US2716711A - Magnetrons - Google Patents

Magnetrons Download PDF

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Publication number
US2716711A
US2716711A US263643A US26364351A US2716711A US 2716711 A US2716711 A US 2716711A US 263643 A US263643 A US 263643A US 26364351 A US26364351 A US 26364351A US 2716711 A US2716711 A US 2716711A
Authority
US
United States
Prior art keywords
cathode
pole piece
sheath
magnetic
anode
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
US263643A
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English (en)
Inventor
Thompson Frederick Charles
Esterson Maurice
Young Arthur James
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.)
Teledyne UK Ltd
Original Assignee
English Electric Valve Co Ltd
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 English Electric Valve Co Ltd filed Critical English Electric Valve Co Ltd
Application granted granted Critical
Publication of US2716711A publication Critical patent/US2716711A/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
    • 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
    • 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

  • This invention relates to magnetrons and more specifically to magnetrons of the so-called packaged type i. e. the type in which, in order to reduce the length of the air gap in the magnetic circuit, the discharge envelope is completed by members of magnetic material which also form part of the magnetic circuit so that, in effect, the magnetic poles are brought inside the envelope.
  • Fig. 2 is a similar view of a typical known packaged magnetron
  • Fig. 3 is a simplified sectional view showing the general pole piece and cathode structure arrangement of a magnetron embodying the present invention.
  • Fig. 1 the cathode 1, heated by an internal heater 2 is axially situated within a copper anode structure 3 having anode segments 4.
  • the structure 3 forms part of the discharge space envelope which is completed by flat copper side plates 5 and located between the poles 6 of the magnet system.
  • the magnetic gap is, as will be seen, a long one, being indicated by the dimension M.
  • the cathode structure is supported by support members 7 which enter the envelope from the side and extend more or less at right angles to the axis. End caps in the form of discs 8 prevent electrons leaving the anode cathode space and being collected by parts of the anode structure other than the anode segments.
  • the discs 8 thus serve to maintain a high conversion efficiency but their presence as well as that of the transverse support structure for the cathode, and that of the side plates 5, results in a long air gap M with consequent necessity to provide a heavy and bulky magnet system.
  • the air gap length M is much reduced with consequent ability to use a much stronger magnetic field with the same or a smaller magnet system by dispensing with the side plates 5, using the pole pieces 6 as part of the envelope structure, and supporting the cathode structure by means, generally designated 7a which run axially through a hole in one of the pole pieces instead of transversely as in Fig. 1.
  • the magnetic field in the space between anode and cathode shall be as uniform as possible and run as nearly as possible parallel to the cathode surface and this requirement strictly limits the maximum diameter which can be tolerated for the hole in the pole piece.
  • the lines of magnetic force in the anodecathode space should run as nearly as possible parallel to the axis of the anode and cathode and any departure from this ideal parallelism should be such as to make the field barrel-shaped and not in the other direction i. e.
  • This diode effect can grow seriously during the life of a magnetron for barium or other emissive material can migrate from the cathode to the cathode support tube and since the said cathode is usually mounted directly on the said tube the operating temperature of the latter is usually high enough for it to emit readily.
  • the present invention seeks to avoid or eliminate the above difficulties and defects.
  • a packaged magnetron wherein the cathode structure includes a cathode support member mounted within a hole in a pole piece is characterized in that said support member is mounted in a sheath of magnetic material at cathode potential and arranged to have good thermal insulation with respect to the cathode.
  • the cathode support member is a tube inserted into a sheath of magnetic material which is mounted within a hole in the pole piece and insulated therefrom, said sheath being thermally insulated from the cathode by a long conducting path.
  • Fig. 3 illustrates an embodiment of the invention.
  • the pole pieces 6a, 6b are alike and provided with axial holes which may be made as large in diameter as may be required.
  • the cathode which is indirectly heated by an internal heater, not shown, is on a cathode support tube 7.
  • the end of the support tube 7 is fitted into the end of a sheath 8 of magnetic material which is mounted in the pole piece 6a and is at cathode potential, being insulated from the said pole piece.
  • the sheath 8 is preferably shaped as shown being undercut at 81.
  • the surface of the sheath opposite the through the necessarily wall of the hole in the pole piece will be much cooler than the cathode and cathode support tube, and it will be obvious that it is unlikely to be appreciably contaminated by electron emitting material from the cathode.
  • the magnetic field can be made to approach closely to the ideal since the diameter of the hole in the magnetic material including pole piece and sheath within it may be made equal to or even less than that of the cathode despite that the pole itself has a large hole. Further the arrangement enables a mechanically strong cathode structure to be employed with little liability to becoming eccentric in use.
  • the lower pole piece 6b is fitted with an internal magnetic sheath 8a to ensure symmetry of the magnetic field about the transverse midplane of the anode, not shown.
  • the material of which the sheath 8 is made must be such as to ensure that it remains magnetic at its operating temperature. Such materials are commercially available.
  • a magnetron structure comprising an axial cathode structure having a cathode on a cathode support tube, an anode structure concentrically surrounding said cathode, a pair of magnetic pole pieces, one adjacent each end of said cathode and adapted to provide magnetic lines of force threading said cathode in a direction substantially parallel to the axis of said cathode, an evacuated envelope of which part is constituted by said anode structure and parts by said pole pieces, one of said pole pieces being tubular, and a sheath of magnetic material mounted within, and electrically insulated from, said one tubular pole piece, said cathode A support tube having its end inserted into the end of said sheath adjacent to said cathode supporting said cathode from said sheath and electrically connecting said cathode to said sheath.
  • a structure as claimed in claim 1 wherein the other of said pole pieces is also tubular and is substantially colinear with the first mentioned tubular pole piece and a second sheath of magnetic material fitted in said last mentioned tubular pole piece.

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US263643A 1951-01-11 1951-12-27 Magnetrons Expired - Lifetime US2716711A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB307460X 1951-01-11
GB291051X 1951-10-29

Publications (1)

Publication Number Publication Date
US2716711A true US2716711A (en) 1955-08-30

Family

ID=26259749

Family Applications (2)

Application Number Title Priority Date Filing Date
US263642A Expired - Lifetime US2727185A (en) 1951-01-11 1951-12-27 Magnetrons
US263643A Expired - Lifetime US2716711A (en) 1951-01-11 1951-12-27 Magnetrons

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Application Number Title Priority Date Filing Date
US263642A Expired - Lifetime US2727185A (en) 1951-01-11 1951-12-27 Magnetrons

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US (2) US2727185A (fr)
CH (1) CH307460A (fr)
FR (2) FR1047143A (fr)
GB (2) GB703172A (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2846618A (en) * 1953-01-26 1958-08-05 Litton Industries Inc Magnetron
US2899604A (en) * 1956-03-28 1959-08-11 Magnetrons

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
NL202111A (fr) * 1955-01-03
DE1086815B (de) * 1956-01-23 1960-08-11 Licentia Gmbh Kuehlsystem fuer Membran-anodenroentgenroehren

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB509102A (en) * 1937-10-08 1939-07-11 Electricitatsgesellschaft Sani Improvements in vacuum electric discharge apparatus
US2406276A (en) * 1942-11-13 1946-08-20 Gen Electric Electric discharge device
US2452077A (en) * 1944-01-19 1948-10-26 Raytheon Mfg Co Electric discharge device
US2463524A (en) * 1945-03-10 1949-03-08 Raytheon Mfg Co Electron discharge device
US2553425A (en) * 1948-03-13 1951-05-15 Raytheon Mfg Co Electron discharge device of the magnetron type

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
USRE22389E (en) * 1940-07-13 1943-11-02 Electron beam concentrating
US2419172A (en) * 1943-11-19 1947-04-15 Rca Corp Electron discharge device having coupled coaxial line resonators
US2497436A (en) * 1947-04-26 1950-02-14 Raytheon Mfg Co Electron discharge device

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB509102A (en) * 1937-10-08 1939-07-11 Electricitatsgesellschaft Sani Improvements in vacuum electric discharge apparatus
US2406276A (en) * 1942-11-13 1946-08-20 Gen Electric Electric discharge device
US2452077A (en) * 1944-01-19 1948-10-26 Raytheon Mfg Co Electric discharge device
US2463524A (en) * 1945-03-10 1949-03-08 Raytheon Mfg Co Electron discharge device
US2553425A (en) * 1948-03-13 1951-05-15 Raytheon Mfg Co Electron discharge device of the magnetron type

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2846618A (en) * 1953-01-26 1958-08-05 Litton Industries Inc Magnetron
US2899604A (en) * 1956-03-28 1959-08-11 Magnetrons

Also Published As

Publication number Publication date
GB703172A (en) 1954-01-27
FR1047143A (fr) 1953-12-11
GB706848A (en) 1954-04-07
US2727185A (en) 1955-12-13
FR1047586A (fr) 1953-12-15
CH307460A (fr) 1955-05-31

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