US3099766A - High capacity travelling wave tube for amplifying ultra high frequencies - Google Patents

High capacity travelling wave tube for amplifying ultra high frequencies Download PDF

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Publication number
US3099766A
US3099766A US148656A US14865661A US3099766A US 3099766 A US3099766 A US 3099766A US 148656 A US148656 A US 148656A US 14865661 A US14865661 A US 14865661A US 3099766 A US3099766 A US 3099766A
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Prior art keywords
delay line
electron beam
outer electrode
travelling wave
wave tube
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Expired - Lifetime
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US148656A
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English (en)
Inventor
Veith Werner
Meyerer Paul
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Siemens and Halske AG
Siemens Corp
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Siemens Corp
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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
    • H01J23/02—Electrodes; Magnetic control means; Screens
    • H01J23/09—Electric systems for directing or deflecting the discharge along a desired path, e.g. E-type

Definitions

  • This invention is concerned with a high capacity travelling wave tube, especially for the amplification of ultra high frequencies, employing purely electrostatic focusing of the electron beam, wherein the electron beam which is guided about the tube axis along a spiral path interacts with an electromagnetic Wave which is propagated along this spiral path.
  • travelling wave tube wherein the electrons are propagated upon helical paths along a helical delay line surrounding a preferably cylindrical cathode.
  • the corresponding tube is constructed in the manner of a magnetic field tube. Accordingly, for guiding or focusing the electron beam, there is required a magnetic field cooperating with additional electric fields.
  • travelling wave tube with purely electrostatic focusing in which the electron beam is upon an orbital path guided through the radial field of a cylinder condenser, one electrode of which is constructed as a delay line, so that an electromagnetic wave can azimuthally spread upon such electrode.
  • the delay effected by this line is in accordance with the supposition customary for travelling wave tubes so selected that the phase angle velocity of the electromagnetic Wave is approximately equal to the angular velocity of the electrons.
  • the orbital path of the electron beam is stabilized by the equilibrium obtaining between the force, acting due to the electrostatic field of the cylinder condenser, and the centrifugal force of the electrons.
  • the considerable advantage of this known travelling wave tube resides in that no magnetic field is required for the guidance of the electron beam. However, the power of this tube is relatively low due to the limited length of the orbital path.
  • the object of the invention is to provide a high capacity travelling wave tube with purely electrostatic focusing.
  • the advantage of the travelling wave tube according to the invention resides in that the high frequency energy is despite the absence of a magnetic field, similarly as in a magnetron, not derived from the kinetic energy of the electrons but from the potential energy of the electrostatic field.
  • An electron moving in the space between the outer electrode and the inner electrode would be subjected to braking forces upon giving off kinetic energy for conversion into high frequency energy. Since the electron loses thereby centrifugal force, it will reach a path nearer to the inner electrode, which extends upon a potential plane of a higher potential than that of the original path.
  • the electron accordingly retains the same angular velocity, so that the synchronism is preserved which exists between the electrons of the electron beam and an elec tromagnetic wave propagated along the delay line.
  • the electrons thereby move ever closer to the inner electrode, whereby the coupling between the electron beam and the high frequency field of the delay line is further improved.
  • the outer electrode In order to avoid, in a travelling wave tube according to the invention, undue disturbance of the high frequency properties of the delay line, it is advantageous to construct the outer electrode so that it comes in the region of the webs between which extends the high frequency field, closer to the inner electrode than in the range of the interaction areas between the webs. Such construction of the outer electrode also has the advantage that the electron beam is guided particularly close to the inner electrode in the regions of the interaction areas.
  • the efficiency of a travelling wave tube according to the invention can be increased, based upon an interaction mechanism which is similar to that of a magnetron, by constructing the collector for the electron beam of electrically mutually separated parts, and by connecting to the individual parts a direct potential of such magnitude that the respective impact energy of the electrons becomes as low as possible.
  • the par-ts of the collector which are subjected to the impact of electrons extending along a lower potential plane are for this purpose placed on a direct po tential which is correspondingly lower than that connected to the parts which are subjected to the impact of electrons extending along higher potential planes.
  • FIG. 1 represents a cross-sectional view of a cylinder condenser
  • FIG. 2 shows the amplifier part of a travelling wave tube formed by such a cylinder condenser, wherein the inner electrode is formed by webs of a delay line structure;
  • FIG. 3 indicates a structure having a polygonal outer electrode
  • FIG. 4 shows an outer electrode of another configuration
  • FIG. 5 illustrates a portion of an example of an embodiment of a travelling .wave tube according to the invention.
  • FIG. 6 shows in sectional view the collector end of a travelling wave tube according to the invention, having a particularly advantageous collector for the electron beam.
  • FIG. 1 showing in cross-sectional representation a cylinder condenser
  • numeral 1 indicates the outer electrode and numeral 2 the inner electrode.
  • the amplifier part of a travelling wave tube according to the invention forms approximately such a cylinder condenser, whereby the inner electrode 2 is however formed by parts of a delay line structure represented as webs or rods 3 (-FIG. 2) between which extends the high frequency field of the line.
  • the remaining parts of the de.ay line structure, which are to be enveloped by the outer electrode 1, have been omitted from the drawing.
  • To the rods 3 is, as compared with the outer electrode 1, connected a high direct potential, resulting in an electrostatic field indicated in FIG. 3 by the arrows 4.
  • the path '5 is not circular as in the case of an ideal cylinder condenser, but angular.
  • the angular form has, as compared with the circular form, the advantage that the electrons come closer to the interaction paths lying bet-ween the rods 3 than they come to the rods.
  • the coupling between the electron beam and the high frequency field which is already relatively good owing to the greater density interiorly of the electron beam, is thereby improved.
  • the angular path of the electrons can be emphasized by appropriate configuration of the outer electrode, such that the outer electrode comes in the region of the rods or webs 3 closer to the inner electrode than in the regions of the interaction areas extending between the rods 3. Such configuration also avoids detrimentally affecting the delay line by the outer electrode.
  • a suitable embodiment of a polygonal outer electrode is shown in FIG. 3 and another embodiment thereof is shown in FIG. 4.
  • Such an outer electrode can be produced in particularly simple manner by drilling holes in an originally circular structure at points lying opposite the interaction areas.
  • the bars 3 are angularly formed in the direction of the outer electrode so as to obtain in the regions of the bars a stronger concentration of the electrostatic field.
  • FIG. 5 shows a partial view of m embodiment of a travelling wave tube according to the invention.
  • the hollow delay line or wave guide structure 6, the inner wall of which is broken in meandering manner, is wound spirally.
  • the tongue or finger-like wall parts 7 remaining between the meandering open portions correspond to the rods or bars 3 in FIGS. 2 to 4.
  • interiorly of the structure 6 is disposed 21 Likewise spirally wound metal member 8 which is electrically separated from the structure 6.
  • the metal member 8 may be held by means of a member 9 which is sealed by fusing in the outer wall of the structure '6 and which shall also serve as a terminal.
  • the metal member 8 is placed on cathode potential referred to a voltage of 0 volt or less, and the structure '6 disposed opposite thereto is placed on a high direct voltage.
  • the electron beam 10 is thereby in stable manner guided upon l its path between the metal structure 8 and the webs 7.
  • the arrangement of the main mass of the delay line on the outside necessarily results in loading of the outer electrode, such loading in turn resulting in a shifting of the conduction character toward longer waves. Accordingly, the geometrical dimensions of the delay line structure can thereby be held smaller than in the case of a line without loading, whereby the geometrical dimensioning of the tube is further facilitated.
  • a delay line according to FIG. 5 is in simple manner constructed from a hollow cylindrical copper block. Such block is machined so that there remains interiorly of the wall a fiat band-shaped spindle corresponding to the horizontal parts of the delay line structure 6. Into the free ledge of the spindle are milled an odd number of grooves which are symmetrically distributed over the circumference thereof. Into these grooves are soldered webs at the center thereof, after inserting the outer elctrode into the line. The length of the webs exceeds the pitch of the spindle, so that the ends of the webs interlace interdigitally in the direction of the spindle.
  • a delay line structure according to FIG. 5 has a rearwardly running fundamental wave.
  • the tube For amplifier operation, the tube must therefore be dimensioned so that the electron beam is in synchronism with the first forwardly running partial wave. This results in the advantage that the dispersion of the forwardly running first partial wave is in the illustrated delay line structure very slight.
  • FIG. 6 shows a sectional view of the collector end of a travelling wave tube provided with a particularly advantageous collector. Owing to the interaction with the high frequency field of the delay line, the electrons of the electron beam move at the end of the tube along paths of different radii. The electrons with the greatest energy loss follow the smallest radius, therefore moving closely interiorly at the inner wall of the delay line structure 6.
  • the electrons with the least energy loss move outside at the outer electrode ll.
  • the collector is therefore subdivided into three annular metal members 13, 14, 15. These metal members are electrically mutually separated and connected to different potentials.
  • the rnetal member 13 with the smallest diameter receives the highest positive direct potential and the metal member 15 with the greatest diameter receives the lowest positive direct potential. This arrangement makes it possible to keep the respective impact energy of the electrons low.
  • the invention is not inherently limited to the illustrated and described embodiments. It is in particular possible to use in place of the delay line according to FIG. 5 another suitable periodic structure.
  • a high capacity travelling wave tube especially for amplifying ultra high frequencies, with purely electrostatic focusing of the electron beam, wherein the electron beam which is guided about the tube axis upon a helical path, enters into reciprocal action with an electromagnetic wave propagated along such path, said wave spreading with azimuthal delay upon a helically extending hollow delay line structure provided with periodic breaks formed at least in the wall parts thereof facing the tube axis, in the space between a metallic structure, forming an outer electrode, the latter and the delay line extending helically in mutually parallel relation about the tube axis with the outer electrode electrically separated from the delay line structure and wall parts of the delay line structure, forming an inner electrode, said delay line forming a part of a hollow cylindrical metal structure which, jointly with the delay line structure, surrounds the outer electrode.
  • a travelling wave tube according to claim 2 wherein said webs are angularly shaped at the parts thereof which face said outer electrode.
  • a travelling wave tube comprises a generally rectangular shaped wave guide, the wall of said Wave guide facing the tube axis being broken meander-like, said outer conductor being held in said wave guide in insulated relation with respect to the delay line structure.
  • a travelling wave tube having a collector for the electron beam comprising a plurality of annular electrically separated metallic members of different diameter, the respective members of smaller diameter being placed on a higher positive direct potential than the respective neighboring metal member of smaller diameter.
  • a travelling wave tube according to claim 8 wherein said collector comprises three successively stage-like positioned annular metal members.

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US148656A 1960-11-02 1961-10-30 High capacity travelling wave tube for amplifying ultra high frequencies Expired - Lifetime US3099766A (en)

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NL (1) NL270229A (en, 2012)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3277332A (en) * 1962-04-25 1966-10-04 Siemens Ag Electrostatically focused high power traveling wave tube with spiral electron beam path

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2325865A (en) * 1940-08-17 1943-08-03 Int Standard Electric Corp Electrode structure for velocity modulation tubes
FR1006335A (fr) * 1947-12-20 1952-04-22 Tube électronique pour hyperfréquence
US2730678A (en) * 1951-12-29 1956-01-10 Csf Improvements in interdigital delay lines
US2844797A (en) * 1953-10-23 1958-07-22 Raytheon Mfg Co Traveling wave electron discharge devices
US2900558A (en) * 1957-07-18 1959-08-18 Hewlett Packard Co Beam-type tube
US3058025A (en) * 1958-01-01 1962-10-09 M O Valve Co Ltd Electrostatic focussing devices

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2325865A (en) * 1940-08-17 1943-08-03 Int Standard Electric Corp Electrode structure for velocity modulation tubes
FR1006335A (fr) * 1947-12-20 1952-04-22 Tube électronique pour hyperfréquence
US2730678A (en) * 1951-12-29 1956-01-10 Csf Improvements in interdigital delay lines
US2844797A (en) * 1953-10-23 1958-07-22 Raytheon Mfg Co Traveling wave electron discharge devices
US2900558A (en) * 1957-07-18 1959-08-18 Hewlett Packard Co Beam-type tube
US3058025A (en) * 1958-01-01 1962-10-09 M O Valve Co Ltd Electrostatic focussing devices

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3277332A (en) * 1962-04-25 1966-10-04 Siemens Ag Electrostatically focused high power traveling wave tube with spiral electron beam path

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