US2668929A - Magnetron - Google Patents

Magnetron Download PDF

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Publication number
US2668929A
US2668929A US280245A US28024552A US2668929A US 2668929 A US2668929 A US 2668929A US 280245 A US280245 A US 280245A US 28024552 A US28024552 A US 28024552A US 2668929 A US2668929 A US 2668929A
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US
United States
Prior art keywords
anode
space charge
cathode
segments
magnetron
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
US280245A
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English (en)
Inventor
Elmer D Mcarthur
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.)
General Electric Co
Original Assignee
General Electric Co
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
Application filed by General Electric Co filed Critical General Electric Co
Priority to US280245A priority Critical patent/US2668929A/en
Priority to GB9151/53A priority patent/GB725357A/en
Priority to FR1079921D priority patent/FR1079921A/fr
Application granted granted Critical
Publication of US2668929A publication Critical patent/US2668929A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • 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

Definitions

  • My invention relates to electric discharge devices of the magnetron type.
  • the anode segments defining the cylindrical space charge chamber through which an electron-emitting cathode extends are shaped to provide interaction gaps between adjacent segments whose center portions nearer the ends of the anode segments with respect to the desired direction of rotation of the space charge around the cathode.
  • the space charge rotation is established by conventional orthogonally aligned static electric and magnetic fields.
  • This component produces a corresponding axial force on the in-phase useful electrons which is directed inwardly from the ends of the anode towards the center portion, thus bunching the useful space charge so that it traverses the leading center portions of the gaps.
  • the out-of-phase electrons are subjected to oppositely directed axial forces, thus. throwing them to the ends of the space charge chamber. of-phase electrons would otherwise cause cathode Due to their high kinetic energy the out- 2 backheating if they remained in the space charge chamber. At the same time, the useful in-phase portion of the space charge is retained for efficient operation.
  • FIG. 1 is a perspective view of a magnetron discharge device embodying my invention
  • Fig. 2 is an enlarged view of the anode segment arrangement of Fig. 1
  • Fig. 3 is a sectional view of another magnetron embodying my invention
  • Fig. 4 is an end view of the anode of Fig. 3
  • Fig. 5 is a development of the anode segments illustrating the configuration of the interaction gaps of Fig. 4
  • Fig. 6 is a similar development illustrating a modified gap configuration.
  • a magnetron device having a generally cylindrical evacuated glass envelope I having its open end sealed to a metallic base or header member 2.
  • An anode structure 3 which may suitably take the form of a rectangular copper block, has its base conductively secured to the header.
  • a central opening 4 through the thickness of the block and communicating with the upper surface of the block defines the resonant circuit.
  • conductive side portions 5 and 6 of the anode block on diametrically opposite sides of the opening 4 are spaced from each other at the upper portion of the block and are connected in circuit by the base portion of the block.
  • the facing portions of the anode segments 5 and 6 are shaped to define a cylindrical space charge chamber 1 between them commensurate in length with the block thickness together with interaction gaps 8 and 9 between the facing segments of portions 5 and 6 on diametrically oppo site sides of the space charge chamber 1.
  • An elongated cathode III which may suitably comprise a wire helix coated with electron-emitting alkaline earth oxides, is centrally disposed within the space charge chamber 1 and coaxial therewith. The ends of the cathode extend beyond the ends of the-space charge chamber so that the cathode is conductively supported between the ends of a pair of upright cathode support rods II which are insulatingly sealed through the metal header 2.
  • the cathode is entirely conventional and is adapted to provide electrons for the magnetron space charge when it is suitably heated, as by applying a heating current voltage across the ends of the support rods ll extending through the header.
  • a pair of conductive cathode end shields or collector electrodes 12 are respectively positioned near the opposite ends of the space charge chamber and are suitably supported by the cathode ends and by auxiliary support members l3 each connected between a support rod II and an adjacent end shield l2.
  • the shields are preferably shaped as disks of a diameter somewhat larger than that of the space charge chamber in order that electrons expelled from the chamber may be collected thereon.
  • An output coupling means 14 is employed to transfer the high frequency output ener y to a desired load.
  • the outer conductor l of a concentric transmissionline coupling section is conductively secured to the header 2 and the inner conductor" lit is insulatingly sealed through the header 2 and the base of anode block 3 in order to provide an inductive pickup loop within the anode opening 4.
  • the interaction gaps '8 and 9 between the opposing faces or segments of the anode portions '5 and 5 are not provided with straight gap-defining edges but instead have a chevron shape.
  • the apex of each chevron, a viewed from the cathode is positioned midway along the length of the gap and is directed in a counterclockwise direction of rotation about the cham- 9 her.
  • This direction of space charge rotation is provided in operation when a static magnetic field, such as may be supplied by the sole noid schematically represented by the coil il in l, is supplied through the space charge chamber 1 and coaxial therewith, and a radial electric field is supplied between the cathode and the anode by applying a positive voltage to the anode block A with respect to the cathode.
  • This space charge excites the resonant anode circuit in a conventional manner in that electrons in phase with the alternating electric field induced between the anode segments on opposite sides of gaps 8 and 9 give up part of their kinetic energy to the field.
  • the alternating electric field between the facing segments of the anode portions 5 and 6 on opposite sides of the gap 8 has a substantial component parallel to the space charge chamber axis.
  • the relative magnitude of this axial component as compared with the component in planes transverse to the space charge chamber axis depends upon the chevron apex angle.
  • the apex angle is approximately l50-
  • the half-lengths of the gap edges on either side of the midpoint of the gap are at an angle of with respect to the cathode axis and; the axial component of the total electric field is proportional to the sine of that angle.
  • the magnitude of the angle may vary, it is desirably less than in order that-a major proportion of the alternating electric field may b tangential to the. cathode axis for efiective ex- --citati'on of the output circuit.
  • this axial component of the alternating electric field is directed inwardly towards the center of the gaps or outwardly from the gap apex towards the end spaces depends upon the phase of the electrons crossing the gap.
  • the electrons cross the interaction gap substantially in phase with the electric field, that is, when the electrons travel from a positively charged edge of the gap to the negatively charged edge, the electrons must work against the field and give up part of their kinetic energy to the resonant output circuit of the magnetron.
  • the useful electrons are bunched near the center of the space charge chamber and do not tend to stray towards the end spaces beyond the thickness of the anode block.
  • out-of-phase electrons which arrive at gap 8 or 9 with a velocity component opposing the alternating' electric field across the gap are subject to an axial force directed towards the end spaces beyond the space charge chamber where they may be easily collected by collector electrodes l3 and I4. Removal of these electrons is especially desirable since they subtract energy from the resonant output system and, because of the increased velocity thereby gained, normally tend to return to the cathode Where they cause backheating.
  • an additional number of anode segments and hence additional number of chevron-shaped gaps may be employed without departing from the spirit of my invention, so long as the central portions of the gaps lead the end portions with respect to the desired direction of rotation of magnetron space charge in order to provide the axial component of the like anode block assembly it preferably made of superposed upper and lower disk members [9 and It.
  • a central opening 20 in the anode assembly provides a cylindrical space charge chamber in which a cathode 2 i, which may suitably take the form of an electron emitting cylindrical sleeve containing a thermionic heater within, is centrally disposed.
  • a plurality of hole and slot cavity resonators 22 are incorporated into the anode assembly which communicate through excitation slots within the central opening 20.
  • a series of anode segments 23 are spaced from each other by interaction gaps 24.
  • eight cavity resonators are employed, but of course, a greater or lesser number may be alternatively be employed.
  • each anode segment 23 are shaped to define chevron-shaped interaction gaps 24.
  • the central portion oi each gap that is, the mid-length portion, comprises the apex of the chevron which leads the end portions of the. gap with respect to a given direction of electron space charge. rotation around the space charge chamher 20.
  • Fig. 5 is a developed view of the anode segment 23 and interaction gaps 24 as viewed from the cathode.
  • Cathode end shields 25, shown in Fig. 3 and corresponding to the end shields I2 of Fig. 1, may be suitably employed to collect the unwanted electrons.
  • the gap configuration referred to herein as chevron-shaped be one in which the apex of the chevron is sharply defined.
  • the gaps 24 between the anode segments 23 may be more generally curved. It is important, however, that the curves all have their central portions leading their end portions with respect to the space charge direction, and hence may be considered as convex in that direction.
  • a magnetron anode structure comprising a plurality of anode segments of given length defining a cylindrical space charge chamber with adjacent edges of adjacent segments defining chevron-shaped interaction gaps.
  • a magnetron anode structure comprising a plurality of anode segments of given length defining a cylindrical space charge chamber with the segment edges defining chevron-shaped interaction gaps between adjacent segments, the apex of the gaps being midway between ends of the segments.
  • a magnetron discharge device comprising an elongated electron-emitting cathode extending along a given axis, a plurality of anode segments surrounding said cathode and defining a cylindrical. space charge chamber coaxial therewith with adjacent segments spaced from each other, and resonant circuit means interconnecting said segments, said segments defining chevron-shaped interaction gaps between adjacent segments.
  • a magnetron discharge device comprising an elongated electron-emitting cathode extending along a given axis, an anode structure comprising a plurality of spaced anode segments surrounding said cathode and defining a cylindrical space charge chamber coaxial therewith, resonant circuit means interconnecting said segments, said segments defining chevron-shaped interaction gaps between adjacent segments, and collector shields positioned near the ends of said space charge chamber.
  • a magnetron discharge device comprising an elongated electron-emitting cathode extending along a given axis, an anode block surrounding said cathode and defining a cylindrical space charge chamber coaxial therewith, said anode block incorporating a plurality of cavity resonators communicating with said space charge chamber and with the anode segments between said resonators defining a plurality of chevronshaped interaction gaps.
  • a magnetron discharge device comprising an elongated electron emitting cathode extending along a given axis, a plurality of anode segments surrounding said cathode and defining a cylindrical space charg chamber coaxial therewith, and resonant circuit means interconnecting said segments, said segments defining aligned chevron-shaped interaction gaps between adjacent segments with the apex of each chevron-shaped gap directed in a given direction around a circumference of the space charge chamber.

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US280245A 1952-04-03 1952-04-03 Magnetron Expired - Lifetime US2668929A (en)

Priority Applications (3)

Application Number Priority Date Filing Date Title
US280245A US2668929A (en) 1952-04-03 1952-04-03 Magnetron
GB9151/53A GB725357A (en) 1952-04-03 1953-04-02 Improvements in and relating to magnetrons
FR1079921D FR1079921A (fr) 1952-04-03 1953-04-02 Magnétron

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US280245A US2668929A (en) 1952-04-03 1952-04-03 Magnetron

Publications (1)

Publication Number Publication Date
US2668929A true US2668929A (en) 1954-02-09

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US280245A Expired - Lifetime US2668929A (en) 1952-04-03 1952-04-03 Magnetron

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US (1) US2668929A (fr)
FR (1) FR1079921A (fr)
GB (1) GB725357A (fr)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2330942B (en) * 1997-11-04 1999-09-15 Samsung Electronics Co Ltd Magnetron

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2233482A (en) * 1938-05-31 1941-03-04 Rca Corp Anode tank circuit oscillator
US2412772A (en) * 1943-02-06 1946-12-17 Rca Corp Electron discharge device generator
US2477122A (en) * 1942-05-30 1949-07-26 Rca Corp Electron discharge device

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2233482A (en) * 1938-05-31 1941-03-04 Rca Corp Anode tank circuit oscillator
US2477122A (en) * 1942-05-30 1949-07-26 Rca Corp Electron discharge device
US2412772A (en) * 1943-02-06 1946-12-17 Rca Corp Electron discharge device generator

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Publication number Publication date
FR1079921A (fr) 1954-12-03
GB725357A (en) 1955-03-02

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