EP0593768B1 - Magnetron - Google Patents

Magnetron Download PDF

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Publication number
EP0593768B1
EP0593768B1 EP92915517A EP92915517A EP0593768B1 EP 0593768 B1 EP0593768 B1 EP 0593768B1 EP 92915517 A EP92915517 A EP 92915517A EP 92915517 A EP92915517 A EP 92915517A EP 0593768 B1 EP0593768 B1 EP 0593768B1
Authority
EP
European Patent Office
Prior art keywords
magnetron
emission
primary
emission element
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
EP92915517A
Other languages
German (de)
English (en)
French (fr)
Other versions
EP0593768A4 (en
EP0593768A1 (en
Inventor
Mikhail Fedorovich Kopylov
Boris Vasilievich Bondarenko
Vladimir Iliich Makhov
Viktor Alexandrovich Nazarov
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.)
PROIZVODSTVENNOE OBIEDINENIE "PLUTON"
Original Assignee
PROIZVODSTVENNOE OBIEDINENIE "PLUTON"
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Publication date
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Publication of EP0593768A1 publication Critical patent/EP0593768A1/en
Publication of EP0593768A4 publication Critical patent/EP0593768A4/en
Application granted granted Critical
Publication of EP0593768B1 publication Critical patent/EP0593768B1/en
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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
    • H01J23/06—Electron or ion guns
    • H01J23/075—Magnetron injection guns
    • 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

Definitions

  • the present invention relates to microwave electronic devices, particularly, to a magnetron.
  • a magnetron (US,A, 3109123), comprising an anode, and, a cathode which has a portion of its surface made in the form of disks with sharp edges with a plurality of thin wires arranged thereon to concentrate the electric field.
  • the magnetron is provided with screens of a special shape which are fed by different potentials relative to the cathode core.
  • the magnetron cannot however be excited solely by the presence of sharp edges and a plurality of wires as these features fail to provide the necessary autoelectronic emission and an electric discharge process is therefore necessary.
  • a magnetron comprising an anode and a cathode, with the cathode arranged coaxially inside the anode and made in the form of a rod whose surface is provided with alternating elements enabling primary and secondary emissions.
  • the elements ensuring the primary and secondary emissions in the magnetron are provided on the cathode surface in the form of alternating stripes of emission-active substances providing, respectively, for the primary and secondary emission.
  • the value of the electric field intensity is not indicated on the elements ensuring the primary emission, which is necessary for field excitation of the magnetron.
  • the electric field intensity of 5,10 5 V/cm is not sufficient for the cold emission and, therefore, a coating in the form of stripes or rings, parallel or perpendicular to the cathode axis and intended for the emission of electrons, cannot ensure the field emission necessary for initiating the magnetron.
  • the presence of two different coatings ensuring the emission of electrons in a cold state and the secondary electron emission cannot be stable during the time of the magnetron operation as the active substance is transferred from the cathode to the anode and vice verse and, as a result, a homogeneous mixed coating is formed all over the surface of the cathode. So, the field (cold) excitation of the magnetron is not ensured.
  • the cathode surface coated with emission-active substances rapidly deteriorates as a result of its bombardment by negative ions.
  • the given magnetron does not ensure an instantaneous firing (with the first pulse) without preliminary heating-up of the cathode and without transmission of an input (exciting) signal, and cannot be reliable and durable.
  • the present invention resides in providing a magnetron whose design and production technology, as well as respective selection of compatible materials of the elements ensuring the primary and secondary emission would allow instantaneous firing (with the first pulse) without preliminary heating-up of the cathode, increasing the service life and improving reliability of the magnetron proper and of the switching device in which the magnetron operates, owing to the provision of the electric field intensity, necessary for obtaining the field emission sufficient in value for exciting the magnetron.
  • a magnetron comprising an anode and a cathode installed coaxially in the anode and made in the form of a cylindrical rod provided with alternating primary-emission and secondary-emission elements arranged on it, wherein the secondary emission element is made in the form of at least one cylindrical bush of an emission active material, characterized in that the primary-emission element is made in the form of at least one flat disk of a refractory metal having a thickness ranging from fractions of micron to several micron and provided with a central hole, the primary emission and secondary emission elements being installed coaxially so that the external diameter of the flat disk exceeds the external diameter of the cylindrical bush by a value ranging from 0.1 to 0.2 of the interelectrode gap value and the end faces of the adjacent flat disk and cylindrical bush adjoin each other.
  • Such an arrangement of the flat disk with respect to the cylindrical bush ensures sufficiently high concentration of the electric field on the disk edge owing to coefficient ⁇ of the shape-factor and thus reliable excitation of the magnetron.
  • the central hole provided in the flat disk and coaxial installation of the disk and cylindrical bush provides for a uniform projection of the primary-emission element over the surface of the secondary-emission element all around the circumference. If the external diameters of the primary-emission elements are made larger than those of the secondary-emission elements by a value greater than 0.2 of the interelectrode gap value, the primary-emission element finds itself outside the space charge cloud and deteriorates. Besides, an unstable operation of the magnetron in the form of sparking takes place. If the projecting portion of the primary-emission element is less than 0.1 of the value of the interelectrode gap, the preset value of the electric field intensity required for obtaining the field emission cannot be ensured.
  • the embodiment of the primary-emission and secondary emission elements in the predetermined form and from the predetermined materials, and the provision of the electric field intensity necessary for obtaining the field emission sufficient in value ensure the magnetron excitation and its instantaneous firing (with the first pulse) without preliminary heating-up of the cathode also the magnetron service life is increased and reliability is improved, as well as reliable operation being provided for of the transmitting device in which the magnetron is utilized.
  • the primary-emission element should be made in the form of five flat disks and the secondary-emission element, in the form of four cylindrical bushes manufactured from an emission-active material.
  • each cylindrical bush be in the form of a truncated cone whose smaller base adjoins the end face of the respective flat disk and the greater base diameter serves as the external diameter of the cylindrical bush.
  • annular groove is formed with the end faces made in the form of a truncated cone.
  • the annular groove decreases the screening effect of the secondary-emission element, thus increasing the electric field intensity.
  • the end faces of the adjacent flat disk and cylindrical bush should adjoin each other through a flat cylindrical protective washer made of a thin refractory metal foil, the thickness of the flat cylindrical protective washer being at least five to ten times greater than that of the flat disk.
  • the presence of protective washers makes it possible to eliminate deterioration of the primary-emission elements caused by mechanical and chemical effect on them of the secondary-emission elements.
  • the protective washer manufactured from a superfine foil of a recractory metal whose thickness is at least five to ten times greater than the thickness of the flat disk, ensures reliable protection of the disk against deterioration due to physicochemical processes taking place at the point of contact of the flat disk and the cylindrical bush.
  • the primary-emission element should be manufactured from one of refractory metals, such as Ta, Nb and W.
  • refractory metals Ta, Nb, W for manufacfuring the primary-emission element makes it possible to stabilize the field emission.
  • the primary-emission element should be manufactured from tungsten-and-tantalum alloy.
  • alloys of refractory metals for the primary-emission elements makes it possible to stabilize the field emission and ensure their stable shapes.
  • the present invention makes it possible to attain an instantaneous initiating ; (with the first pulse) of the magnetron without preliminary heating-up of the cathode, to increase the service life of the magnetron and improve its reliability, as well as reliability of the transmitting device in which the magnetron operates owing to the provision of the electric field intensity necessary for obtaining the field emission sufficient in its value for the magnetron excitation.
  • the present invention enables filamentless magnetrons to be constructed with the field excitation in two- and three-centimeter and millimeter bands for high-frequency pulses of different power.
  • magnetrons are characterized by their instantaneous settling (first pulse readiness), high reliability and durability exceeding ten thousand hours, a possibility of fast change from the small pulse ratio mode to the great pulse ratio mode and vice verse, and a high economical efficiency due to the absence of the power consumption in the filament circuit.
  • the use of such magnetrons in transmitting devices makes it possible to essentially simplify their circuits and decrease their overall dimensions and weight, since approximately fifty radio components are excluded from their circuits.
  • FIG. 1 of the accompanying drawings A preferred embodiment of a magnetron constructed according to the present invention is illustrated in Fig. 1 of the accompanying drawings and comprises an anode 1 ( Figure 1) and a cathode installed coaxially inside the anode and made in the form of a cylindrical hollow rod 2 with primary-emission and secondary-emission elements, arranged on its surface, their end faces adjoining each other.
  • a primary-emission element is made in the form of at least one flat disk 3 provided with a central hole and made of a superfine foil of a refractory metal.
  • the primary-emission element is made in the form of one flat disk 3 having the thickness ranging from fractions of a micron to several microns and manufactured by stamping or an electroerosion method.
  • a secondary-emission element is made in the form of at least one cylindrical bush 4 manufactured from an emission-active material and installed coaxially with the disk 3 and rod 2.
  • the secondary-emission element is made in the form of one cylindrical bush 4.
  • the secondary-emission elements may be impregnated cathodes or cathodes based on metals alloys including plauinum group metals, such as Pt, Ir, Os, Ru, Rh, Pd with admixtures of acitvators in the form of one or several elements of alkali-earth metals (Ba, Sr, Ca).
  • Two focusing screens 5 are arranged on, and coaxially with the hollow cylindrical rod 2, which may be made of molybdenum or other refractory metal or their alloys.
  • One focusing screen 5 is installed on the side of the cylindrical bush 4 and the other focusing screen 5 is located on the side of the flat disk 3.
  • the external diameter of the disk 3 is greater than that of the cylindrical bush 4 by the value ranging from 0.1 to 0.2 of the value of the interelectrode gap.
  • Figure 1 also illustrates:
  • h Used as a functional section of the primary-emission element is its thin edge projecting over the surface of the secondary-emission element by height h.
  • B is the induction of the static magnetic field.
  • Values h in magnetrons of different designs usually constitute from 0.1 to 0.2 of the value of the interelectrode gap which is equal to D - d 2 where D is the diameter of the magnetron anode and d - the external diameter of the secondary-emission element.
  • the design of the magnetron working part illustrated in Figure 2 is similar to that illustrated in Figure 1, the only difference being that the magnetron shown in Figure 2 comprises two secondary-emission elements whose end faces adjoin the end faces of the disk 3. Besides, the focusing screens 5 are installed on the side of the other end faces of the secondary-emission elements.
  • Illustrated in Figure 3 is the working part of a magnetron comprising five flat disks 3 and four cylindrical bushes 4 whose design is similar to that of the working part of the magnetron shown in Figure 1.
  • the only difference consists in that one focusing screen 5 ( Figure 3) is installed on the side of the last disk 3.
  • the primary-emission element can be made of several disks 3 depending on the type and desing of the magnetron and also on the excitation current value.
  • l (4 - 6) h where h is the height of the projecting edge of the disk 3 whose value is found from the formula (1).
  • the starting current can be reduced by no more than 10% its maximum value representing a sum of currents of separate disks 3 without consideration of their mutual screening.
  • Shown in Figure 4 is a section of a magnetron working part demonstrating the end faces of the cylindrical bush 4 made in the form of a truncated cone whose smaller base adjoins the end face of the disk 3.
  • the diameter of the larger base of the cone is an external diameter of the bush 4.
  • Figure 5 illustrates a section of the magnetron working part whose design is similar to that of the section shown in Figure 4.
  • the only difference consists in that the end faces of the adjacent flat disks 3 ( Figure 5) and bushes 4 adjoin each other through the flat cylindrical protective washer 6, each washer 6 being made of a thin foil of a refractory metal.
  • the thickness of the washer 6 exceeds that of the disk 3 at least five to ten times.
  • the washers 6 are made preferably of 15- to 30 ⁇ m thick tungsten.
  • the design of the magnetron working part illustrated in Figure 6 is similar to that of the magnetron working part shown in Figure 1.
  • the only difference consists in that the magnetron represented in Figure 6 comprises three disks 3, two bushes 4 and four washers 6.
  • the screens 5 are installed on the side of the first and the last disks 3 and the washers 6 are installed between the adjacent disk 3 and bush 4.
  • the washers 6 are installed with a purpose of protecting the disks 3 from possible deterioration as a result of chemical and physical interaction with the material of the bushes 4.
  • the protective washer 6 made of tungsten can be installed.
  • the magnetron of the present invention operates as follows:-
  • An anodic voltage is applied between the single-wire lead-in and the magnetron body (the lead-in and body are not shown in figures).
  • the magnetron excitation current is ensured by the field emission from the primary-emission element edge directed towards the anode 1.
  • the field emission is caused by the strong electric field created by the applied anodic voltage (the difference in potentials between the cathode and anode 1).
  • the electrons emitted by said element accelerating and changing the direction of their movement under the action of the microwave electromegnetic field, get partially on the secondary-emission element and expell the secondary electrons which in their turn, multiplying in an avalanch-like manner, ensure the main operating current of the magnetron.
  • the present invention makes it possible to ensure an instantaneous starting of the magnetron with the first pulse without preliminary heating-up of the cathode owing to the provision of the electric field intensity required for obtaining the field emission sufficient in its value for excitation of the magnetron.
  • the present invention can be used in radars, aircraft, sea ships, spacecraft, rockets, etc.

Landscapes

  • Microwave Tubes (AREA)
  • Manufacture And Refinement Of Metals (AREA)
EP92915517A 1992-04-15 1992-06-26 Magnetron Expired - Lifetime EP0593768B1 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
SU925043987A RU2007777C1 (ru) 1992-04-15 1992-04-15 Магнетрон
RU5043987 1992-04-15
PCT/RU1992/000131 WO1993021648A1 (en) 1992-04-15 1992-06-26 Magnetron

Publications (3)

Publication Number Publication Date
EP0593768A1 EP0593768A1 (en) 1994-04-27
EP0593768A4 EP0593768A4 (en) 1994-12-28
EP0593768B1 true EP0593768B1 (en) 1997-08-27

Family

ID=21605129

Family Applications (1)

Application Number Title Priority Date Filing Date
EP92915517A Expired - Lifetime EP0593768B1 (en) 1992-04-15 1992-06-26 Magnetron

Country Status (7)

Country Link
EP (1) EP0593768B1 (ko)
JP (1) JP2740793B2 (ko)
KR (1) KR100216657B1 (ko)
DE (1) DE69221873T2 (ko)
RU (1) RU2007777C1 (ko)
UA (1) UA7649C2 (ko)
WO (1) WO1993021648A1 (ko)

Families Citing this family (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5327094A (en) * 1992-12-11 1994-07-05 Litton Systems, Inc. Jitter suppression in crossed-field amplifier by use of field emitter
RU2115193C1 (ru) * 1994-03-22 1998-07-10 Владимир Ильич Махов Магнетрон
JP3390562B2 (ja) * 1994-06-28 2003-03-24 シャープ株式会社 マグネトロンおよび電子レンジ
US5874806A (en) * 1996-10-02 1999-02-23 Litton Systems, Inc. Passive jitter reduction in crossed-field amplifier with secondary emission material on anode vanes
RU2136076C1 (ru) 1998-01-08 1999-08-27 Махов Владимир Ильич Магнетрон
RU2183363C2 (ru) 1998-01-08 2002-06-10 Махов Владимир Ильич Свч-прибор м-типа
JP2003272537A (ja) * 2002-03-20 2003-09-26 Matsushita Electric Ind Co Ltd マグネトロン
JP2005056785A (ja) * 2003-08-07 2005-03-03 Matsushita Electric Ind Co Ltd マグネトロン
RU2494489C1 (ru) * 2012-02-10 2013-09-27 Общество с ограниченной ответственностью "Плутон Инвест" Магнетрон с безнакальным запуском со специальным активированием автоэлектронных катодов
CN107045970B (zh) * 2017-03-24 2019-02-26 西南交通大学 二次电子倍增阴极电子枪
CN109065427A (zh) * 2018-06-29 2018-12-21 安徽华东光电技术研究所有限公司 一种冷阴极磁控管的阴极

Family Cites Families (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR1306999A (fr) * 1961-11-25 1962-10-19 Cie Francaise De Micro Ondes Cathode froide pour magnétron
NL285091A (ko) * 1962-03-15
GB1023598A (en) * 1964-05-11 1966-03-23 English Electric Valve Co Ltd Improvements in or relating to magnetron cathodes
US3297901A (en) * 1964-06-05 1967-01-10 Litton Industries Inc Dispenser cathode for use in high power magnetron devices
GB2029632B (en) * 1978-09-02 1982-08-11 English Electric Valve Co Ltd Magnetrons
JPS5978427A (ja) * 1982-10-28 1984-05-07 Toshiba Corp マグネトロン
US4480235A (en) * 1983-01-18 1984-10-30 Varian Associates, Inc. Coaxial magnetron with improved starting

Also Published As

Publication number Publication date
KR940701581A (ko) 1994-05-28
WO1993021648A1 (en) 1993-10-28
UA7649C2 (uk) 1995-12-26
KR100216657B1 (ko) 1999-09-01
JPH06510629A (ja) 1994-11-24
JP2740793B2 (ja) 1998-04-15
EP0593768A4 (en) 1994-12-28
DE69221873T2 (de) 1998-01-29
DE69221873D1 (de) 1997-10-02
EP0593768A1 (en) 1994-04-27
RU2007777C1 (ru) 1994-02-15

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