US2489298A - Velocity modulation electron discharge device - Google Patents

Velocity modulation electron discharge device Download PDF

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Publication number
US2489298A
US2489298A US710336A US71033646A US2489298A US 2489298 A US2489298 A US 2489298A US 710336 A US710336 A US 710336A US 71033646 A US71033646 A US 71033646A US 2489298 A US2489298 A US 2489298A
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United States
Prior art keywords
cavity
cathode
electron beam
anode
velocity modulation
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Expired - Lifetime
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US710336A
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English (en)
Inventor
James M Lafferty
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General Electric Co
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General Electric Co
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Publication date
Priority to BE477379D priority Critical patent/BE477379A/xx
Priority to FR955784D priority patent/FR955784A/fr
Application filed by General Electric Co filed Critical General Electric Co
Priority to US710336A priority patent/US2489298A/en
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Publication of US2489298A publication Critical patent/US2489298A/en
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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 pertains to. electron" discharge devices, suchas, oscillators, amplifiers, or the like, employing a velocity modulated .beam of electrical particles and has forits object the provision of an improvedconstruction capable of substantially greater power output and substantially higher frequency than devices of the type hitherto known in theart.
  • the objects of the-invention are accomplished by constructing the discharge devicein such a manner that the geometry of ple of velocity modulation. of an electron beam for example constructions in which a moving electronbeam havinginduced periodic density variations along its length is caused'topass in the vicinity of a resonant circuit element, such as a cavity resonator in. such -manner that the density variations will induce and sustain oscillations in the resonantelement.
  • a resonant circuit element such as a cavity resonator in. such -manner that the density variations will induce and sustain oscillations in the resonantelement.
  • Such constructions have not been assatisfactory. as could be the. electrodes, the cavities and of the beam is symmetrical with" respect to an extended plane rather than to the axis of-a narrow electron beam as. in the constructions heretofore known.
  • the various; elements of the device may besoconstructedthat the elec tron beam prodesiredfor the aforesaidpurposes principally because the maximum power output and the 4 maximum frequency-obtainable have not alwaysbeen sufiicient to satisfy the progressively increasing demandsgof-the artfor generators and amplifiers of the highestpossiblepower output and highest possible frequency.
  • any such shortcomings may-be attributed largely to restrictionson-the sizean'd density of the electron beam imposedby the-geometrical configurations of the various electrodesand res-.
  • an electron beam of generally circular cross section emanates from a cathode of similarcross section and passes-axially through toroidal cavity resonators forming the resonant "circuit element of the device, theconstruction therefore being symmetrical with respect to the axis of the electron beam.
  • Fig. 1 is a schematic illustration ofthe construction heretofore common in the art
  • Fig.. 2 represents .in cross section 7 an electrical discharge device embodying the principles of the invention
  • Fig. 3 represents in cross section a view ofithe device taken along the line 3-3 of Fig.
  • Fig. 4 represents-a View of the device ofFigJZ'looking from the outputconnections into thelcavity resonatorsection of the device.
  • a velocity 'modulated electron discharge device of the reflex type which may include withinan evacuatedenvelope I, a cathode -2 having the" usual disk shaped active surface, a cylindrical focusingelectrode 3, a cavity resonso-ator'in the formbf 'a toroidal cavity 4 having a symmetrical arrangements impose geometric" limitations on thenet power output; Therefore;- it becomes desirable notonlyto provide a cavity construction which will permit a much greater amount ofelectron-curiient to flow past the'cav'ty central aperture there'through; a second cylindrical focusingfelectrode 5; and a reflecting anode 6.
  • a narrow electron beam of circular"crosssection may be caused to pass from thecathode it through the O electrode 3, the cavity 4, the second focusing electrode whereupon it is reflected by the anode 6 back through the central aperture in the cavity 4, whereupon it will excite resonant oscillations within the cavity 5
  • periodic density variation lengthwise of the beam will be induced in the beam after its first passage through the cavity 4 and that such density variation will sustain oscillations within the cavity 4 during the return of the beam to the cavity on its reversed motion.
  • electrostatic potentials may be applied to the various electrodes by any suitable means such as the battery 'I which, by means of the connections indicated, imposes with respect to the cathode a high positive potential on the cavity 4, a negative potential on the focusing electrode 3, a negative or slightly positive potential on the focusing electrode 5 and finally a negative potential on the reflecting anode 6.
  • Figs. 2 and 3 there is shown in Figs. 2 and 3, as one illustration of the inventive principles, an electron discharge device of the velocity modulation type employing reflex principles.
  • the device shown may comprise generally a preferably metallic hermetically sealed envelope 8 in the form of a parallelepiped or other geometrical shape having considerable extension in one plane such as the plane of Fig. 3.
  • a cathode 9 an accelerator anode structure comprisin the symmetrically positioned blocks I0 and II provided with a focusing grid comprising parallel Wires I2, a cavity resonator structure comprising the blocks I3 and I4 mounted integrally within the corresponding blocks of the accelerator electrode and having cavities I5 and I6 formed therein, and a reflecting electrode I'I.
  • a cavity resonator structure comprising the blocks I3 and I4 mounted integrally within the corresponding blocks of the accelerator electrode and having cavities I5 and I6 formed therein, and a reflecting electrode I'I.
  • all of these elements Will have considerable extension in the direction perpendicular to the plane of Fig. 2, for example they will be elongated to extend completely across the width of the envelope 8.
  • the cathode 9 may comprise any suitable structure which presents to the accelerator anode structure a concave cylindrical sector portion I8 capable of focusing electrons emanating from a thermionically active coating on the surface of portion I8 into the accelerator anode slot formed by the opposin surfaces of blocks I6 and H.
  • it may comprise the box-like structure I9 having the concave cylindrical sector portion I8 as an end Wall facing the accelerator anode structure.
  • the surface of portion I3 may be coated with any of the suitable thermionically emissive substances known in the art.
  • any suitable means for raising that surface to an electronically emissive temperature may be provided such as the heater wires 20 embedded within a ceramic or other insulating material 2
  • Suitable means for energizing the said heater wires may be provided such as a battery 22 connected to the heater by the externally accessible leads 23 and 24 extending through and insulated from the envelope by hermetic sealing beads 25 and 26 of glass or like material.
  • the cathode may be supported in insulating relationship to the envelope 8 by any suitable means such as the insulating wall 27 afiixed to the envelope 8 by means of the metallic clamps 28 spot welded or otherwise aiiixed to envelope 8.
  • the cathode 9 may be supported within suitable slots in the insulating wall 2'! and rigidly aflixed thereto by metallic clamps 29 spot welded or otherwise affixed to structure I9.
  • the blocks ID and I I comprising the accelerator anode structure may be directly affixed to the wall of envelope 8 in conducting relationship therewith by any suitable means such as by brazing or welding thereto. Since the major portion of the energy losses dissipated as heat by the device is dissipated in these accelerator anode blocks and the cavity blocks I3 and. I4, the construction indicated is particularly advantageous in that heat may be directly conducted to the metallic envelope 8 and thereby dissipated externally in order that the electrode structure may not operate at too high a temperature.
  • the focusing grid wires I2 may each be conductively affixed at their opposite ends to one of the anode blocks I0 and II and formed in a generally arcuate shape conforming closely to and generally concentric with the concave shape of the cathode.
  • the spacing between Wires I2 be small in relation to the distance from the grid wires to the cathode surface.
  • the distance between any two wires I2 is preferably less than one half the distance from those wires to the cathode surface.
  • this grid structure may be also formed of a mesh of mutually perpendicular wires in the manner'of grid constructions known in the art.
  • the dimensions of the interstitial space should however, be small by comparison with the distance from the grid to the cathode for optimum focusing effects.
  • the opposed surfaces of the anode blocks I0 and II will preferably be formed in such manner as to present a generally wedge shaped opening between the blocks formed by the opposing surfaces 30 and 3!. As is well understood in the art appropriate shaping of these surfaces as well as the concave surface of the cathode Will result in desired shaping of electron beam configuration.
  • the cavity blocks I3 and I4 may :be formed by any construction which presents cavities of the desired configuration necessary .to oscillate :at the desired frequencies.
  • they are shown as comprising blocks having cavities of semi-circular cross section extending laterally to the envelope and having laterally extending d gaps 32 and 33 j-uxtaposed to the electron beam hereby forming 'enirfgQfor communication 3 be eenfthespace in the cavities l5 and I6 and ,the regions ofthe electron beam.
  • the reflecting anode ll may comprise any suitable formwhich presents a concave surface 134 adapted to reflect and focus the electron beam 'fbaclr into thevi'cinity of the cavity gaps 32 and 1331
  • .fit is shown as comprising a :bar tendinglaterally'to the envelope and having cylindrical concave surface formed in the side resented to thecavityresonators.
  • ,That elecode or anode may be supported in insulating lationship tofitne envelope 8 by. any suitable "means such as the rod 35 welded thereto and extendin .throughsthe glass sealing head 36 in the envelope wall.
  • any combination thereof for the purpose of extracting useful energy from the cavities or for the purpose of introducing energy for amplification or like urposes, any
  • suitable means may be provided.
  • suitable coupling loops may be inserted within the cavity and attached to appropriate external coupling lines.
  • a wave guide may be coupled to the cavities through an iris or slot formed in the wall of the envelope adjacent; to one end of the cavities.
  • Such a means is shown for example in Fig. 3 and comprises a cylindrical wave guide or cavity resonator 3B hermetically attached to the external surface of the wall of the envelope 8 which has an appropriate slot-like opening 39 exposing the ends of the cavities to external view as indicated in Fig. 4.
  • and the outer conductor 42 may be provided for delivering energy derived from the wave guide to suitable external utiliziation circuits not shown.
  • the coaxial transmission line may be hermetically sealed :by a head 43 of glass or like vitreous material sealed across the outer conductor 42.
  • the resonant frequency of the cavities may be controlled and tuned by a cylindrical wave guide or cavity resonator 44 of variable length attached to the opposite wall of the envelope and juxtaposed to the other end of the cavities through an, iris or slot.4 5 uilmto the ll of .theen- 'v'eiepe at that so "6. in a manner similar to that offthe slot 39.
  • Thelen'gtl'i of this cylindrical wave gide may befcontrolled' and varied by "means or the""pis'ton;46.
  • the hermetic sealing "of the device at this point of connection between the wave guide 54 and the envelopaflthe glass window 41 maybe provided across the cross'section' of the cylindrical wave guide and hermetically sealing the same. It Will be understood that movement 0f the piston 46 in either direction[will result in a corresponding "change in the; inductive or capacitative properties ofthe cavities and thereby result in a desired change in he ueney. "Alternatively, the cavities "may be provided with a tuning system similar to that shown and claimed in my copending application Serial No,] 7 20, 250 filed January 4-, 1947. in the latter casejthe accelerating anode and. resonators will be tormed' by a laminated confstruction in thernannershown in the'mentioned application.
  • the "wave guide-like structure formed by cavities l5 and J6 operatehear' itscutofi' wave 'lengthso' that the phase w-ave' lengthalong the longitudinal direction of the structure] is long.
  • Thelength ofthe vities lfi and l6 isthen only a small fraction ""o phase wave length and as a result the high flif requency electric iield across the gaps 32-133 maintains a high percentage of its maximum cavities.
  • the cavity ection l5'l6 is made 70 electrical degrees in length and sections comprising guides 38-44 are 55 electrical degrees each, the electric field at the ends of the gaps 32 and 33 only drop to 82 per cent of the maximum value at the center.
  • An electrical discharge device of the reflex velocity modulation type comprising a pair of spaced cavity resonators, an elongated anode structure extending between said resonators, said anode structure having extending therethrough a longitudinally extending cavity resonator symmetrical relative to a longitudinal axis thereof and tuned along with said pair of resonators to the frequency of oscillation of said device, said anode structure also having a transverse passageway with an elongated cross section extending therethrough in a plane perpendicular to the axis of said last-mentioned resonator and communicating with said last-mentioned resonator, and means for directing a relatively wide and thin electron beam through said passageway to excite said resonators at said frequency comprising an elongated cathode and an elongated reflector electrode disposed on opposite sides of said anode structure and disposed substantially in the plane of said passageway.
  • An electrical discharge device of the reflex velocity modulation type comprising a pair of spaced cavity resonators, an elongated anode structure extending between said resonators, said anode structure having extending therethrough "tam at the center along' the entire lengthof the.
  • said anode structure also having a transverse passageway with an elongated cross section extend- "ing therethrough in a plane perpendicular to the axis of said last-mentioned resonator and communicating with said last-mentioned resonator, means for directing a relatively wide and thin electron beam through said passageway to excite said resonators at said frequency comprising an elongated cathode and an elongated reflector electrode disposed on opposite sides of said anode structure and disposed substantially in the plane of said passageway, and means for varying the resonant frequency of said cavity resonators comprising a tuning plunger movably mounted in one of said pair of cavity resonators.
  • An electrical discharge device of the reflex velocity modulation type comprising a pair of spaced cavity resonators, an elongated anode structure extending between said resonators, said ;anode structure having extending therethrough ;a longitudinally extending cavity resonator symmetrical relative along with said pair of resonaztors to a longitudinal axis thereof and tuned to (the frequency of oscillation of said device, said ⁇ way with an elongated cross section extending itherethrough in a plane perpendicular to the axis (of said last-mentioned resonator and communiecating with said last-mentioned resonator, and
  • means for directing a relatidelfy wide and thin wanode structure also having a transverse passageelectron beam through said passageway to excite said resonators at said frequency comprising an elongated cathode and an elongated reflector electrode disposed on opposite sides of said anode structure and disposed substantially in the plane of said passageway, the phase wave length of said last-mentioned resonator being of the order of 70 electrical degrees and the phase wave length of each of said pair of resonators being of the order of 55 electrical degrees whereby the high frequency electric field across said last-mentioned resonator where said passageway communicates with said last-mentioned resonator is a high percentage of its maximum value along the length thereof and efficient density modulation of said electron beam is obtained along its entire width.

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US710336A 1946-11-16 1946-11-16 Velocity modulation electron discharge device Expired - Lifetime US2489298A (en)

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Application Number Priority Date Filing Date Title
BE477379D BE477379A (xx) 1946-11-16
FR955784D FR955784A (xx) 1946-11-16
US710336A US2489298A (en) 1946-11-16 1946-11-16 Velocity modulation electron discharge device

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Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2567674A (en) * 1949-11-08 1951-09-11 Rca Corp Velocity modulated electron discharge device
US2653273A (en) * 1951-04-14 1953-09-22 Research Corp High-frequency amplifier
US2685046A (en) * 1949-11-01 1954-07-27 Rca Corp Magnetron
US2724072A (en) * 1950-12-18 1955-11-15 Raytheon Mfg Co Reflex klystron
US2825842A (en) * 1952-09-12 1958-03-04 Sperry Rand Corp Electron beam producing and focussing assembly
US2844756A (en) * 1950-12-29 1958-07-22 Philips Corp Electron discharge device with resonator
US2888599A (en) * 1953-10-05 1959-05-26 Varian Associates Electron discharge apparatus
US3432714A (en) * 1967-01-24 1969-03-11 Us Army Fast warmup cathode

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2259690A (en) * 1939-04-20 1941-10-21 Univ Leland Stanford Junior High frequency radio apparatus
US2293151A (en) * 1940-10-08 1942-08-18 Rca Corp Resonant cavity device
US2410822A (en) * 1942-01-03 1946-11-12 Sperry Gyroscope Co Inc High frequency electron discharge apparatus
US2410863A (en) * 1940-03-05 1946-11-12 Emi Ltd Electron discharge device
US2413963A (en) * 1942-09-17 1947-01-07 Gen Electric Ultra high frequency control system
US2414785A (en) * 1942-01-29 1947-01-21 Sperry Gyroscope Co Inc High-frequency tube structure

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2259690A (en) * 1939-04-20 1941-10-21 Univ Leland Stanford Junior High frequency radio apparatus
US2410863A (en) * 1940-03-05 1946-11-12 Emi Ltd Electron discharge device
US2293151A (en) * 1940-10-08 1942-08-18 Rca Corp Resonant cavity device
US2410822A (en) * 1942-01-03 1946-11-12 Sperry Gyroscope Co Inc High frequency electron discharge apparatus
US2414785A (en) * 1942-01-29 1947-01-21 Sperry Gyroscope Co Inc High-frequency tube structure
US2413963A (en) * 1942-09-17 1947-01-07 Gen Electric Ultra high frequency control system

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2685046A (en) * 1949-11-01 1954-07-27 Rca Corp Magnetron
US2567674A (en) * 1949-11-08 1951-09-11 Rca Corp Velocity modulated electron discharge device
US2724072A (en) * 1950-12-18 1955-11-15 Raytheon Mfg Co Reflex klystron
US2844756A (en) * 1950-12-29 1958-07-22 Philips Corp Electron discharge device with resonator
US2653273A (en) * 1951-04-14 1953-09-22 Research Corp High-frequency amplifier
US2825842A (en) * 1952-09-12 1958-03-04 Sperry Rand Corp Electron beam producing and focussing assembly
US2888599A (en) * 1953-10-05 1959-05-26 Varian Associates Electron discharge apparatus
US3432714A (en) * 1967-01-24 1969-03-11 Us Army Fast warmup cathode

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FR955784A (xx) 1950-01-19
BE477379A (xx)

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