US2813994A - Indirectly heated cathode structure for magnetrons - Google Patents

Indirectly heated cathode structure for magnetrons Download PDF

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Publication number
US2813994A
US2813994A US543974A US54397455A US2813994A US 2813994 A US2813994 A US 2813994A US 543974 A US543974 A US 543974A US 54397455 A US54397455 A US 54397455A US 2813994 A US2813994 A US 2813994A
Authority
US
United States
Prior art keywords
heater
cathode
insulator
tube
housing
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
US543974A
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English (en)
Inventor
Young Arthur James
Pickering Alan Hugh
Crook Archie Watson
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
Priority claimed from GB4555A external-priority patent/GB783294A/en
Application filed by English Electric Valve Co Ltd filed Critical English Electric Valve Co Ltd
Application granted granted Critical
Publication of US2813994A publication Critical patent/US2813994A/en
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
    • H01J23/04—Cathodes
    • H01J23/05—Cathodes having a cylindrical emissive surface, e.g. cathodes for magnetrons

Definitions

  • This invention relates to indirectly heated cathode structures for magnetrons and more particular to such cathode structures of the kind in which the cathode heater is within a cathode-carrying tubular or similar box which is, when the magnetron isin use, so positioned as to be subjected to high frequency fields.
  • Figure 1 is a schematic sectional elevation showing a typical known form of magnetron cathode structure
  • Figure 2 is a view similar to Figure 1 of one embodiment of the present invention
  • Figure 3 is a part view of a modification
  • Figure 4 is a part of another modification.
  • this shows the indirectly heated cathode structure of a multiple cavity magnetron having the usual anode block with the cathode at the axis thereof.
  • the anode block is only partly represented at 1.
  • Insulated from the anode block and carried thereby so as to extend radially inwards are two metal carrier rods 2 and 3 whose attachment to the anode block are not shown in the figure. These carrier rods also form external connections to the cathode heater as will be seen later.
  • Carried by the carrier rods 2 and 3 are two metal discs 4 and 5 of which the former forms one closure and piece of a metal tube 6 on the surface of which is electron emissive material (not separately shown) so that the tube 6 forms the cathode proper.
  • the cathode heater is in the form of a helical winding 9 concentrically within the box structure constituted by the parts 4 to 8 which is connected to the discs 4 and 5 at the points 10 and 11.
  • the heater is of wire coated with alumina or some similar material, the purpose of which is to insulate the heater turns from one another and also from the interior of the cathode tube 6.
  • a magnetron cathode structure wherein a cathode heater is contained within a cathode-carrying box-like housing which is partially conductive but has a metallic end piece and an insulator insulating said end piece from the remaining metal parts of the housing is provided with means for providing additional capacity between said end piece and said remaining metal parts of said housing.
  • the means for providing the additional capacity may take any of a variety of diiferent forms.
  • the end turns of the heater adjacent an end insulator forming part of the housing is encircled by a metallic tube electrically and mechanically united with a metallic end plate of the housing to which said end of the heater is connected and which is insulated from the rest of the housing.
  • a skirt member is electrically and mechanically connected to a cathode tube forming part of the housing near an end which incorporates an insulator, said skirt member extending over the insulator towards a metallic end plate of the housing on the other side of said insulator and to which the adjacent end of the heater is connected.
  • a metal disc-like member apertured to pass the connection from the heater to the metallic end plate adjacent the end insulator is placed over said insulator on the side thereof remote from said metallic end plate and is connected to the cathode tube.
  • the invention is not limited to the production of any particular value of additional capacity it is found in practice that the production of an additional capacity of the order of 5 to 10 pico-farads is satisfactory.
  • the inherent self capacity between the cathode tube 6 and the metallic end plate 5 of the housing is only of the order of 2 to 3 pico farads or thereabouts so that, in practice the invention involves more than doubling the capacity normally present at the point in question.
  • the invention operates by virtue of the fact that the increased capacity reduces the effective heater impedance for high frequency over at least the vulnerable length thereof but whether or not this theory of operation is correct and sufficient experiment has shown that a substantial practical advantage is obtained by the use of the invention.
  • Figures 1 and 2 there is provided a metallic tube 12 encircling the end turns of the heater 9 in the neighbourhood of the insulator 7, said tube being welded or otherwise mechanically and electrically united with the cap 8 and, therefore, with the metallic end plate 5 of the housing within which the heater is situated.
  • the heater of Figure 2 is of rather smaller diameter than that of Figure 1 and the insulator 7 thereof is of slightly different shape from the insulator 7 of Figure l in order that the tube 12 may be properly located safely out of contact with the heater turns embraced thereby.
  • the tube 12 is brought as close as is U practicable to the encircled turns of the heater 5 while avoiding risk of contact.
  • the pressure of the tube 12 provides the required additional capacity.
  • a metallic skirt 13 is welded or otherwise mechanically and electrically united with the cathode tube 6, said skirt clearing the cap 8 round the insulator 7 and extending almost to the end disc 3.
  • This skirt provides additional capacity between the disc 5 and the cathode tube 6.
  • a disc like member 14 apertured to pass the heater end connection to the connection point 11 is fitted over the insulator 7 on the side thereof remote from the metallic end plate 5 and is arranged to be in electrical connection with the cathode tube 6 so as to provide additional capacity be tween said tube and the end plate 5.
  • a magnetron cathode structure wherein a cathode heater is contained within a cathode-carrying box-like housing which is partially conductive but has a metallic end piece and an insulator insulating said end piece from the remaining metal parts of the housing, said magnetron cathode structure having means for providing additional capacity between said end piece and said remaining metal parts of said housing.
  • a magnetron cathode structure as claimed in claim 1 wherein a skirt member is electrically and mechanically connected to a cathode tube forming part of the housing near an end which incorporates an insulator, said skirt member extending over the insulator towards a metallic end plate of the housing on the other side of said insulator and to which the adjacent end of the heater is connected.

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  • Microwave Tubes (AREA)
US543974A 1955-01-03 1955-10-31 Indirectly heated cathode structure for magnetrons Expired - Lifetime US2813994A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB4555A GB783294A (en) 1955-01-03 1955-01-03 Improvements in or relating to indirectly heated cathode structures for magnetrons
GB2813994X 1955-09-12

Publications (1)

Publication Number Publication Date
US2813994A true US2813994A (en) 1957-11-19

Family

ID=32327992

Family Applications (1)

Application Number Title Priority Date Filing Date
US543974A Expired - Lifetime US2813994A (en) 1955-01-03 1955-10-31 Indirectly heated cathode structure for magnetrons

Country Status (3)

Country Link
US (1) US2813994A (enrdf_load_stackoverflow)
DE (1) DE1120608B (enrdf_load_stackoverflow)
NL (2) NL89999C (enrdf_load_stackoverflow)

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2414605A (en) * 1943-05-13 1947-01-21 Westinghouse Electric Corp Cathode mounting
US2510267A (en) * 1946-10-30 1950-06-06 Rca Corp Grid cathode assembly for cathoderay tubes
US2569847A (en) * 1949-04-08 1951-10-02 Eitel Mccullough Inc High-frequency tetrode with built-in capacitor

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
NL129021B (enrdf_load_stackoverflow) * 1942-05-01
BE470767A (enrdf_load_stackoverflow) * 1945-02-17
GB706848A (en) * 1951-01-11 1954-04-07 English Electric Valve Co Ltd Improvements in or relating to magnetrons

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2414605A (en) * 1943-05-13 1947-01-21 Westinghouse Electric Corp Cathode mounting
US2510267A (en) * 1946-10-30 1950-06-06 Rca Corp Grid cathode assembly for cathoderay tubes
US2569847A (en) * 1949-04-08 1951-10-02 Eitel Mccullough Inc High-frequency tetrode with built-in capacitor

Also Published As

Publication number Publication date
NL202111A (enrdf_load_stackoverflow)
NL89999C (enrdf_load_stackoverflow)
DE1120608B (de) 1961-12-28

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