US3870923A - Magnetron with an improved tuning mechanism - Google Patents

Magnetron with an improved tuning mechanism Download PDF

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Publication number
US3870923A
US3870923A US427500A US42750073A US3870923A US 3870923 A US3870923 A US 3870923A US 427500 A US427500 A US 427500A US 42750073 A US42750073 A US 42750073A US 3870923 A US3870923 A US 3870923A
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United States
Prior art keywords
bearer
magnetron
cavities
vacuum
cores
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Expired - Lifetime
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US427500A
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English (en)
Inventor
Yves Peyrard
Jean-Claude Renault
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Thales SA
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Thomson CSF SA
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Publication date
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    • 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
    • H01J23/16—Circuit elements, having distributed capacitance and inductance, structurally associated with the tube and interacting with the discharge
    • H01J23/18—Resonators
    • H01J23/20—Cavity resonators; Adjustment or tuning thereof
    • H01J23/213—Simultaneous tuning of more than one resonator, e.g. resonant cavities of a magnetron

Definitions

  • ABSTRACT A magnetron wherein tuning of the frequency is produced by penetration of conductive cores into its cavities. Said cores are fixed on a bearer and the magnetron comprises means for translating the bearer along its axis and simultaneously maintaining the vacuum in the tube, there'means being designed for biasing said bearer at three points distributed in the neighbourhood of itsperiphery.
  • the present invention relates to magnetrons. It relates more particularly to, the mechanism for tuning the frequency of these electronic tubes.
  • These tubes generally comprise, arranged around an axis and within a cylindrical body, a plurality of electromagnetic cavities, that is to say volumes which are limited on some of their faces by conductive walls, and in which, in operation, a high frequency electromagnetic field is developed.
  • An electron beam issuing from a source located at the centre of the cylindrical body is accelerated towards said cavities, whilst a magnetic field is developed in the direction of the cylinder axis.
  • arrangements are effected in order to make it possible to vary the resonance frequencies of the electromagnetic cavities.
  • the cylindrical body is closed off at its two ends by two faces, perpendicular to the axis of the body, and attached to the latter in a vacuum-tight fashion, a vacuum being maintained within the closed envelope thus constituted.
  • tuning of the frequency is achieved by displacement of electrically conductive cores, or plungers, which are able to penetrate to a greater or lesser extent into the afore mentioned electromagnetic cavities, thus modifying the resonance frequencies of the cavities. It goes without saying that the displacement should be effected without any breaking of the vacuum.
  • the displacement of the plungers was separately realized for each of the cavities, or by the displacement of one of the terminal face of the magnetron, to which were attached the plungers; in this latter embodiment, the method required to produce this displacement was usually applied to the centre of the face and this gave rise to major complications in the installation of the deforming system, due to the presence in this region of the magnet poles.
  • the displacements of all the plungers were not exactly the same and, consequently, the degrees of penetration of the cores into the cavities were not equal too, so that resonance frequencies differed from one cavity to another.
  • the object of the present invention is a tunable magnetron in which these difficulties are avoided.
  • a magnetron comprising:
  • FIG. 1 is a perspective view of a portion of a magnetron illustrating the invention generally.
  • FIG. 2 is a partial cross-sectional view taken along lines II of FIG. 1, and showing additional parts of the magnetron not shown in FIG. 1. It illustrates an embodiment of the invention in detail.
  • FIG. 1 illustrates in perspective one of the faces or covers 1 which close off the cylindrical body of the magnetron comprising the resonant cavities, said body not having been described or illustrated in the present text anymore than have those other elements of the magnetron which are not directly concerned in the invention. Said body, in the figure, would be located beneath the component shown in the figure.
  • it consists of a cylindrical electrically conductive wall equipped around the whole of its circumference with partitions or fins, also electrically conductive, disposed radially and extending towards the interior of the cylinder, up to a certain distance from its centre.
  • partitions delimit the pluralilty of resonant cavities referred to, for example N cavities, which are open at three of their faces: that disposed towards the cylinder axis and those perpendicular to said axis.
  • the cylindrical body in which, in operation, there is a vacuum, is closed off at its other end by a flat base.
  • XX is the axis of the cover 1, and is coincident with that of the magnetron of which it forms part.
  • the cover 1 is constituted by a circular flange 2 with double stepped portions, 3 and 4, at one side, and also stepped, at 5, at the other side.
  • the flange 2 carries an assembly 6 constituted by a bearer 7, disc shapped, of the same diameter as the step or shoulder 5 in the example shown in the figure, to which are attached electrically conductive cores 8, for example N cores.
  • the flange 2 is attached to the assembly 6 in a manner which will be specified hereinafter.
  • Three toothed wheels 17 are also shown on the figure, and are described hereinafter too.
  • the flange 2 of anti-magnetic steel and the cylindrical ring 5, are manufactured separately. Said ring 5 is attached to the flange 2 by brazing, using a silver brazing solder. To a disc 7, machined in anti-magnetic steel, on the other hand a copper ring corresponding to the height of the cores 8, is attached; said ring is brazed to the disc 7 using a silver brazing solder for example. Then, the copper ring is milled in order to produce the cores 8, all having the same dimension in the particular example shown in the FIG. 1.
  • a sub-assembly is produced separately; it is constituted by a deformable diaphragm of generally tubular shape, for example a bellows l terminated by a dished end cover.9 brazed to it at its bottom end and by a flanged ring 11 brazed to the top end of the bellows.
  • the brazed joints of this assembly produced using a known technique, have not been shown simply in order to avoid over-burdening the drawing.
  • This subassembly is installed between the cover 1 and the bearer 7 as the figure shows, the dished ring 9 resting on the assembly 6 and the ring 11 on the flange 2.
  • the dished ring 9, at its centre exhibits a hollow cylindrical body 12, either attached to it or formed integrally with it, which, in the position shown in the drawing, penetrates into a cavity in the core 8 and is flush with the bottom end of the latter.
  • Sub-assembly 9, 10, 11 and 12 is brazed at its two ends on the one hand to the assembly 6 and on the other hand to the flange 2, respectively at 13 and 14.
  • the hollow cylindrical body 12 is provided internally with a blind tapped hole 15, thus constituting a nut, into which there can be screwed a screw 16 terminated in a head 17 having the form of a toothed wheel and forming a gear in other words, the bearer 7 which carries all the cores 8, is driven on three points by the ball bearing 18; the top face of thetoothed wheel 17 is flush with a level located slightly below the lowest point of the step 4.
  • control gear 24 causes the intermediate ring 21 to rotate, and this, in turn, rotates the gears 17 so that the cores 8 move up or down depending upon the direction of rotation. This displacement is made possible, without breaking the vacuum, by the presence of the deformable bellows 10 which provides a vacuum-tight seal vis-a-vis the exterior.
  • the cores 8 thus penetrate to a greater or lesser depth into the cavities contained by the cylindrical body 100. With each position of these cores or plungers 8, there corresponds a resonance frequency on the part of these cavities.
  • reference 32 represents one of the aforementioned fins, separating two successive cavities of the magnetron, and reference 31, in section, represents the coupling element between them.
  • the amplitude of the maximum possible displacement is limited by the distance 33 (shown FIG. 1) between the component 5 and the highest point of the ring 6 (bearer 7). This displacement is at the most some few millimetres for a magnetron operating at a wavelength of 10 cm.
  • the cover 1 carries the three toothed wheels 17, contained in the same plane as FIG. 1 shows.
  • These toothed wheels will preferentially, as in the example of this figure, be arranged at 120 to one another. Thanks to the presence of these three wheels, the bearer 7 and its cores 8, in the course of its displacement, is biased simultaneously by three points distributed uniformly about its axis so that it displaces very substantially along the direction of said axis. Thus, one of the drawbacks of the prior art devices is avoided.
  • the bearer 7 shown in FIG. 1 is integral with a thick metal diaphragm which is rigid and dished to give it a dome shape in the example illustrated, there being a central hole in it which is not visible in the figure.
  • the components 7 and 70 are also made in one piece by stamping a flange. The presence of this diaphragm increases the stiffness of the ring 6 and thus reduces the risk of the latter displacing in a direction out of alignment with the tube axis.
  • a magnetron comprising:
  • tuning cores being attached to a bearer, said bearer being carried by one of said covers;
  • a magnetron as claimed in claim 1, wherein said translational means comprise three screws fixed in the axial direction in relation to said cover and cooperating with three nuts carried by said bearer.
  • sealing means consist of three deformable diaphragms of generally tubular shape, surrounding each of said three screws and attached at one of their ends to said bearer and at the other to said cover.

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  • Microwave Tubes (AREA)
  • Transmission Devices (AREA)
US427500A 1972-12-29 1973-12-26 Magnetron with an improved tuning mechanism Expired - Lifetime US3870923A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
FR7246905A FR2212634B1 (enrdf_load_stackoverflow) 1972-12-29 1972-12-29

Publications (1)

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US3870923A true US3870923A (en) 1975-03-11

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US427500A Expired - Lifetime US3870923A (en) 1972-12-29 1973-12-26 Magnetron with an improved tuning mechanism

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US (1) US3870923A (enrdf_load_stackoverflow)
FR (1) FR2212634B1 (enrdf_load_stackoverflow)
GB (1) GB1425078A (enrdf_load_stackoverflow)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5537002A (en) * 1994-09-12 1996-07-16 Olin Corporation Frequency tunable magnetron including at least one movable backwall
EP2472554A1 (fr) * 2010-12-29 2012-07-04 Thales Dispositif de génération d'ondes hyperfréquence ayant une cathode dont chaque extrémité est raccordée à une source de tension

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2534503A (en) * 1947-06-28 1950-12-19 Rca Corp Frequency-modulated magnetron microwave generator
US2625669A (en) * 1947-02-01 1953-01-13 Raytheon Mfg Co Electron discharge device
US2632131A (en) * 1952-12-10 1953-03-17 Raytheon Mfg Co Tunable magnetron
US2851633A (en) * 1951-06-07 1958-09-09 Csf Multi-cavity resonant circuits
US3414761A (en) * 1965-09-16 1968-12-03 S F D Lab Dither tuner for a coaxial magnetron
US3590313A (en) * 1970-01-22 1971-06-29 Varian Associates Dither tuned microwave tube with corrected tuner resolver output

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
BE480796A (enrdf_load_stackoverflow) * 1944-12-02
US2972085A (en) * 1958-01-15 1961-02-14 Rca Corp Tunable magnetron

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2625669A (en) * 1947-02-01 1953-01-13 Raytheon Mfg Co Electron discharge device
US2534503A (en) * 1947-06-28 1950-12-19 Rca Corp Frequency-modulated magnetron microwave generator
US2851633A (en) * 1951-06-07 1958-09-09 Csf Multi-cavity resonant circuits
US2632131A (en) * 1952-12-10 1953-03-17 Raytheon Mfg Co Tunable magnetron
US3414761A (en) * 1965-09-16 1968-12-03 S F D Lab Dither tuner for a coaxial magnetron
US3590313A (en) * 1970-01-22 1971-06-29 Varian Associates Dither tuned microwave tube with corrected tuner resolver output

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5537002A (en) * 1994-09-12 1996-07-16 Olin Corporation Frequency tunable magnetron including at least one movable backwall
EP2472554A1 (fr) * 2010-12-29 2012-07-04 Thales Dispositif de génération d'ondes hyperfréquence ayant une cathode dont chaque extrémité est raccordée à une source de tension
FR2970114A1 (fr) * 2010-12-29 2012-07-06 Thales Sa Dispositif de generation d'ondes hyperfrequence ayant une cathode dont chaque extremite est raccordee a une source de tension

Also Published As

Publication number Publication date
FR2212634A1 (enrdf_load_stackoverflow) 1974-07-26
GB1425078A (en) 1976-02-18
FR2212634B1 (enrdf_load_stackoverflow) 1976-10-29

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