US2485661A - Oscillation generator of the velocity modulation type - Google Patents

Oscillation generator of the velocity modulation type Download PDF

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Publication number
US2485661A
US2485661A US511094A US51109443A US2485661A US 2485661 A US2485661 A US 2485661A US 511094 A US511094 A US 511094A US 51109443 A US51109443 A US 51109443A US 2485661 A US2485661 A US 2485661A
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United States
Prior art keywords
grid
cathode
resonator
slot
electron
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Expired - Lifetime
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US511094A
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English (en)
Inventor
Roach Richard Greville
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International Standard Electric Corp
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International Standard Electric Corp
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Publication date
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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
    • H01J25/06—Tubes having only one resonator, without reflection of the electron stream, and in which the modulation produced in the modulator zone is mainly velocity modulation, e.g. Lüdi-Klystron
    • H01J25/08—Tubes having only one resonator, without reflection of the electron stream, and in which the modulation produced in the modulator zone is mainly velocity modulation, e.g. Lüdi-Klystron with electron stream perpendicular to the axis of the resonator

Definitions

  • This invention relates to oscillation generators of the velocity-modulation type which are intended to be tunable over a wide frequency range.
  • the greatest energy exchange between the resonator field and the beam is when the beam is projected across the field of the resonant chamber at a voltage anti-node.
  • the wavelenth is long since the frequency is low, and the current passes across a length of the resonant chamber over which the voltage amplitude is not greatly different from that at the anti-node.
  • An object of this invention is to provide an arrangement in which the conflicting conditions for utilising a velocity modulation tube at high and low frequencies set out in the last two preceding paragraphs are reconciled.
  • an oscillation generator of the Velocity modulation type is provided with means for automatically variably controlling the strength of the electron beam current in accordance with variations in operating frequency.
  • This means may comprise means for varying the cross-sectional area of the electron beam, for example, by varying the dimension of the beam parallel to the standing waves which interact with the beam to velocity modulate the latter, and the variation may be effected under the control of a factor determined by the desired operating frequency.
  • a long cathode is used and located parallel to the direction of the standing waves, for example, in the resonant chamber when such is used, and in front of this cathode a special retarding electrode is placed.
  • This special retarding electrode is so constructed that the control exerted thereby on the electrons leaving the cathode is strong at the end (ends if a double-ended system, e. g. a coaxial resonant chamber, is used) of the cathode and becomes progressively weaker, reaching its point of least control where it covers that point on the cathode opposite to the voltage anti-node.
  • a retarding electrode may for example be a grid of the well known variable mu type.
  • the bias on the grid is a factor determined by the desired operating frequency, and the bias is so controlled that at low frequencies the grid voltage is zero or only slightly negative, and current from the whole length of the cathode is used. On the other hand, at high frequencies a much larger negative voltage with respect to the oathode is applied to the grid, and, due to the varying control of the. grid along its length, current is automatically cut off .from those parts:of the.
  • variable mu grids normally are wire wound, the pitch of the Winding. changing.
  • the same effect may be obtained by using a slot grid, the width of the slotvarying along the length, or by other suitable arrangement.
  • the-grid may be'bowed; In this case the cathode to grid-spacing is made to vary-alongthe length ofthe grid.
  • the grid'in this case may also be of the variable pitch or slot width type or may be'formed with uniform wirespacingor slot widths.
  • Fig: 1 shows diagrammatically in perspective view the essential elements of an electron discharge tub'eofthe velocity. modulation type, for example'as described'in the Patent No. 2,320,860, embodying the present invention.
  • Fig. 2 shows various alternative constructions of the grid.
  • the resonator indicated by thereference number I,.is of the coaxial linetype provided with slots 2' inthe outer and inner conducting walls .3, vll respectively of .the. ohamber,.in alignmentalong a diameter.
  • the source ofelectrons shown as a:linear..cathode.5, which may be directly or indirectly heated, so as to provide a. rectangular beam of electrons to. pass through the slots 2.. Any other suitable source of electrons may be provided-for producing. a.wide
  • thisgrid ,1 comprises a bowedmetal .strip having therein a rectangular slot B andthe .grid is positioned so that the slot 8 is in alignment withthe slots :2 .of the :resonator and with the. cathode 5..
  • the frequency is varied byvaryingthe length of the coaxialline
  • the potential on the grid is-varied T as the operating wave-length Conditions is varied. For example, if the wave length is increased it is desired to increase the beam width and the grid 1 is made less negative with respect to the cathode 5 so that the grid in suppressing the. fiow of electrons is not so effective as for a more negative bias for the same distance of the grid from the .cathodeand the width of the electronbeam is thereby increased. In addition, due to the smaller negative potential the intensity of the. beam.
  • the accelerating voltage is decreased for an increase in wavelength, the change in bias on the grid tendstocompensate for the change in intensity of the beam due to the lower accelerating voltage and increasesthebeam width. Also the greater width .of'the beam allows a greater and more efiicientinteraction with the electric field of longer wave length, than if the beam had a constant width.
  • the point ofileast controls of z the grid. is :looatedv opposite to the location of. the. voltage anti-node; off the: shortest wavelengthtorbeused; and .the type; oflgrid used. is .of 1 the. symmetrical :typesfor: example as shown in Fig. l or-at'B and1G inFig. 2.
  • a wire wound grid of equal pitch but bowed may be used.
  • the bowed types of grid need not necessarily be in the form of an arc of a circle. Alternatively they may have any desired curvature to suit conditions and may for example be linear and inclined to the cathode at any desired angle.
  • a desired variation of grid control on the electron stream may be obtained by a suitable combination of slot shape or in the case of wire wound grids, of pitch and curvature of the grid or angle of inclination to the cathode.
  • a velocity-modulated electron beam tube comprising a cavity resonator provided with apertures for passage of an electron :beam therethrough, means adjacent said resonator for projecting therethrough an electron beam a part thereof adapted to pass through the antinode of standing waves developed in said resonator and an outer part thereof through an adjacent portion of the waves, beam control means to control the beam between said resonator and said projecting means for cutting-off the outer part of said beam, said beam control means being positioned along the beam path and having progressively greater control over said beam towards said outer part, and means connected to said beam control means for applying thereto a potential varying inversely with the length of said waves whereby the size of said beam is decreased with shorter waves.
  • a velocity-modulated electron beam tube comprising a cavity resonator provided with apertures for passage of an electron beam therethrough, means adjacent said resonator for projecting therethrough an electron beam its center adapted to pass through the antinode of standing Waves developed in said resonator and its outer parts through adjacent portions of the standing waves, and an electron-retarding electrode thereto.
  • said beam control means comprises a retarding electrode of flat metal provided with a slot in the beam path and transversely to the direction thereof, the opposite sides of said slot being progressively closer together adjacent the outer part of the beam path.
  • said beam control means comprises a retarding electrode provided with a slot in the beam path, said electrode being inclined to the direction of the beam path with the portion adjacent the outer part of the beam path located closer to the beam projecting means.
  • a velocity-modulated electron-beam tube comprising an elongated cavity resonator provided with a wide fiat path extending diametrically therethrough, means mounted adjacent said resonator for projecting along said path a flat electron beam adapted to pass parallel to standing waves developed in the resonator and the center part thereof adapted to pass through the antinode of such waves, and an electron-retarding electrode mounted between said projecting means and said resonator and provided with an elongated slot aligned with said path for passage of the beam therethrough, said slot being narrower towards its ends whereby said electrode cuts off progressively increased end portions of said flat beam when progressively lower cut-off potentials are applied thereto.
  • the retarding electrode comprises a flat metal member provided with an opening through which the beam path passes, the margins of said opening being curved in a plane transverse to the beam path with the concave side toward the means for projecting.

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  • Microwave Tubes (AREA)
US511094A 1942-05-08 1943-11-20 Oscillation generator of the velocity modulation type Expired - Lifetime US2485661A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB6279/42A GB582171A (en) 1942-05-08 1942-05-08 Improvements in oscillation generators of the velocity modulation type

Publications (1)

Publication Number Publication Date
US2485661A true US2485661A (en) 1949-10-25

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US511094A Expired - Lifetime US2485661A (en) 1942-05-08 1943-11-20 Oscillation generator of the velocity modulation type

Country Status (6)

Country Link
US (1) US2485661A (xx)
BE (1) BE474452A (xx)
ES (1) ES177015A1 (xx)
FR (1) FR941877A (xx)
GB (1) GB582171A (xx)
NL (1) NL74578C (xx)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2657329A (en) * 1950-02-21 1953-10-27 Sperry Corp Traveling wave tube
US3076117A (en) * 1959-04-27 1963-01-29 Gen Electric Parametric energy converter
US3104342A (en) * 1953-02-27 1963-09-17 Int Standard Electric Corp Electron velocity modulation tubes

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2048227A (en) * 1930-03-19 1936-07-21 Rca Corp Vacuum tube
US2064469A (en) * 1933-10-23 1936-12-15 Rca Corp Device for and method of controlling high frequency currents
US2169396A (en) * 1936-05-08 1939-08-15 Bell Telephone Labor Inc Signal-translating apparatus
US2320860A (en) * 1939-12-22 1943-06-01 Int Standard Electric Corp Electron discharge apparatus
US2407706A (en) * 1942-05-30 1946-09-17 Rca Corp Electron discharge device
US2411535A (en) * 1940-08-02 1946-11-26 Standard Telephones Cables Ltd High-frequency electron discharge apparatus

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2048227A (en) * 1930-03-19 1936-07-21 Rca Corp Vacuum tube
US2064469A (en) * 1933-10-23 1936-12-15 Rca Corp Device for and method of controlling high frequency currents
US2169396A (en) * 1936-05-08 1939-08-15 Bell Telephone Labor Inc Signal-translating apparatus
US2320860A (en) * 1939-12-22 1943-06-01 Int Standard Electric Corp Electron discharge apparatus
US2411535A (en) * 1940-08-02 1946-11-26 Standard Telephones Cables Ltd High-frequency electron discharge apparatus
US2407706A (en) * 1942-05-30 1946-09-17 Rca Corp Electron discharge device

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2657329A (en) * 1950-02-21 1953-10-27 Sperry Corp Traveling wave tube
US3104342A (en) * 1953-02-27 1963-09-17 Int Standard Electric Corp Electron velocity modulation tubes
US3076117A (en) * 1959-04-27 1963-01-29 Gen Electric Parametric energy converter

Also Published As

Publication number Publication date
NL74578C (xx)
BE474452A (xx)
GB582171A (en) 1946-11-07
ES177015A1 (es) 1947-04-16
FR941877A (fr) 1949-01-24

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