CA2271253A1 - Electron gun assembly - Google Patents

Electron gun assembly Download PDF

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Publication number
CA2271253A1
CA2271253A1 CA 2271253 CA2271253A CA2271253A1 CA 2271253 A1 CA2271253 A1 CA 2271253A1 CA 2271253 CA2271253 CA 2271253 CA 2271253 A CA2271253 A CA 2271253A CA 2271253 A1 CA2271253 A1 CA 2271253A1
Authority
CA
Canada
Prior art keywords
electron gun
gun assembly
cylindrical
support
mount
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.)
Abandoned
Application number
CA 2271253
Other languages
French (fr)
Inventor
Steven Bardell
Alfred Christopher Thwaites
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
EEV 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 EEV Ltd filed Critical EEV Ltd
Publication of CA2271253A1 publication Critical patent/CA2271253A1/en
Abandoned legal-status Critical Current

Links

Classifications

    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01JELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J23/00Details of transit-time tubes of the types covered by group H01J25/00
    • H01J23/02Electrodes; Magnetic control means; Screens
    • H01J23/06Electron or ion guns
    • H01J23/065Electron or ion guns producing a solid cylindrical beam
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01JELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J2225/00Transit-time tubes, e.g. Klystrons, travelling-wave tubes, magnetrons
    • H01J2225/02Tubes with electron stream modulated in velocity or density in a modulator zone and thereafter giving up energy in an inducing zone, the zones being associated with one or more resonators
    • H01J2225/04Tubes having one or more resonators, without reflection of the electron stream, and in which the modulation produced in the modulator zone is mainly density modulation, e.g. Heaff tube

Landscapes

  • Electron Sources, Ion Sources (AREA)
  • Electrodes For Cathode-Ray Tubes (AREA)

Abstract

An electron gun assembly includes a cathode 1, control grid 5 located in front of it and a focus electrode 6. The control electrode 5 is integral with a cylindrical support 11 and formed of pyrolytic graphite. Similarly, the focus electrode 6 is integral with a cylindrical support 16 and is formed of molybdenum. The control grid 5 and fecus electrode 6 are mounted on a common mount 15 located behind the front face of the cathode 1, giving a simple structure having low thermally capacity and being mechanically robust.

Description

05/05 '99 16:08 FAX 01245 275114 GEC PATENT DEPT -~-~-~ KIRBY EADES GALE
f~003/014 Electron Gun Assembl This invention relates to an electron gun assembly and more particularly, but not exclusively, to an electron gun assembly suitable for use in inductive output tubes (IOTs).
An electron gun assembly includes a cathode from which an electron beam is generated at its front suzface and usually also includes one or more control electrodes to govern the profile of the electron beam so produced and to control its electron density. The present invention is concerned with an electron gun assembly in which both a control grid and focus electrode are included in front of the cathode.
According to the invention, there is provided an electron gun assembly comprising: a cathode, a control grid having a substantially cylindrical support and a focus electrode having a substantially cylindrical support, the control grid and focus electrode being in electrical contact with one another and being mounted on a comrnvn mount.
By providing a common mount for the control grid and focus electrode, instead of separate structures to support these two components, the amount of material used in the mounting arrangement is reduced, hence presenting a reduced thermal capacity.
This permits thermal equilibrium to be reached nacre quickly than would be case with a separately mounted control grid and focus electrode. Thus) the electron gun assembly reaches an operational state more quickly. fiurthermore, the invention provides a simple, mechanical robust construction which also occupies a smaller volume within the vacuum envelope surrounding an electron gun. The comz~cton mount may consist of a single component or could be made up of several separate components which are joined together. The common 25 could be made up of several separate components which are joined together.
The common mount is preferably a complete annulus, but it could be interrupted at one or more places around its circumference. In one embodiment, the common mount is annular, having an axially extensive cylindrical part and a flange part extensive normal to the axis, the axis being parallel to the direction of the electron beam. The cylindrical supports may be fixed to the axially extensive part and/or the flange part of the common mount.
The substantially cylindrical supports of the control gnd and focus electrode also may be made as thin walled shells, the cylindrical configuration being m~hanically strong.
Hence) the supports also present a small thermal capacity such that the whole assembly reaches an operating condition quickly. The control grid and its support may be a single integral component, and similarly so may the focus electrode and its support.
In a preferred embodiment of the invention, the cylindrical supports for the control grid and for the focus electrode have sides which are parallel to one another but in other x 5 arrangements they may diverge. The cylindrical supports extend rearwardly behind the front face of the cathode such that in a preferred embodiment) the common mount is located behind the front face of the cathode. This arrangement is advantageous as it removes the influence of the mount structure from a region where it miight affect the profile of the electron beam generated at the front face of the cathode.
As the control grid and focus electrode are in electrical contact with one another at the common mount, they may be mounted directly one on the other, minimising the number of components required and simplifying the assembly. Spacer means may be included between at least two of the common mount) the grid support and the focus electrode support to achieve 05/05 '99 18:09 FAX 01245 275114 GEC PATENT DEPT ~~~ KIRBY EADES GALE l~
-3- '° P/61338/VPOW
the required spacing between these components. For example, the spacer means may comprise one or more packing washers, or separate spacers located around the periphery of one of the components.
The cylindrical supports may advantageously have ends which are substantially normal to the cylindrical walls of the supports although they could be configured so as to lie somewhere between the generally axially extensive direction of the main part of the cylindrical support and the preferred configuration lying in a plane transverse to the axial direction. T'he ends may then be the pacts of the cylindrical supports which are fixed to the convnon mount. In an alternative embodiment, the cylindrical supports may be fixed to the common mount via their cylindrical walls.
In a preferred arrangement, fixing means pass through both cylindrical supports to !"lx them to the common mount. This may reduce assembly time and improve accuracy in the relative positioning of the control grid and focus electrode. However) in other arrangements, they may be separately fixed to the common mount. In a preferred embodiment, a plurality of fixing members are distributed spatially around the cylindrical supports, for example) these could be screws passing through the supports, to fix them firmly against a receiving face on the common mount. Washers or sonic compliant member could be interposed between the cylindrical supports and mount or fining members. In other arrangements, a single fixing means may be provided, for example, as an annular clamp arrangement.
According to a feature of the invention, an electron beam tube arrangement includes an electron gun assembly in accordance with the invention.

05/05 '99 18:09 FAX 01245 275114 GEC PATENT DEPT i-~~ KIRBY EADES GALE
f~005/014 -'1- P/6133 8/VPO W
Some ways in which the invention may be performed are now described by way of example with reference to the accompanying drawings in which:
Figure 1 schematically illustrates an electron gun assembly in accordance with the invention;
Figure 2 schematically illustrates an electron beam tube arrangement which includes the electron gun assembly of Figure 1; and Figure 3 schematically illustrates part of another electron gun assembly in accordance with the invention.
With reference to Figure 1) an electron gun assembly comprises a cathode 1 having a curved front surface 2 from which, doting operation, an electron beam is generated along the longitudinal axis X-X. The cathode 1 is supported by a cylindrical tube 3 which in turn is mounted on an annular support plate 4. A control grid 5 of pyrolytic graphite is located in the front of the cathode 1 having a configuration which conforms to the shape of the front surface 2 of the cathode and being closely spaced therefrom. A focus electrode 6 is located adjacent the control grid 5 on the other side to the cathode x and comprises a cylindrical part 7 which is substantially parallel to the axis X-X and a portion 8 Elating outwa~i,ly away from the axial direction X-X. A plate 9 located in front of the focus electrode 6 is maintained at a higher potential than the cathode 1 and acts as an anode. A cathode heater 10, which may be potted, is located behind the cathode 1.

05/05 '99 16:10 FAX 01245 275114 GEC PATENT DEPT ~~~ KIRBY EADES GALE l~

-5- P/61338/VPO'W
The control grid 5 is supported by a substantially cylindrical support 11 which is integral with it, the components being manufactured as a shell of the correct profile in which the apertures in the control grid 5 are then cut. The cylindrical support 11 has a conical rearwardly extending portion 12 immediately adjacent the control grid 5 and continues as a substantially straight sided, axially parallel portion 13, giving a relatively rigid structure. The end of the cylindrical support 11 is turned outwardly to forrrt as a transversely extensive part 14 which is substantially normal to the axial part 13. The end 14 is mounted on a face of an annular mount 15 of Kovar, a material of low thermal expansivity.
The focus electrode 6 is of molybdenum and is a thin walled shell which is produced by spinning or pressing. It is integral with a substantially cylindrical support 16. The support 16 has a substantially straight-sided section arranged parallel to the axis X-X. The end of the cylindrical support 16 is turned outwardly as a transverse flange 17 which is located adjacent to the end 14 of the pyrolytic graphite shell 11. The focus electrode support 16 is also mounted on the mount 15. A plurality of screws 18, only two of which are shown) are distributed around the circumference of the annular mount 15 and pass through both the molybdenum support 16 of the focus electrode 6 at flange 17 and the pyrolytic graphite support 1 x of the control grid 5 at end x4.
The annular mount 15 is supported by as annular member 19 which is a Kovar spinning or pressing and includes a generally transverse portion 20 and axially extensive parts 21 and 22, the annular mount 15 being attached to the inner part 21 of the annular member 19.

05/05 '99 16:10 FAX 01245 275114 GEC PATENT DEPT -~-~-~ KIRBY EADES GALE

w The electron gun assembly is included within a vacuum envelope which comprises a rearward portion 23 which is connected via vacuum seal to the annular support plate 4 of the cathode support tube 3. A conical ceramic cylinder 24 is brazed to the other side of the annular support plate 4 and to one surface of the cylindrical member 19. A
second conical ceramic cylinder 25 is brazed to the other surface of the cylindrical member 19 at one end and at its other end to a vacuum tight seal arrangement 26 which includes annular flanges 27 and 28 and a ceramic balance ring 29 located adjacent the anode plate 9.
Figure 2 schematically shows an IOT having an electron gun~ssembly as shown in Figure 1 and further includes an input resonant cavity 30 which is annular and generally surrounds the electron gun assembly,. drift tube 31 and an output cavity 32 from which an amplified output signal is extracted via coupling means 33.
With reference to Figure 3, in part of another electron gun assembly) a common mount 34 comprises an annular rCovar member having a cylindrical axially extensive part 35 and a flange pan 36 normal to the axis. The cylindrical walls 37 and 38 of the grid support and focus electrode support respectively are fixed by a plurality of screws) one of which 39 is shown, to the axially extensive part 35. Packing washers 40 and 41 are located between the common mount 34 and walls 37 and 38, the latter being in clectrical~ontact with one another.

Claims (20)

1. An electron gun assembly comprising: a cathode, a control grid having a substantially cylindrical support and a focus electrode having a substantially cylindrical support, the control grid and focus electrode being in electrical contact with one another and being mounted on a common mount.
2. An electron gun assembly as claimed in claim 1 wherein the common mount is located behind the front face of the cathode.
3. An electron gun as claimed in claim 1 or 2 wherein the common mount is substantially annular.
4. An electron gun as claimed in claim 1, 2 or 3 wherein the cylindrical supports of the control grid and the focus electrode include end parts which are substantially normal to the cylindrical parts of the supports.
5. An electron gun assembly as claimed in claim 4 wherein the end parts of the cylindrical supports are fixed to the common mount.
6. An electron gun assembly as claimed in any preceding claim wherein fixing means pass through both the cylindrical supports to fix them on the common mount.
7. An electron gun assembly as claimed in claim 6 wherein the fixing means comprises a plurality of fixing members distributed spatially around the cylindrical supports.
8. An electron gun assembly as claimed in claim 6 or 7 wherein the fixing means pass through the cylindrical walls of the supports.
9. An electron gun assembly as claimed in any proceeding claim wherein the common mount is supported by a mount support which is extensive through a vacuum envelope within which the electron gun assembly is contained.
10. An electron gun assembly as claimed in claim 9 wherein the mount support is substantially cylindrical and comprises an axially extensive portion and a transversely extensive portion, the transversely extensive portion being extensive through the vacuum envelope.
11. An electron gun assembly as claimed in claim 9 or 10 wherein the mount support comprises a Kovar spinning or pressing.
12. An electron gun assembly as claimed in any of claims 9 to 11 wherein the vacuum envelope comprises a ceramic wall through which the mount support is extensive.
13. An electron gun assembly as claimed in any preceding claim wherein a voltage is applied to the mount support to maintain the potentials of the focus electrode and the control grid.
14. An electron gun assembly as claimed in any preceding claim wherein the control grid is of pyrolytic graphite.
15. An electron gun assembly as claimed in any preceding claim wherein the focus electrode is of molybdenum.
16. An electron gun assembly as claimed in any preceding claim wherein the control grid is integral with its cylindrical support.
17. An electron gun assembly as claimed in any preceding claim wherein the focus electrode is integral with its cylindrical support.
18. An electron gun assembly as claimed in any preceding claim and including spacer means between at least two of the common mount, the grid support and the focus electrode support.
19. An electron gun assembly as claimed in any preceding claim wherein the common mount is annular, having an axially extensive cylindrical part and a flange part extensive normal to the axis.
20. An electron beam tube arrangement including an electron gun assembly as claimed in any preceding claim.
CA 2271253 1998-05-09 1999-05-07 Electron gun assembly Abandoned CA2271253A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB9809819.7 1998-05-09
GBGB9809819.7A GB9809819D0 (en) 1998-05-09 1998-05-09 Electron gun assembly

Publications (1)

Publication Number Publication Date
CA2271253A1 true CA2271253A1 (en) 1999-11-09

Family

ID=10831652

Family Applications (1)

Application Number Title Priority Date Filing Date
CA 2271253 Abandoned CA2271253A1 (en) 1998-05-09 1999-05-07 Electron gun assembly

Country Status (3)

Country Link
EP (1) EP0957505A3 (en)
CA (1) CA2271253A1 (en)
GB (2) GB9809819D0 (en)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6664720B2 (en) 2001-04-23 2003-12-16 L-3 Communications Corporation Temperature compensated gun
GB2386246B (en) * 2001-11-01 2005-06-29 Marconi Applied Techn Ltd Electron beam tube apparatus

Family Cites Families (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2975315A (en) * 1957-03-13 1961-03-14 Rauland Corp Cathode-ray tube
US3500110A (en) * 1967-08-23 1970-03-10 Raytheon Co Noncurrent intercepting electron beam control element
GB1353547A (en) * 1970-06-29 1974-05-22 Varian Associates Electron tube
US3983446A (en) * 1971-07-06 1976-09-28 Varian Associates Gridded convergent flow electron gun for linear beam tubes
US3967150A (en) * 1975-01-31 1976-06-29 Varian Associates Grid controlled electron source and method of making same
US4748369A (en) * 1986-04-10 1988-05-31 Star Microwave Electron gun assembly useful with traveling wave tubes
GB2271020A (en) * 1992-09-24 1994-03-30 Eev Ltd Electron gun arrangements
GB2287579B (en) * 1994-03-16 1997-05-07 Eev Ltd Electron gun arrangements
GB9806129D0 (en) * 1998-03-24 1998-05-20 Eev Ltd Electron beam tubes

Also Published As

Publication number Publication date
GB9910501D0 (en) 1999-07-07
EP0957505A2 (en) 1999-11-17
EP0957505A3 (en) 2002-07-31
GB2337152A (en) 1999-11-10
GB9809819D0 (en) 1998-07-08

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