US2939992A - Traveling wave electron discharge devices - Google Patents

Traveling wave electron discharge devices Download PDF

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Publication number
US2939992A
US2939992A US472925A US47292554A US2939992A US 2939992 A US2939992 A US 2939992A US 472925 A US472925 A US 472925A US 47292554 A US47292554 A US 47292554A US 2939992 A US2939992 A US 2939992A
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United States
Prior art keywords
impedance
conductor
line
point
strip
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Expired - Lifetime
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US472925A
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English (en)
Inventor
Albert G Peifer
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TDK Micronas GmbH
International Telephone and Telegraph Corp
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Deutsche ITT Industries GmbH
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Priority to BE543286D priority Critical patent/BE543286A/xx
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Priority to US472925A priority patent/US2939992A/en
Priority to GB34568/55A priority patent/GB788625A/en
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Publication of US2939992A publication Critical patent/US2939992A/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
    • H01J23/50—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 interaction circuit being a helix or derived from a helix

Definitions

  • This invention relates to traveling wave electron discharge devices and more particularly to transition arrangements for matching a low impedance waveguide to the relatively high impedance waveguiding structure usually employed in such devices.
  • transition arrangements which provide for impedance matching between the end of the high impedance helical transmission line and the relatively low impedance radio frequency terminal connections of a traveling wave electron discharge device or tube.
  • the transition arrangements are disposed transversely of the axis of the helix and made in such form as to require but a small fraction of an inch of space measured in an axial direction.
  • the impedance matching arrangements of the first two copending applications include parallel transmission line sections, the lengths of which are frequency dependent while the latter copending application includes a series transmission line section, the radial dimension of which is frequency dependent.
  • the traveling wave tubes employing these impedance matching arrangements will have a diameter dependent upon the frequency at which the tube is operating and in certain instances this diameter may be quite large.
  • Another object is to provide transition sections for precise matching of a low impedance radio frequency coaxial terminal connection to a high impedance helical line.
  • One of the features of this invention is the structural arrangement of the transition section, that is, the special shaping of certain of the conductors thereof so as to provide gradual transition from the size of the outer conductor of the coaxial terminal connection to the smaller conductor size of a helical line and for cooperation in the impedance matching function. This is accomplished by tapering the width of the transition section.
  • Another feature of this invention is the provision of a specially designed strip conductor in conjunction with a cylindrical conductor for transmission of radio fre- .of an embodiment of the present invention.
  • Still another feature of this invention is .the provision of a spiral strip conductor in conjunction with a cylindrical conducting surface wherein the strip conductor and the cylindrical conducting surface are coupled together at one point to establish a radio frequency voltage null, said coupling together being capacitive in nature and the point of coupling being variable along a given are of the cylindrical conducting surface to enable the selection of a predetermined frequency of operation Within a given range of operating frequencies for a traveling wave tube.
  • Fig. 1 is a fragmentary view in longitudinal section of a traveling wave electron tube incorporated in transition sections at the ends of a helical line in accordance with the principles of this invention
  • Fig. 2 is a cross-sectional view of the transition section of this invention taken along line 2-2 of Fig. 1;
  • Fig. 3 is a cross-sectional view of an alternative embodiment of the transition section of this invention.
  • the tube generally comprises an electron gun unit 1 for producing a beam of electrons for flow axially of the tube to a collector 2.
  • the electron gun unit is either spaced from or made contiguous to an alignment or partition plate 3 which is positioned crosswise vacuum envelope 4 against abutment 5 on the inner surface thereof.
  • Envelope 4 preferably is composed of a non-magnetic metallic material in the embodiment presently being discussed, but it is to be understood that the vacuum envelope may be composed of dielectric'material which has disposed concentrically therewith a non-magnetic metallic cylinder as disclosed in the cross-sectional view of Fig. 3.
  • a permanent magnet or magnetic coil-7 which serves to produce a magnetic field axially of the envelope 4.
  • a second alignment or partition plate 8 Interposed between these two plates 3'and 8 is a radio frequency propagating structure 9 in the form of a helical trans-.
  • the line being supported by dielectric rods 10 or by a dielectric tube, whichever is desired. Any suitable dielectric, such as glass or quartz may be employed.
  • the rods or tubing are supported on the plates 3 and 8 in openings 11 and 12.
  • the helical line 9 is connected between the input and output radio frequency terminal connections 13 and 14 by means of transition arrangements or sections 15 and 16, respectively.
  • the transition section 15 comprises a transmission line arrangement of the line-above-ground type which includes the envelope 4 as one of the. couductors and a strip conductor 17 as the other conductor wherein conductor 4 provides a reference or ground plane separated from the strip conductor 17 by a suitable dielecshown herein to be vacuum but may comwise coupled to the helical line 9.
  • the strip conductor equal 'approximately to a quarter wavelength long or an odd multiple. thereof overthe operating frequency range ofthe traveling'wa've tube, the 'secti0n 15 becomes resonant. and thereby establishes a standing wave with a voltage null'at theshort. 19 and a voltage maximum at theend coupled to the. helical line 9.
  • Theouter conductor 20 of the input radio frequency terminal con nectionli isconnectedto'envelope 4 and the inner confacsaoaa- 4 tween the strip conductor-17 and the cylindrical conducting surface of envelope 4.
  • the tapering of the width of strip 17 enables a transition between the size of the center conductor 21of connection 13 and the size of the conductor forming helical line 9 and also cooperates in the desired impedance match.
  • This tapering of the width of strip, 17 as indicated at 25 also aids in obtaining a wide bandwidthsin the transition section 15, the bandwidth of which should be as large as the bandwidth of the remaining portions of 'thejtraveling wave tube.
  • connection between inner conductor 21 and strip 17 may be p'rovided by a conductor 22 brazed or otherwise bonded .to conductor' 17 and projecting through an aperture'in envelope '4' which makes electrical contact with inner conductor 2'11by means of socket 23.
  • the aperture through which conductor .22 passes through envelope 4 is sealed for vacuum purposes by the dielectric seal '24.
  • the connection to strip conductor 17 isrlocated at a point between the voltage null (minimum impedance), and vthe'voltage maximum (maximum impedance) points'so as re provide. a proper impedance matchbetween the impedance helical line 9 and the low impedance coaxial'connection 13.
  • the strip is tapered as indicated
  • the transition coupling 15 inFigs. 1 and 2 provides for the'propagation of radio frequencye'nergy from .the
  • the transition section 16 rangement-to eliminate any radiation which: may occur from the transmission sectionand whichmight interfere in the desired operation of the traveling wave tube.
  • the radiation problem when employing aitransiti'on arrangement of the type herein described is substantially elimi nated by dimensioning the envelope 4 to have a diameter of such a value that this envelope or outer cylinder functions as a waveguidebeyond cutoff for the operating frequency of the device. lf this is done, radiation in either direction from the'transition'arrangement is eliminated.
  • this cylinder as the envelope 4 as hereinabove proposed, the. overall diameter of the traveling wave tube maybe substantially decreased.
  • the coaxial vacuum seal 24 of Figl the coaxial vacuum seal 24 of Figl.
  • the envelmac 4 thereof could be ceramic rather than metallic.
  • the strip conductor 17 spaced. a'small fraction of, a
  • the cylindrical conducting sur: face of the envelope 4s provides for the propagation of a mode approximating the TEM mode.
  • the strip17 is preferably of a width' suificient to provide satisfactory coupling to the coaxial transmission line, the portion disposed hetween'this coupling and the helicalline being 1 fco'operate' in' the impedance transition between helical line 9 and connection 13.
  • the dimension h for the strip 17 over jthepcylindrical conducting surface of envelope 4 may 'be obtained fromithe expression Thus, in Fig.
  • envelope 4a be formed from a suitable dielectricmaterial, such as quartz or glass, which has disposed .thereabout in a concentric relation conductive cylinder 6 to function as the ground plane of the concentric-like strip-above-ground type transmission [line for utilization in the transition arrangement of this electromagnetic waves from the coaxial connection 13 in V where h is the spacingof the strip from the cylindrical surface, d the width of the strip 17 and s isthe dielectric constant of the dielectric material disposed between the strip and" the cylindrical surface.
  • h is the spacingof the strip from the cylindrical surface
  • d the width of the strip 17 and s isthe dielectric constant of the dielectric material disposed between the strip and" the cylindrical surface.
  • Strip conductor 17a is coupled to conducting cylinder 6 capacitively to .provide a resonant transition section as disclosed in connection with Figs. 1 and 2.
  • Portion 26 of strip conductor 17a 'eifectively is one plate of a capacitor
  • sliding element 27 forms the other plate of a capacitor with the dielectric material of envelope 4a functioning as the dielectric material disposed therebetween.
  • This structurejarrangernent provides a capacijtiveshort for radio frequency wavesbetweencylinder 6 and strip"17a.
  • Sliding element 27 is in slidable contact witha portion of cylinder 6 over asmaller arc thereof. Element 27 may be moved by handle 28 in' slot 29 to change the location of the short .or coupling between strip 17a and cylinder 6.
  • the slot 29 must be covered at all times and in all positions of element 27 by element 27 to prevent undesired radiation from the traveling wave tube'through slot 29.
  • Thisradiation consideration therefore, restricts the number of frequencies which may be selected from a given rangeofsoperating frequencies.
  • a transition section coupling said low impedance line to said propagating structure comprising a first conductor substantially concentric with the longitudinal axis of said propagating structure, a second conductor spaced radially from said first conductor having a substantially spiral-like configuration about said longitudinal axis, said first and second conductors forming a transmission line spaced radially from and disposed about an end of said propagating structure, means coupling said first and second conductors together at one point to establish a radio frequency voltage null, the length of said transmission line from said voltage null measured circumferentially therealong providing a resonant section resonant at approximately the operating frequency of said device, said transmission line having a high radio frequency voltage portion disposed adjacent said propagating structure, means connecting said high voltage portion to said propagating structure, and means to couple said low impedance line to said first and second conductors at
  • a transition section coupling said low impedance line to said propagating structure comprising a first conductor substantially concentric with the longitudinal axis or" said propagating structure, a second conductor spaced radially from said first conductor having a substantially spiral-like configuration about said longitudinal axis, said first and second conductors forming a transmission line spaced radially from and disposed about an end of said propagating structure, means coupling said first and second conductors together at one point to establish a radio frequency voltage null, the length of said transmission line from said voltage null measured circumferentially therealong providing a resonant section resonant at approximately the operating frequency of said devi e, said transmission line having a high radio frequency voltage portion disposed adjacent said propagating structure, means connecting said high voltage portion to said propagating structure, means to couple said low impedance line to said first and second conductor
  • a transition section coupling said low impedance line to said propagating structure comprising a first conductor substantially concentric with the longitudinal axis of said propagating structure, a second conductor spaced radially from said first conductor having a substantially spiral-like configuration about said longitudinal axis, said first and second conductors forming a transmission line spaced radially from and disposed about one end of said ro a atin structure, ca acitive means coupling said first and second conductors together at one point to establish a radio frequency voltage null, the
  • said transmission line having a high ratio frequency voltage portion disposed adjacent said propagating structure, means connecting said high voltage portion to said propagating structure, and means to couple said low impedance line to said first and second conductors at a point between said voltage null and said high voltage portion to match the impedance of said low impedance line.
  • a transition section coupling said low impedance line to said helical structure comprising a cylindrical conducting surface substantially concentric with the longitudinal axis of said helical structure, a strip conductor spaced radially from said surface having a substantially spiral-like configuration about said longitudinal axis, said surface and said strip forming a transmission line spaced radially from and disposed about an end of said helical structure, means coupling said surface and said strip together at one point to establish a radio frequency voltage null, the length of said transmission line from said voltage null measured circumferentially therealong providing a resonant section resonant at approximately the operating frequency of said device, said transmission line providing a voltage maximum point at a distance of approximately a quarter Wavelength of said operating frequency from said null point, means coupling said low impedance line to said surface and said strip at a point between said null and
  • a transition coupler for use between a low impedance transmission line and a high impedance transmission line comprising a first conductor substantially concentric with a given axis, a second conductor spaced radially from said first conductor having a substantially spiral-like configuration about said given axis, said first and second conductors forming a transmission line, means coupling said first and second conductors together at one point to establish an impedance minimum, the length of said transmission line from said impedance minimum measured circumferent-ially therealong providing a resonant section resonant at a given frequency, said transmission line having an impedance maximum point at a distance approximately one quarter wavelength of said given frequency from said impedance minimum point, means coupling said low impedance line to said first and second conductors at a point between said minimum and maximum impedance points, and means to connect saidsecond conductor in the zone of said maximum impedance to said high impedance line.
  • a transition coupler for use between a low impedance transmission line and a high impedance transmission line comprising a first conductor substantially concentric with a given axis, a second conductor spaced radially from said first conductor having a substantially spirallike configuration about said given axis, said first and second conductors forming a transmission line, means coupling said first and second conductors together at one point to establish an impedance minimum point, the length of said transmission line from said impedance minimum point measured circumferentially therealong providing a resonant section resonant at a given frequency, said transmission line having an impedance maximum point at a distance of approximately one quarter wavelength of said given frequency from said minimum point, means coupling said low impedance line to said first and second conductors at a point between said impedance minimum and impedance maximum points -'-to matchthe in'ipedance of said lowi impedance line, means connecting said second-conductor in the regicnrof said f impedance maximum point to said
  • Atransition' coupler for use between a' low'impedance transmission line and a high impedance transmission line comprising a first conductor substantially concentric "with a given axis, a second conductor spacedradially from s'aid first'conductor having asubstantially spiral-like configuration about said' given axis; said first and second conductors forming a transmission 1ine,'rnean's coupling said firstand second conductors together at a point to,
  • lOV-A traveling wave electron discharge device comprising a metallic envelope, means'to project an electron beam along a path axially of said envelope, a radio frequency wave propagating structure of relatively high characteristic impedance disposed coaxially of said path, a radio frequency wave input terminal connection of relatively low characteristic impedance, a radio frequency wave output terminal connection of relatively low characteristic impedance, artransition sectioncoupling said input connection to the end of said propagating structure adjacent said means to project for the propagation of radio frequency wave therealong for interaction with the electrons of said beam, and a transition section coupling said output connection to the other end of said propagating-structure for removal of the interacted radio frequency waveethereirom, each of said transition sections including said envelope and a conductor spaced radially from said envelope having a substantially'spiral-like config uration'about the axis of said envelope, said envelope 7 and said conductor forming a transmission line spaced radially from and disposed about the respcctive end of -said propagating structure, means coupling
  • said transmission line having an impedance maximum point at a distance of'approximately one quarter wavelength of said given-frequency from said impedance min imum point, means. coupling said low impedance line to said'surface and said strip at a point between said'impedance minimum and impedance maximum points to match the impedance of said low impedance line, and means connecting said strip in the region of said maximum impedance point to said high impedance line.
  • a transition coupler for'irnpedance matching be tween 2.
  • a device 1 1'.
  • the diam- V eter of said envelope is such as to establish said envelope as a waveguide beyond cutoff for the operating frequency of said device and the inner surface of said envelope defines a cylindrical conductive surface and said conductor includes a strip of conducting material separated from said cylindrical conducting surface by a dielectric medium V 2.
  • said strip includes a strip of conducting material separated from said cylindrical conducting surface by a dielectric medium V 2.
  • a traveling wave electron dischargeedevice comprising a vacuum envelope of dielectric material, means to project an electron beam along a path axially'of said envelope, a helical radio'frequency wave propagating structure of relatively high characteristic impedance disposed coaxially of said path, a radio frequency wave input terminal connection of relatively low characteristic impedance, a radio frequency Wave output terminal connection of relatively low characteristic impedance, a transition section coupling said input connection to the end of said helical structure adjacent said means to project for launching radio frequency waves on said helical structure for interaction with the electrons of said beam, a transition section coupling said output connec- -tion to the other end of said helical structure for removal of the interacted radio frequency wave therefrom, and a metallic sleeve disposed in concentric spacedrelation to said envelope, each of said transition sections including said sleeve and a conductor spaced radially from said sleeve having a' substantially spiral-like configuration about the axis of said envelope, said slee

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US472925A 1954-12-03 1954-12-03 Traveling wave electron discharge devices Expired - Lifetime US2939992A (en)

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Application Number Priority Date Filing Date Title
BE543286D BE543286A (enrdf_load_html_response) 1954-12-03
US472925A US2939992A (en) 1954-12-03 1954-12-03 Traveling wave electron discharge devices
GB34568/55A GB788625A (en) 1954-12-03 1955-12-02 Travelling wave electron discharge devices

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3185884A (en) * 1962-08-01 1965-05-25 Sfd Lab Inc Microwave coupling apparatus for slow wave circuits and tubes using same
US3271615A (en) * 1961-08-23 1966-09-06 Westinghouse Electric Corp Traveling wave electron discharge device having means exerting a radial force upon the envelope
US20090127480A1 (en) * 2007-11-13 2009-05-21 Jenact Limited Methods and apparatus for generating ultraviolet light

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
USRE23647E (en) * 1947-06-25 1953-04-21 High-frequency electron discharge
US2712614A (en) * 1950-06-30 1955-07-05 Univ Leland Stanford Junior Travelling wave tubes
US2727179A (en) * 1954-04-29 1955-12-13 Sperry Rand Corp Travelling wave tube
US2774006A (en) * 1950-10-14 1956-12-11 Univ Leland Stanford Junior Travelling wave tube apparatus

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
USRE23647E (en) * 1947-06-25 1953-04-21 High-frequency electron discharge
US2712614A (en) * 1950-06-30 1955-07-05 Univ Leland Stanford Junior Travelling wave tubes
US2774006A (en) * 1950-10-14 1956-12-11 Univ Leland Stanford Junior Travelling wave tube apparatus
US2727179A (en) * 1954-04-29 1955-12-13 Sperry Rand Corp Travelling wave tube

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3271615A (en) * 1961-08-23 1966-09-06 Westinghouse Electric Corp Traveling wave electron discharge device having means exerting a radial force upon the envelope
US3185884A (en) * 1962-08-01 1965-05-25 Sfd Lab Inc Microwave coupling apparatus for slow wave circuits and tubes using same
US20090127480A1 (en) * 2007-11-13 2009-05-21 Jenact Limited Methods and apparatus for generating ultraviolet light
US8026497B2 (en) * 2007-11-13 2011-09-27 Jenact Limited Methods and apparatus for generating ultraviolet light

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GB788625A (en) 1958-01-02

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