US2944181A - Electron velocity modulation apparatus - Google Patents

Electron velocity modulation apparatus Download PDF

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Publication number
US2944181A
US2944181A US507960A US50796055A US2944181A US 2944181 A US2944181 A US 2944181A US 507960 A US507960 A US 507960A US 50796055 A US50796055 A US 50796055A US 2944181 A US2944181 A US 2944181A
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United States
Prior art keywords
helix
wave
slow
tube
electron
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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
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US507960A
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English (en)
Inventor
Rogers Douglas Cecil
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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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Priority claimed from GB152558A external-priority patent/GB869201A/en
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Publication of US2944181A publication Critical patent/US2944181A/en
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    • 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
    • H01J23/36—Coupling devices having distributed capacitance and inductance, structurally associated with the tube, for introducing or removing wave energy
    • H01J23/40—Coupling devices having distributed capacitance and inductance, structurally associated with the tube, for introducing or removing wave energy to or from the interaction circuit
    • H01J23/48—Coupling devices having distributed capacitance and inductance, structurally associated with the tube, for introducing or removing wave energy to or from the interaction circuit for linking interaction circuit with coaxial lines; Devices of the coupled helices type
    • H01J23/52—Coupling devices having distributed capacitance and inductance, structurally associated with the tube, for introducing or removing wave energy to or from the interaction circuit for linking interaction circuit with coaxial lines; Devices of the coupled helices type the coupled helices being disposed coaxially around one another
    • 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
    • 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
    • H01J23/08—Focusing arrangements, e.g. for concentrating stream of electrons, for preventing spreading of stream
    • H01J23/083—Electrostatic focusing arrangements
    • 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
    • H01J23/16—Circuit elements, having distributed capacitance and inductance, structurally associated with the tube and interacting with the discharge
    • H01J23/24—Slow-wave structures, e.g. delay systems
    • 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
    • H01J23/16—Circuit elements, having distributed capacitance and inductance, structurally associated with the tube and interacting with the discharge
    • H01J23/24—Slow-wave structures, e.g. delay systems
    • H01J23/26—Helical slow-wave structures; Adjustment therefor
    • 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
    • H01J23/16—Circuit elements, having distributed capacitance and inductance, structurally associated with the tube and interacting with the discharge
    • H01J23/24—Slow-wave structures, e.g. delay systems
    • H01J23/30—Damping arrangements associated with slow-wave structures, e.g. for suppression of unwanted oscillations
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J25/00—Transit-time tubes, e.g. klystrons, travelling-wave tubes, magnetrons
    • H01J25/34—Travelling-wave tubes; Tubes in which a travelling wave is simulated at spaced gaps
    • H01J25/36—Tubes in which an electron stream interacts with a wave travelling along a delay line or equivalent sequence of impedance elements, and without magnet system producing an H-field crossing the E-field
    • H01J25/40—Tubes in which an electron stream interacts with a wave travelling along a delay line or equivalent sequence of impedance elements, and without magnet system producing an H-field crossing the E-field the backward travelling wave being utilised

Definitions

  • the present invention relates to travelling wave tubes in which an electron beam interacts with one of the spatial harmonics of an electromagnetic wave guided along a slow-wave structure, such as a helix.
  • a spatial harmonic travelling wave tube amplifier has been described by S. Millman in Bell Laboratories Record for January 1951 at page 14 and a backward wave oscillator utilizing similar principles has been described in the August 1953 issue of the same journal by R. Kompfuer.
  • the slow wave structure has a periodic arrangement of gaps in which the electron beam is able to interact with the electromagnetic field only at these gaps.
  • the propagation velocity of the fundamental mode of oscillation of the electromagnetic waves guided by the structure is very much greater than that of the beam electrons, the latter having velocities such that the difference between their time of flight and the propagation of the wave between adjacent gaps is. approximately that of an integral multiple of the oscillation period of the said fundamental mode.
  • a structure having discrete periodic gaps is not the only type of slow-wave structure adaptable to spatial harmonic interaction with an electron beam.
  • Certain kinds of helices such as are used in conventional helixtype travelling wave tubes can also be used, as appears, for example, from the paper The Helix as a Backward Wave Circuit Structure, by D. A. Watkins and E. A. Ash, published in the Journal of Applied Physics for June 1954 at page 782.
  • a conducting tape coiled into a helix then, to an electron travelling close to the ribbon, parallel to the axis of the helix, the structure will appear very similar to the periodic structures discussed above, interaction occurring at the gaps between adjacent turns.
  • a spatial harmonic travelling wave tube which expression is hereafter used to identify tubes constructed for interaction between an electron beam and one of the spatial harmonics of an associated slow-wave structure
  • the slow-wave structure is terminated at either end so as to reduce, as much as possible, end reflections over the range of frequencies for which the tube is designed to operate.
  • the spatial harmonic travelling wave tube may operate over a range of voltages including that appropriate to the amplification, by interaction with the fundamental mode of propagation, as in the conventional travelling-wave tube, of much lower frequency waves.
  • the terminations of the slow-wave structure will usually be far from reflectionless at frequencies far below the Patented July 5, 1960 designed operating range so that oscillation at such a lower frequency may easily result.
  • a spatial harmonic travelling wave tube comprising a slow-wave structure, such as a helix, which generates an electromagnetic field both within and externally of the structure having, at the desired frequency of operation, an axial phase velocity much greater than the velocity of electrons of an electron beam flowing within the structure parallel to the axis thereof, the beam interacting with spatial harmonics of the said field, characterized in this, that wave attenuation means is positioned at a distance from the said structure such as not substantially to afiect the growth of waves of the desired spatial harmonic mode but to suppress the growth of waves of a fundamental mode of lower frequency having an axial phase velocity approximately the same as the velocity of the beam electrons.
  • British Patent No. 660,793 (G. C. Dewey-L. D. Smullin 2-7), which is concerned with placing attenuating material around the helix of a conventional kind of travelling wave amplifier so as to suppress oscillation due to the fast mode of the field set up by the helix.
  • the spacing of the attenuation means of the present invention and of the prior invention from the surface of the slow-wave structure differ by about 2:1 and their actions are quite distinct.
  • the oscillator uses a special type of travelling wave tube 1 which comprises an electron gun 2 mounted at one end of a glass envelope 3, a metal tape coiled into a helix 4-, and an electron collector electrode 5 at the other end of the envelope 1.
  • the tube is mounted on the axis of beam focussing coils 6 and 7 so as to project through a rectangular waveguide 8, the arrangement being similar to that of a conventional travelling wave tube except that there is no input waveguide and the output waveguide is situated adjacent the electron gun in the position usually occupied by the input waveguide of a travelling wave amplifier.
  • the waveguide 8 and the helix 4 are coupled by the conventional arrangements of a probe antenna 9 and waveguide choke members 10 and 111.
  • the helix is supported on rods 12 of insulating material and is terminated at the collector end of the tube by coating the support rods 12 near their ends with resistance material as indicated at 13 and also provide a lossy anchorage 14 for the end of the helix.
  • an electron travelling parallel to the axis of the helix and close to the surface of the metal tape will encounter electromagnetic field conditions similar to those existing in a periodically gapped slow-wave structure, and will interact with the field only at the gaps between adjacent turns of the helix. Near the axis the field contributions of different circumferential regions of the helix will cancel one another, so that, so far as spatial harmonic operation is concerned, there is no eifective field on the axis. For this reason an annular electron beam is used and the electron gun comprises an annular cathode 15. In the drawing the Ar will be 0.355 of that at the helix surface.
  • a cup-shaped focussing electrode 16 is shown also to have a cup-shaped focussing electrode 16, a centrally apertured first anode 17 and, a second anode 18, the latter being formed on the end of a tubular rearward extension 19 of the waveguide choke member 11.
  • the potential difference between adjacent turns of the helix is made as large as possible.
  • the length of the circumference of one turn is, therefore, made about half a wave length for the desired mid-bank frequency of operation.
  • the length of one turn of the helix 4 is made 5 cm. and the helix pitch is 5 mm.
  • the oscillation frequency is changed continuously over a band of frequencies extending from about 2000 inc./s. to about 4000 mc./s.
  • helix dimensions having been chosen for maximum space harmonic interaction with the electron beam, it transpires that the same helix dimensions and a beam voltage of 2500 are just those providing good performance for a fundamental mode travelling wave amplifier at- 900 mc./s. Due to the inevitable mismatch of. the helix terminations at this frequency, far below the desired operating range, there is a considerable danger of self oscillation at or about 900 -me'./s.
  • a film of resistive material indicated in the drawing by the shading at 20, is placed about the helix at a distance therefrom where it will attenuate the fundamental mode around 900 mc. /s. without appreciably affecting the spatial harmonic fields in the band 2000 to 4000' mc./s.
  • British Patent No. 660,793 In the bodiments of the invention of British Patent No. 660,793,
  • the resistive film required for that invention for the suppression of fast 900 mc./s. modes conducted by a helix of the same form as used in the embodiment of the present invention would have to be spaced a distance of some 1.2 cms. from the surface of the helix about twice the distance required for use in the present invention.
  • the present invention provides a very simple solution to the difficulty, which would, otherwise, entail complicated extra matching arrangements for the helix terminations.
  • the attenuation means takes the form of a resistive film placed on the envelope 3 of the oscillator tube, the dimensions of the latter being suitable for the purpose.
  • the attenuation means couldtake other forms.
  • the helix could he supported'inside the main envelope in a closely fitting glass tube, the exterior of which is coated with resistive material.
  • the approximate distance at which the attenuation A means should be spaced from the surface ofthe helix-can be determined as follows.
  • a backward wave oscillator tube comprising an evacuated envelope, an electron gun at one end.
  • a backward wave oscillator according. to claim 2 in which the said film of resistive material is positioned externally of said envelope, the value of Ar including as a function the effect of dielectric material between the filth and the helix. 7 v
  • a spacial harmonic travelling wave tube comprising an electron beam source, a slow wave structure which generates for a desired spacial frequency mode an electromagnetic field at the desired operating'frequencyof said tube, having a phase velocity much greater thanthe velocity of the electrons of said beam, and also develops another electrpmag'netic field at a fundamental frequency and termination means for producing a substantial irnpedance match at one end of said structure for waves of said desired frequency characterized by additional wave attenuating means spaced radially of said structure at distance Ar from the surface of the slow-wave structure that 'yAr lies in the range 2.0 to 5.0 at the desired frequencies of operation of the tube, wher 'y is equal to 21r/A a being the wavelength of the mid-band frequency of the desired band of operation to substantially suppress said fundamental frequency waves but not to substantially affect the growth of waves of the spacial harmonic mode.

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  • Microwave Tubes (AREA)
US507960A 1954-08-05 1955-05-12 Electron velocity modulation apparatus Expired - Lifetime US2944181A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB22767/54A GB766914A (en) 1954-08-05 1954-08-05 Improvements in or relating to electron velocity modulation apparatus
GB152558A GB869201A (en) 1958-01-16 1958-01-16 Improvements in or relating to travelling wave tubes

Publications (1)

Publication Number Publication Date
US2944181A true US2944181A (en) 1960-07-05

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Family Applications (2)

Application Number Title Priority Date Filing Date
US507960A Expired - Lifetime US2944181A (en) 1954-08-05 1955-05-12 Electron velocity modulation apparatus
US777638A Expired - Lifetime US3013177A (en) 1954-08-05 1958-12-02 Travelling wave tubes

Family Applications After (1)

Application Number Title Priority Date Filing Date
US777638A Expired - Lifetime US3013177A (en) 1954-08-05 1958-12-02 Travelling wave tubes

Country Status (6)

Country Link
US (2) US2944181A (US20080094685A1-20080424-C00004.png)
BE (1) BE540343A (US20080094685A1-20080424-C00004.png)
DE (1) DE1257982B (US20080094685A1-20080424-C00004.png)
FR (6) FR1133939A (US20080094685A1-20080424-C00004.png)
GB (1) GB766914A (US20080094685A1-20080424-C00004.png)
NL (3) NL197957C (US20080094685A1-20080424-C00004.png)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3510721A (en) * 1966-12-29 1970-05-05 Siemens Ag Staggered attenuator for traveling-wave tubes

Families Citing this family (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3136964A (en) * 1954-05-12 1964-06-09 High Voltage Engineering Corp Radio frequency coupler and attenuator
US3193720A (en) * 1961-06-23 1965-07-06 Frank E Vaccaro Traveling wave tube slow wave structure having bi-filar helices
US3697799A (en) * 1970-01-13 1972-10-10 Teledyne Inc Traveling-wave tube package with integral voltage regulation circuit for remote power supply
USRE28782E (en) * 1970-01-13 1976-04-20 Teledyne, Inc. Traveling-wave tube package with integral voltage regulation circuit for remote power supply
US3735188A (en) * 1972-07-03 1973-05-22 Litton Systems Inc Traveling wave tube with coax to helix impedance matching sections
EP0127693B1 (de) * 1983-06-03 1987-09-09 ANT Nachrichtentechnik GmbH Verfahren zur automatischen Regelung der Ausgangsleistung eines Verstärkers

Citations (12)

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US2610308A (en) * 1947-10-31 1952-09-09 Int Standard Electric Corp Hyperfrequency electron tube
GB699893A (en) * 1951-04-13 1953-11-18 Csf Improvements in or relating to ultra high frequency travelling wave oscillators
US2669674A (en) * 1948-09-09 1954-02-16 Hartford Nat Bank & Trust Co Traveling wave tube
US2702370A (en) * 1953-03-18 1955-02-15 Csf Pulse-modulated traveling wave tube with crossed electric and magnetic fields
US2784339A (en) * 1947-06-25 1957-03-05 Rca Corp Electron discharge devices of the growing wave type
US2807744A (en) * 1951-07-27 1957-09-24 Csf Travelling wave magnetron tubes
US2808534A (en) * 1954-10-18 1957-10-01 Hughes Aircraft Co Traveling wave tube
US2820170A (en) * 1952-12-30 1958-01-14 Bell Telephone Labor Inc Spatial harmonic traveling wave tube
USRE24460E (en) * 1958-04-15 Traveling wave amplifier tube
US2843789A (en) * 1952-04-08 1958-07-15 Int Standard Electric Corp Arrangement for magnetic beam concentration
US2871451A (en) * 1953-12-21 1959-01-27 Bell Telephone Labor Inc Modulated backward wave oscillator
US2900557A (en) * 1954-08-26 1959-08-18 Gen Electric Traveling wave directional attenuator

Family Cites Families (10)

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Publication number Priority date Publication date Assignee Title
US2843790A (en) * 1951-12-14 1958-07-15 Bell Telephone Labor Inc Traveling wave amplifier
US2758244A (en) * 1952-06-02 1956-08-07 Rca Corp Electron beam tubes
US2849651A (en) * 1952-08-23 1958-08-26 Bell Telephone Labor Inc Traveling wave tubes
US2767259A (en) * 1952-10-01 1956-10-16 Rca Corp Noise compensation in electron beam devices
US2905858A (en) * 1953-06-30 1959-09-22 Bell Telephone Labor Inc Impedance matching by means of coupled helices
US2894168A (en) * 1953-11-20 1959-07-07 Itt Directional power dividers
DE1071851B (US20080094685A1-20080424-C00004.png) * 1954-11-29
US2814779A (en) * 1954-12-14 1957-11-26 Bell Telephone Labor Inc Microwave detector
US2847608A (en) * 1956-05-02 1958-08-12 Rca Corp Supporting device for helix in traveling wave tubes
US2862137A (en) * 1957-01-18 1958-11-25 Sperry Rand Corp Travelling wave tube

Patent Citations (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
USRE24460E (en) * 1958-04-15 Traveling wave amplifier tube
US2784339A (en) * 1947-06-25 1957-03-05 Rca Corp Electron discharge devices of the growing wave type
US2610308A (en) * 1947-10-31 1952-09-09 Int Standard Electric Corp Hyperfrequency electron tube
US2669674A (en) * 1948-09-09 1954-02-16 Hartford Nat Bank & Trust Co Traveling wave tube
GB699893A (en) * 1951-04-13 1953-11-18 Csf Improvements in or relating to ultra high frequency travelling wave oscillators
US2807744A (en) * 1951-07-27 1957-09-24 Csf Travelling wave magnetron tubes
US2843789A (en) * 1952-04-08 1958-07-15 Int Standard Electric Corp Arrangement for magnetic beam concentration
US2857547A (en) * 1952-04-08 1958-10-21 Int Standard Electric Corp Traveling wave tube
US2820170A (en) * 1952-12-30 1958-01-14 Bell Telephone Labor Inc Spatial harmonic traveling wave tube
US2702370A (en) * 1953-03-18 1955-02-15 Csf Pulse-modulated traveling wave tube with crossed electric and magnetic fields
US2871451A (en) * 1953-12-21 1959-01-27 Bell Telephone Labor Inc Modulated backward wave oscillator
US2900557A (en) * 1954-08-26 1959-08-18 Gen Electric Traveling wave directional attenuator
US2808534A (en) * 1954-10-18 1957-10-01 Hughes Aircraft Co Traveling wave tube

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3510721A (en) * 1966-12-29 1970-05-05 Siemens Ag Staggered attenuator for traveling-wave tubes

Also Published As

Publication number Publication date
NL105096C (US20080094685A1-20080424-C00004.png)
FR75010E (US20080094685A1-20080424-C00004.png) 1961-07-07
DE1257982B (de) 1968-01-04
FR1133939A (fr) 1957-04-03
NL235132A (US20080094685A1-20080424-C00004.png)
GB766914A (en) 1957-01-30
US3013177A (en) 1961-12-12
FR69028E (fr) 1958-08-27
BE540343A (US20080094685A1-20080424-C00004.png)
FR74801E (fr) 1961-03-03
FR75008E (US20080094685A1-20080424-C00004.png) 1961-07-07
NL197957C (US20080094685A1-20080424-C00004.png)
FR75009E (US20080094685A1-20080424-C00004.png) 1961-07-07

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