EP0862198A2 - Magnetron avec anode plate - Google Patents

Magnetron avec anode plate Download PDF

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Publication number
EP0862198A2
EP0862198A2 EP98301106A EP98301106A EP0862198A2 EP 0862198 A2 EP0862198 A2 EP 0862198A2 EP 98301106 A EP98301106 A EP 98301106A EP 98301106 A EP98301106 A EP 98301106A EP 0862198 A2 EP0862198 A2 EP 0862198A2
Authority
EP
European Patent Office
Prior art keywords
interaction space
magnetic
pair
cathode
magnetic field
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.)
Granted
Application number
EP98301106A
Other languages
German (de)
English (en)
Other versions
EP0862198A3 (fr
EP0862198B1 (fr
Inventor
Tetsuya Ide
Keiichiro Uda
Seiki Yano
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.)
Sharp Corp
Original Assignee
Sharp Corp
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Filing date
Publication date
Application filed by Sharp Corp filed Critical Sharp Corp
Publication of EP0862198A2 publication Critical patent/EP0862198A2/fr
Publication of EP0862198A3 publication Critical patent/EP0862198A3/fr
Application granted granted Critical
Publication of EP0862198B1 publication Critical patent/EP0862198B1/fr
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
    • H01J23/10—Magnet systems for directing or deflecting the discharge along a desired path, e.g. a spiral path
    • 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
    • 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
    • H01J25/60—Magnetrons, i.e. tubes with a magnet system producing an H-field crossing the E-field with an electron space having a shape that prevents any electron from moving completely around the cathode or guide electrode; Linear magnetrons

Definitions

  • the present invention relates to a plate-type magnetron applied to high-frequency heating devices such as microwave ovens etc., in particular, relating to a multi-purpose plate-type magnetron which efficiently provides microwaves having a desired power and frequency.
  • a magnetron is a crossed-field device in which magnetic fields and electric fields are produced orthogonally to each other in the interaction space of an electron tube, and the oscillation modes are of two types, namely, the A-type oscillation and the B-type oscillation.
  • ⁇ is the mass of electron and e is the charge of an electron, hence the constant ⁇ is theoretically 10,650, but empirically, has a value from 10,000 to 13,000.
  • Fig.1 is a diagram showing a conventional cylinder type magnetron configuration.
  • a cylindrical anode 21 has a plurality of vanes 22 extending radially toward its center, forming cavity resonators.
  • a cathode 23 is provided on the central axis of the cylindrical anode thus defining the interaction space between cathode 23 and vanes 22.
  • anode 21 Provided on the top and bottom ends of anode 21 are pole pieces 24, each being attached in close contact with a magnet 26 having a yoke 25.
  • a magnet 26 having a yoke 25.
  • radiating plates 27 Provided between anode 21 and yoke 25 are radiating plates 27 for releasing heat generated by anode dissipation. This anode dissipation will arise when the electrons emitted from cathode 23 and accelerated by the anode voltage collide with anode 21.
  • a pair of electrodes (end hats) 30 are provided across, or at right angles with the direction of the magnetic field, sandwiching this interaction space.
  • a negative voltage is applied to these end hats 30, so that the electrons are confined within the interaction space.
  • a thermionic cathode is predominantly used at present.
  • a thermionic cathode is a cathode in which thermionic emission provides the source of electrons.
  • Thermionic emission is the mechanism for emitting electrons over the potential barrier at the material surface by heating the material up to a temperature from 1500 to 2500°K so as to impart energy equal to or greater than the work function of the material to the free electrons in the conduction band.
  • Thermionic cathode is formed of a pure metal, or a metallic oxide, etc., but currently, a sintered type which is obtained by mixing a Ba compound (5BaO ⁇ 2Al 2 O 3 ⁇ CaO etc.) and a W powder and press-sintering the mixture, an impregnation type which is obtained by impregnating Ba compound in a molten state into porous W, are mainly used. Either of these has a high emission density of electrons and additionally has advantages that gases are emitted less during evacuation and it can be reactivated if it is exposed to the air because of the effect of barium aluminates used.
  • a cold cathode is a cathode which emits electrons based on field emission, instead of thermionic emission.
  • Field emission is a method of electron emission wherein a high electric field is applied at and in proximity to the material surface to lower the potential barrier at the surface so as to emit electrons, using the tunnel effect.
  • This cathode is called a cold cathode since it does not need to be heated, unlike the thermionic cathode.
  • the current-voltage characteristics can be approximated by the Fowler-Nodeheim formula.
  • Fig.2 shows a sectional view of the configuration of a cold cathode.
  • Emitter portions 90 made up of a metal or semiconductor such as Si etc.
  • the cold cathode has advantages over the thermionic cathode in that the operating temperature is lower than that of the thermionic cathode and a high current density can be obtained by providing them in an arrayed form.
  • Figs.3 and 4 are sectional and perspective views respectively, showing a plate-type magnetron employing a cold cathode.
  • a plate-type anode 41 shown in Fig.3 has a number of vanes 42 which are provided on and perpendicularly to a cathode 43 and a sole portion 51, defining cavity resonators.
  • sole portion 51 is at equi-potential with cathode 43, but indicates the portion which will not contribute to emission of electrons unlike the cathode 43.
  • Cathode 43 is arranged in the lower left portion of anode 41.
  • the space between anode 41 and sole 51-vanes 42 forms an interaction space.
  • a pole piece for forming a uniform magnetic field in the interaction space is attached to the magnet of the yoke, on either side of anode 41. This yoke has radiating plates 47 for releasing heat generated due to anode dissipation.
  • the thus emitted electrons travels under the influence of the magnetic field from magnets 46 towards the right in Fig.2, in the interaction space, following a cycloidal path in a similar manner as in a cylindrical magnetron. During travel these electrons give up energy to the cavity resonators, generating high-frequency electric fields, which are output as microwaves through a microwave output portion 49.
  • ⁇ -mode In the case of a magnetron using anode segments, it is possible to cause various modes of operation depending upon the number of the segments.
  • the mode mainly used in the B-type oscillation called ⁇ -mode, in which the phase difference between successive resonators is ⁇ radian and the interaction therebetween is the strongest.
  • magnetrons have extremely useful characteristics, i.e., very high oscillation efficiency, high power and low cost, there is a demand that magnetrons be applied to a variety of technical fields other than microwave ovens. Accordingly, there has been an important theme of how a multi-purpose magnetron can be realized which can be applied to these broadened fields, such as commutations, radar, electronic devices etc.
  • the present invention is configured as follows:
  • a plate-type magnetron comprises:
  • the second aspect of the invention resides in the plate-type magnetron having the above first feature, wherein the magnetic portion comprises: a pair of pole pieces arranged facing each other on both sides of the interaction space; and a pair of magnets which each are attached to the pole piece and are set in close contact with the yoke to form a magnetic coupling, wherein the magnets are adapted to move.
  • the third aspect of the invention resides in the plate-type magnetron having the above first feature, wherein the magnetic portion comprises: a pair of pole pieces arranged facing each other on both sides of the interaction space; and a pair of magnets which each are attached to the pole piece and are set in close contact with the yoke to form a magnetic coupling, and the pole pieces can be varied in length.
  • the fourth aspect of the invention resides in the plate-type magnetron having the above first feature, wherein the magnetic portion comprises: a pair of pole pieces arranged facing each other on both sides of the interaction space; and a pair of magnets which each are attached to the pole piece and are set in close contact with the yoke to form a magnetic coupling, and the yoke can be varied in length.
  • a plate-type magnetron includes:
  • the output power can be varied in accordance with change in the potential of the electrodes while the frequency can be varied in accordance with the distance between the magnets. Further, when a positive voltage is applied to the electrodes, it is possible to remove the electrons, which can disturb the oscillation, from the interaction space.
  • Fig.5 is a sectional view showing a plate-type magnetron in accordance with the present invention. As shown in Fig.5, this plate-type magnetron is composed of an anode 11, vanes 12, a cathode 13, pole pieces 14, a yoke 15, magnets 16 and end hats 20.
  • a pair of electrodes or end hats 20 facing each other, to which positive and negative potentials are applied.
  • a pair of pole pieces 14 for generating a required magnetic field in interaction space 18 are arranged facing each other, on the outer sides of end hats 20.
  • a pair of magnets 16 are provided on the outer sides of pole pieces 14. Magnets 16 have a yoke 15, which is disposed in contact with anode 11.
  • the elements which contribute to forming the magnetic field in interaction space 18 are magnets 16, pole pieces 14 and yoke 15, which are magnetically coupled with one another. These elements are called, as a whole, a magnetic portion.
  • magnets 16 are of a ferrite type and are affixed to the side walls of the housing. Since yoke 15 also serves as a radiating plate for releasing heat generated from anode dissipation, it is made of a galvanized iron material.
  • the gap of the magnetic portion (the gap-distance in the magnetic portion) affecting the magnetic field strength in interaction space 18 can be varied by providing pole pieces 14 and yoke 15 in the form of bellows so that a variation of 20 mm in the gap-distance in the magnetic portion can be achieved. Magnets 16 can also be moved with the change in this distance.
  • Anode 11 is one which is produced by the fabrication method of a plate-type magnetron anode disclosed in Japanese Patent Application Laid-Open Hei 8 No.315,742.
  • the gap-distance in the magnetic portion is set as desired by operating the bellows of pole pieces 14 and yoke 15 so that a desired magnetic field is formed in interaction space 18.
  • a voltage is applied in a similar manner as described for the conventional magnetron with reference to Fig.3
  • electrons are emitted from cathode 13 and travel in interaction space 18 under the influence of this magnetic field, following a cycloidal path.
  • these electrons give up energy to the cavity resonators, generating high-frequency electric fields. Accordingly, microwaves having a frequency and output power associated with the distance between the magnets or the adjusted amount of pole pieces 14 and yoke 15 will be extracted.
  • a positive or negative voltage can be selectively applied to end hats 20, and magnets 16 are adapted to move and so the yoke length and the pole-piece length can be varied so as to provide microwaves having a desired output power and frequency.
  • this plate-type magnetron is constructed such that the electrons which will disturb the oscillation are removed from the interaction space by the application of a positive voltage to end hats 20 and this voltage is changed so as to control the output power.
  • Magnets 16 are adapted to be movable and bellows-like pole pieces 14 and yoke 15 are adjusted to change the yoke length and the pole piece length, whereby the gap-distance in the magnetic portion is altered, thus controlling the frequency.
  • the anode voltage is set at 100 V
  • the magnetic field strength set at 1,360 Gauss the distance between the magnets set at 30 mm
  • the end hats set a voltage of -10V
  • an emission current of 2.1A flows and an output power of oscillation of 160 W (2.5 GHz) can be obtained.
  • microwaves having a frequency of 3.1 to 5.1 GHz with an output power of oscillation of 3 to 7 W can be obtained. Additionally, when a voltage of +10 V is applied to end hats 20, microwaves having a frequency 3.1 to 5.1 GHz with an output power of oscillation of 10 to 20 W, about the three times of the output power under the former conditions, can be produced.
  • the magnetic portion can be constructed so as to vary the magnetic field strength generated in the interaction space, it is possible to alter the oscillating frequency by changing the magnetic field strength.
  • the magnets, the length of the pole pieces, and the yoke length are adjusted so as to alter the magnetic field strength in accordance with the gap-distance in the magnetic portion, thus making it possible to change the frequency.

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  • Microwave Tubes (AREA)
EP98301106A 1997-02-28 1998-02-16 Magnetron avec anode plate Expired - Lifetime EP0862198B1 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
JP46532/97 1997-02-28
JP4653297 1997-02-28
JP04653297A JP3333421B2 (ja) 1997-02-28 1997-02-28 平板型マグネトロン

Publications (3)

Publication Number Publication Date
EP0862198A2 true EP0862198A2 (fr) 1998-09-02
EP0862198A3 EP0862198A3 (fr) 1998-11-11
EP0862198B1 EP0862198B1 (fr) 2002-05-08

Family

ID=12749909

Family Applications (1)

Application Number Title Priority Date Filing Date
EP98301106A Expired - Lifetime EP0862198B1 (fr) 1997-02-28 1998-02-16 Magnetron avec anode plate

Country Status (5)

Country Link
EP (1) EP0862198B1 (fr)
JP (1) JP3333421B2 (fr)
KR (1) KR100291396B1 (fr)
CN (1) CN1147909C (fr)
DE (1) DE69805238T2 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2006008541A2 (fr) * 2004-07-23 2006-01-26 Stenzel Security Limited Appareil electronique

Families Citing this family (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR20010009047A (ko) * 1999-07-07 2001-02-05 김현순 마이크로파 유전가열기 또는 유전가열기용 챔버내의 마이크로파전자파 밀도(전계강도) 증강방법
KR100721218B1 (ko) * 2000-06-07 2007-05-22 대우전자부품(주) 편향요크용 세퍼레이터
KR20040050264A (ko) * 2002-12-10 2004-06-16 삼성전자주식회사 마그네트론, 전자렌지 및 고주파가열기
JP2013069602A (ja) 2011-09-26 2013-04-18 Tokyo Electron Ltd マイクロ波処理装置および被処理体の処理方法
CN103151230B (zh) * 2012-12-11 2015-05-13 中国人民解放军国防科学技术大学 磁控管用长脉冲高转换效率阴极
CN108807116B (zh) * 2018-06-05 2021-02-02 电子科技大学 一种采用非对称磁路的微波炉用扁平化磁控管

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2496500A (en) * 1945-07-18 1950-02-07 Raytheon Mfg Co Electron discharge device
US3109123A (en) * 1962-03-15 1963-10-29 Raytheon Co Electron discharge devices with a sharp edged cathode
US3932820A (en) * 1973-07-06 1976-01-13 The British Secretary of State for Defense Crossed field amplifiers
FR2401509A1 (fr) * 1977-07-01 1979-03-23 Cgr Mev Dispositif de controle des parametres de fonctionnement d'un magnetron a puissance de sortie reglable
JPH06302428A (ja) * 1993-04-14 1994-10-28 Shin Etsu Chem Co Ltd 永久磁石可変磁場発生装置
EP0694948A2 (fr) * 1994-06-28 1996-01-31 SHARP Corporation Magnétron et four à micro-ondes
JPH09259777A (ja) * 1996-03-19 1997-10-03 Sharp Corp マグネトロン及びその駆動方法

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP3165342B2 (ja) * 1994-12-05 2001-05-14 シャープ株式会社 マグネトロン
JP3165343B2 (ja) * 1994-12-07 2001-05-14 シャープ株式会社 平板型マグネトロン用陽極及びその製造法

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2496500A (en) * 1945-07-18 1950-02-07 Raytheon Mfg Co Electron discharge device
US3109123A (en) * 1962-03-15 1963-10-29 Raytheon Co Electron discharge devices with a sharp edged cathode
US3932820A (en) * 1973-07-06 1976-01-13 The British Secretary of State for Defense Crossed field amplifiers
FR2401509A1 (fr) * 1977-07-01 1979-03-23 Cgr Mev Dispositif de controle des parametres de fonctionnement d'un magnetron a puissance de sortie reglable
JPH06302428A (ja) * 1993-04-14 1994-10-28 Shin Etsu Chem Co Ltd 永久磁石可変磁場発生装置
EP0694948A2 (fr) * 1994-06-28 1996-01-31 SHARP Corporation Magnétron et four à micro-ondes
JPH09259777A (ja) * 1996-03-19 1997-10-03 Sharp Corp マグネトロン及びその駆動方法

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
PATENT ABSTRACTS OF JAPAN vol. 095, no. 001, 28 February 1995 -& JP 06 302428 A (SHIN ETSU CHEM CO LTD), 28 October 1994, *
PATENT ABSTRACTS OF JAPAN vol. 098, no. 002, 30 January 1998 -& JP 09 259777 A (SHARP CORP), 3 October 1997, *

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2006008541A2 (fr) * 2004-07-23 2006-01-26 Stenzel Security Limited Appareil electronique
WO2006008541A3 (fr) * 2004-07-23 2006-06-01 Stenzel Security Ltd Appareil electronique

Also Published As

Publication number Publication date
DE69805238D1 (de) 2002-06-13
JPH10241585A (ja) 1998-09-11
KR19980071724A (ko) 1998-10-26
EP0862198A3 (fr) 1998-11-11
CN1192036A (zh) 1998-09-02
EP0862198B1 (fr) 2002-05-08
KR100291396B1 (ko) 2001-07-12
CN1147909C (zh) 2004-04-28
DE69805238T2 (de) 2002-11-07
JP3333421B2 (ja) 2002-10-15

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