US2954498A - Reflex klystron - Google Patents

Reflex klystron Download PDF

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Publication number
US2954498A
US2954498A US733166A US73316658A US2954498A US 2954498 A US2954498 A US 2954498A US 733166 A US733166 A US 733166A US 73316658 A US73316658 A US 73316658A US 2954498 A US2954498 A US 2954498A
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United States
Prior art keywords
metallic
envelope
klystron
cylinder
ceramic
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Expired - Lifetime
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US733166A
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English (en)
Inventor
James O Hamilton
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AT&T Corp
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Bell Telephone Laboratories Inc
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Publication date
Application filed by Bell Telephone Laboratories Inc filed Critical Bell Telephone Laboratories Inc
Priority to US733166A priority Critical patent/US2954498A/en
Priority to BE577520A priority patent/BE577520A/fr
Priority to GB14899/59A priority patent/GB854584A/en
Application granted granted Critical
Publication of US2954498A publication Critical patent/US2954498A/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
    • H01J25/02—Tubes 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
    • H01J25/22—Reflex klystrons, i.e. tubes having one or more resonators, with a single reflection of the electron stream, and in which the stream is modulated mainly by velocity in the modulator zone
    • H01J25/24—Reflex klystrons, i.e. tubes having one or more resonators, with a single reflection of the electron stream, and in which the stream is modulated mainly by velocity in the modulator zone in which the electron stream is in the axis of the resonator or resonators and is pencil-like before reflection

Definitions

  • This invention relates to electron discharge devices and, more particularly, to velocity variation oscillators of the reflex type having a single external cavity resonator.
  • klystrons as they are more commonly known, comprise, in general, a cavity resonator through which an electron beam is projected and a bunching region adjacent thereto.
  • the cavity resonator includes two grids defining .a gap across which a radio frequency field is maintained for modulating the electron beam :by varying the velocity of electrons therein.
  • the repeller electrode reverses the direction of travel of the beam back toward the gap.
  • the density variations of the beam cause energy to be given up to the cavity resonator, thereby sustaining oscillations.
  • reflex klystron there are at least two types of reflex klystron; those having the resonant cavity within the envelope, and those having the resonant cavity external to and distinct from the envelope. In both types, a long predictable operating life is desirable.
  • the problem of obtaining such long life is complicated by the necessity of having electromagnetic wave permeable
  • the excitation of an external cavity is commonly accomplished through a ceramic or glass electromagnetic wave permeable window member positioned about the gap portion of the interaction region of the klystron. This glass ceramic member forms a portion of the envelope and is attached to other, normally metallic, portions thereof. To insure long life in a reflex klystron, those.
  • the means for mounting the internal components must be simple, strong, easily alignable, and accurate, and must consist of as few distinct Parts as possible. These mounting requirements are especiallyimportant in a device to be used at relatively high frequencies, since incremental variances have more effect where small components are in use, as with such high frequencies. It is, therefore, important that each component used in mounting the internal structure of the reflex klystron lend accuracy and strength, not only to the immediate component that it mounts, but to the whole of the internal structure and to the whole of the device.
  • a novel electron gun subassembly mounting member is utilized to relieve the stresses present at the junction between a metallic envelope portion which supports the anode of the gun arrangement and the electromagnetic wave permeable window surrounding the interaction region.
  • the anode is mounted in an aperture of a metallic envelope portion extending transverse to the klystron axis. To this metallic portion is aflix-ed the electromagnetic wave permeable Window. During operation the anode heats and expands, exerting pressure outward on the metallic portion and causing shear stresses at the junction of that portion with the window.
  • a hollow ceramic cylindrical member is affixed to the side of the metallic portion remote from the window. Also, in this embodiment, all of the components which require accurate positioning are so constructed that either a machined slip fit or a direct positioning by machine tool jig of each such component is possible.
  • a cylindrical ceramic member be mounted at one end to a metallic envelope portion and at the other end support the electron gun subassembly of a reflex klystron.
  • cornponents of a klystron requiring accurate alignment be so constructed as to allow positioning by either amachined slip "fit or by a machine'tool jig.
  • Fig. 1 is a cross-sectional representationof one specific embodiment of an external cavity reflex klystron in accordance with this invention
  • H p Fig. 2 is an exploded perspective view of various-elements of the embodiments of 'Fig. 1, including'particularly the electron gun subassembly and mounting, the anode, and the electron permeable window member.
  • the reflex klystron illustrated in Fig. 1 comprises an evacuated enclosure having a first hollow cylindrical metallic body member 11, closed at one end by a transversely extending end portion 12 having a machined circular aperture 13 located centrally therein.
  • a second hollow cylindrical metallic body member 14 At the other end of body member 11 and depending therefrom is welded or brazed a second hollow cylindrical metallic body member 14.
  • the lower portion of body member 14 is formed into a flange 15 lying in a plane transverse to the axis of the klystron 10 and is closed off by a platform 16, hermetically sealed thereto.
  • Circular platform 16 has a plurality of apertures 17 arranged therein at one radius about its center, with cylindrical ceramic pin insulators 18 depending from and hermetically sealed to the platform 16 at each aperture 17.
  • pin insulators 18 Hermetically sealing the ends of pin insulators 18 are metallic eyelet plates 19 projecting through the center of which are lead-in conductors 20. Each of conductors 20 is sealed to and supported by a vitreous bead, not shown, filling the center portion of each of pin insulators 18 and adhering thereto. Centrally located in platform 16 is an aperture 21. Hermetically sealed to the inner surface of the platform '16, surrounding aperture 21, is ceramic bushing 22. Bushing 22 is closed at its upper end by metallic washer 23 sealed thereto and supporting at its center an exhaust tubulation 24. Exhaust tubulation 24 projects through aperture 21 in platform 16 and is hermetically sealed to platform 16, ceramic bushing 22, and washer 23 by a glass bead, not shown.
  • Washer 23 has at one point at its circumference a projecting portion 25. Connected to portion 25 is a conductor 47 which is bent up and connected to one end of a getter assembly 26. The other end of getter 26 is connected to one of the lead-in conductors 20 so that it may be flashed by a potential across that lead-in conductor 20 and exhaust tubulation 24. Connected to the other lead-in conductors 20 are conductive means, not shown, for applying potentials to the various members of the device.
  • anode 38 Mounted within aperture 13 of end portion 12 of the envelope is an anode 38 having a machined circumference 44 which is an accurate slip fit within aperture 13.
  • the upper surface of a flange 45 on anode 38 is also machined to position the anode 38 axially in klystron 10 by bearing against the internal surface of end portion 12.
  • Anode 38 has a conical outer portion 39 and a centrally located frusto-conical inner portion 40. Extending longitudinally through inner portion 40 is bore 41 through which the electron beam passes during operation.
  • Portion 40 supports and positions at its upper end an electron permeable first grid 42, concentrically located with respect to the axis of klystron 10.
  • Window member 27 is a hollow cylindrical member, preferably of a ceramic material, and is positioned in manufacture by means of a jig and hermetically sealed at one end to metallic end portion 12.
  • a metallic end plate 28 Accurately positioned with respect to anode 38 at the other end of window member 27 and hermetically sealed thereto is a metallic end plate 28.
  • Centrally positioned in end plate 28 is an aperture 29 in which is mounted by a machine slip fit a grid housing member 30.
  • Grid housing member 30 is a. hollow, cylindrical, metallic member having a flange extending inwardly toward its axis at its lower end for mounting a second grid member 31.
  • Grid housing member 30 extends into the space enclosed by window 27 for accurately positioning second grid 31 in close proximity to grid 42. Grids 31 and 42 define therebetween the interaction region of device 10.
  • a flange 32 precisely machined for positioning and aligning discharge device 10 within its external cavity, not shown.
  • This external cavity is preferably of the type disclosed in an application by E. W. Houghton, Serial No. 733,092, filed May 5, 1958 ⁇
  • Extending through aperture 29 is a metallic member 33 having a shaped repeller 34 formed in its lower surface by a deep cup-like depression.
  • An annular flange 35 on member 33 is hermetically sealed to one end of a hollow ceramic cylindrical member 36 which positions member 33 with respect to anode 38 and which is hermetically sealed at its other end to the upper surface of end plate 28.
  • members 33 and 36 and end plate 28 may be positioned by means of jigs.
  • Ceramic member 36 accurately positions repeller 34 for cooperative association with respect to the interaction region formed by grids 31 and 42 and serves to insulate repeller 34 from the remaining portions of tube 10. Extending from the upper end of member 33 is a pin 37 to which may be applied the proper repeller potential, as well as modulating signals for effecting the operation of device 10.
  • a hollow cylindrical electron gun mounting member 50 which is a ceramic member of substantially the same size, shape, and material as ceramic window member 27.
  • a metallic washer 51 At the end of member 50 remote from portion 12 is a metallic washer 51 to which is aflixed, as by welding or brazing, a lower flanged portion 52 of a hollow cylindrical gun support member 53.
  • Member 53 is a metallic member mounted coaxially with body member 11 within gun mounting member 50 and has an upper portion 54 of lesser diameter than its main body portion.
  • This upper portion 54 advantageously supports by slip fit a hollow metallic cylinder 55 which mounts a beam forming electrode 56 at its uper extremity; alternately, beam forming electrode 56 may be made integral with member 55.
  • Beam forming electrode 56 is a metallic member of frusto-conical shape arranged coaxially with body member 11 and has a frusto-conical aperture 57 centrally located for allowing the passage of the electron beam during the operation of the device.
  • members 50, 53, and 55, and washer 51 are all supported by positioning jigs which accurately position beam forming electrode 56 relative to the other members.
  • a cathode sleeve 58 Accurately positioned by a slip fit within cylinder 55 is a cathode sleeve 58, a hollow metallic cylinder of lesser diameter and slightly lesser length than cylinder 55, abutting on electrode 56 and joined to cylinder 55 as by welding.
  • a hollow metallic cathode 59 Positioned within sleeve 58 is a hollow metallic cathode 59 which is mounted to member 58 by a plurality of cathode support wires 60, only one of which is shown.
  • Each support wire 60 is bent at its mid-point so that its two end portions are parallel and may be afiixed, as by brazing, to cathode sleeve 58 and cathode 59.
  • the upper end of cathode 59 has a concave, spherical electron emitting surface 61.
  • Cathode 59 is so positioned within cathode sleeve 58 by support wires 60 that the correct amount of clearance is obtained between emitting surface 61 and beam forming electrode 56 when cathode sleeve 58 abuts the latter member.
  • cathode 59, sleeve 58, and supports 60 are made from materials having coefficients of thermal expansion such that the cathode 59 will not shift relative to the cathode sleeve 58 as the parts become heated during operation of the device, support wires 60 being of material having low thermal conductivity.
  • a heater 62 supported through heater legs 46 by a ceramic heater support member 63 which closes the lower end of cathode sleeve 58 and is held therein by a metallic heater shield 64.
  • Shield 64 is basically a cup-like member fitting within and welded to cathode shield 58 and having tabs 43 crimped to hold heater support member 63.
  • Heater support leads 65 extend upwardly through holes in member 63 and back down through adjacent holes where they are Welded to heater legs 46 also extending through holes in member 63.
  • the spacing between grids 31 and 42 may be accurately set by measurement or, preferably, by mounting the tube 10 in a standard cavity and adjusting the grid spacing. After the grid spacing is determined, the spacing between electrode 56 and anode 38 is measured. Accurate adjustment of this spacing may be had inasmuch as support member 53, which has been fully annealed, may be deformed somewhat to give the desired spacing.
  • the electron beam initiated at emissive surface 61 of cathode 59 passes through anode 38 imparting heat thereto as an incident of its passage.
  • Anode 38 preferably a copper member, tends to expand as its temperature increases and exerts certain radial forces on end portion 12 wherein it is mounted.
  • the stresses imparted through the device by these forces and the means for overcoming them may be best understood through a contemplation of Fig. 2, which is an exploded view of end portion 12 of Fig. 1 and the various members mounted immediately thereto.
  • Fig. 2 is an exploded view of end portion 12 of Fig. 1 and the various members mounted immediately thereto.
  • a single ceramic cylinder 50 as a means for mounting the electron gun assembly not only allows the use of fewer members but gives a stronger, more accurate positioning than that employed by most prior art devices.
  • the use of a mounting device shaped as member 50 allows also the use of the two-step assembly process, previously described, which, with the all metallic-ceramic envelope, allows higher temperatures to be used in baking whereby cleaner tubes are obtained.
  • the metallic envelope portions are preferably of a material such as Kovar to facilitate the fabrication of coramic-metallic seals which may be baked out at high temperatures without injury to the various subassemblies which are assembled and baked separately.
  • An electron discharge device of the reflex klystron type comprising a symmetrical envelope, said envelope comprising a hollow cylinder having an apertured end portion extending transversely to the axis of said envelope, said cylinder completely surrounding a hollow cylindrical mounting member which is sealed to one side of said end portion, a cylindrical electromagnetic wave permeable member sealed to the other side of said end portion, an anode mounted Within the aperture of said portion, an electron gun mounted within said cylindrical mounting member, an apertured end plate affixed to one end of said cylindrical window, a grid housing unit mounted within the aperture of said end plate, a repeller electrode having a flange thereon extending through said aperture of said end plate, and a hollow cylindrical envelope portion affixed to said end plate and said repeller electrode, the inner diameter of said hollow envelope portion be ing equal to the diameter of the aperture in said end plate and the outer diameter of said cylindrical envelope portion being equal to the outer diameter of said flange.
  • An electron discharge device of the reflex klystron type comprising an envelope having a central axis, first, second, third and fourth hollow cylinders arranged coaxially in that order about said axis, said first cylinder mounted on said second cylinder, said second cylinder mounted on said third cylinder, a cathode mounted within and affixed to said first cylinder, a focusing electrode aflixed to one end of said second cylinder, said fourth cylinder having an apertured end portion extended transversely to said axis, said third cylinder being sealed to one side of said end portion, a cylindrical electromagnetic wave permeable window sealed to the other side of said end portion, an apertured end plate aflixed to one end of said cylindrical window, an apertured anode mounted within the aperture of said end portion, a first grid mounted within the aperture of said anode, a second grid mounted within the aperture of said end plate, a repeller electrode having a flange thereon, and a cylindrical enve lope portion affixed on one end

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US733166A 1958-05-05 1958-05-05 Reflex klystron Expired - Lifetime US2954498A (en)

Priority Applications (3)

Application Number Priority Date Filing Date Title
US733166A US2954498A (en) 1958-05-05 1958-05-05 Reflex klystron
BE577520A BE577520A (fr) 1958-05-05 1959-04-09 Klystron réflexe.
GB14899/59A GB854584A (en) 1958-05-05 1959-05-01 Improvements in or relating to electron discharge devices of the reflex klystron type

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US733166A US2954498A (en) 1958-05-05 1958-05-05 Reflex klystron

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US2954498A true US2954498A (en) 1960-09-27

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BE (1) BE577520A (fr)
GB (1) GB854584A (fr)

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2468141A (en) * 1944-10-12 1949-04-26 Raytheon Mfg Co Electron discharge device
US2605442A (en) * 1948-03-19 1952-07-29 Sylvania Electric Prod Electron discharge device
US2629066A (en) * 1951-12-10 1953-02-17 Eitel Maccullough Inc Electron tube
US2840746A (en) * 1956-10-22 1958-06-24 Gen Electric Electric discharge device including improved anode structure
US2867747A (en) * 1953-01-09 1959-01-06 Eitel Mccullough Inc Electron tube
US2910612A (en) * 1957-06-28 1959-10-27 Raytheon Co Circuit employing reflex klystron with protective diode
US2911559A (en) * 1953-05-05 1959-11-03 Ericsson Telefon Ab L M Reflex klystron of the double-disc type

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2468141A (en) * 1944-10-12 1949-04-26 Raytheon Mfg Co Electron discharge device
US2605442A (en) * 1948-03-19 1952-07-29 Sylvania Electric Prod Electron discharge device
US2629066A (en) * 1951-12-10 1953-02-17 Eitel Maccullough Inc Electron tube
US2867747A (en) * 1953-01-09 1959-01-06 Eitel Mccullough Inc Electron tube
US2911559A (en) * 1953-05-05 1959-11-03 Ericsson Telefon Ab L M Reflex klystron of the double-disc type
US2840746A (en) * 1956-10-22 1958-06-24 Gen Electric Electric discharge device including improved anode structure
US2910612A (en) * 1957-06-28 1959-10-27 Raytheon Co Circuit employing reflex klystron with protective diode

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BE577520A (fr) 1959-07-31
GB854584A (en) 1960-11-23

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