate Ag Wärmetauscher, insbesondere für eine Heiz- und Kühlanordnung eines Extruderrohres
US20040026067A1 (en) * 2000-09-01 2004-02-12 Hitoshi Mochizuki Heat exchanger for stirling refrigerating machine, heat exchanger body, and method of manufacturing heat exchanger body
US20120235564A1 (en) * 2011-03-17 2012-09-20 E2V Technologies (Uk) Limited Magnetron
US20150083713A1 (en) * 2012-03-01 2015-03-26 Inova Lab S.R.L. Device for induction heating of a billet

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2765425A (en) * 1946-03-01 1956-10-02 Millman Sidney Magnetron
US3454824A (en) * 1968-02-27 1969-07-08 Fujitsu Ltd Non-uniform magnetic field magnetron device
US3493810A (en) * 1968-02-16 1970-02-03 Litton Precision Prod Inc Magnetron construction
US3562579A (en) * 1968-06-11 1971-02-09 Nippon Electric Co Electron discharge device employing inexpensive permanent magnets if significantly reduced size
US3588588A (en) * 1968-06-21 1971-06-28 Matsushita Electronics Corp Magnetron device with exiting permanent magnet free from magnetic short-circuiting by frame

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2765425A (en) * 1946-03-01 1956-10-02 Millman Sidney Magnetron
US3493810A (en) * 1968-02-16 1970-02-03 Litton Precision Prod Inc Magnetron construction
US3454824A (en) * 1968-02-27 1969-07-08 Fujitsu Ltd Non-uniform magnetic field magnetron device
US3562579A (en) * 1968-06-11 1971-02-09 Nippon Electric Co Electron discharge device employing inexpensive permanent magnets if significantly reduced size
US3588588A (en) * 1968-06-21 1971-06-28 Matsushita Electronics Corp Magnetron device with exiting permanent magnet free from magnetic short-circuiting by frame

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3794879A (en) * 1972-10-24 1974-02-26 Raytheon Co Microwave magnetron
US4296355A (en) * 1978-11-13 1981-10-20 Toshiba Corporation Magnetron with cooling means
FR2691856A1 (fr) * 1992-05-28 1993-12-03 Litton Systems Inc Ailette d'anode d'amplificateur à champs croisés à ondes avant refroidie de façon interne.
EP0898139A2 (de) * 1997-08-19 1999-02-24 Grüter Elektroapparate Ag Wärmetauscher, insbesondere für eine Heiz- und Kühlanordnung eines Extruderrohres
EP0898139A3 (de) * 1997-08-19 2000-05-24 Grüter Elektroapparate Ag Wärmetauscher, insbesondere für eine Heiz- und Kühlanordnung eines Extruderrohres
US6095236A (en) * 1997-08-19 2000-08-01 Grueter Elektroapparate Ag Heat exchanger, in particular for a heating and cooling configuration of an extruder barrel
US20040026067A1 (en) * 2000-09-01 2004-02-12 Hitoshi Mochizuki Heat exchanger for stirling refrigerating machine, heat exchanger body, and method of manufacturing heat exchanger body
US7225859B2 (en) * 2000-09-01 2007-06-05 Sharp Kabushiki Kaisha Heat exchanger element and heat exchanger member for a stirling cycle refrigerator and method of manufacturing such a heat exchanger member
US20120235564A1 (en) * 2011-03-17 2012-09-20 E2V Technologies (Uk) Limited Magnetron
US9318296B2 (en) * 2011-03-17 2016-04-19 E2V Technologies (Uk) Limited Magnetron
US20150083713A1 (en) * 2012-03-01 2015-03-26 Inova Lab S.R.L. Device for induction heating of a billet
US10462855B2 (en) * 2012-03-01 2019-10-29 Inova Lab S.R.L. Device for induction heating of a billet

Also Published As

Publication number Publication date
GB1316031A (en) 1973-05-09
DE2123577A1 (de) 1972-02-17
DE2123577C3 (de) 1975-07-24
SE363927B (de) 1974-02-04
FR2095005A5 (de) 1972-02-04
DE2123577B2 (de) 1974-12-12
JPS5116219Y1 (de) 1976-04-28

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