US3172005A - Beam convergence in velocitymodulating valve - Google Patents

Beam convergence in velocitymodulating valve Download PDF

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US3172005A
US3172005A US72902A US7290260A US3172005A US 3172005 A US3172005 A US 3172005A US 72902 A US72902 A US 72902A US 7290260 A US7290260 A US 7290260A US 3172005 A US3172005 A US 3172005A
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pole
electron beam
piece
aperture
pieces
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US72902A
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Bernardus Bastiaan Van Iperen
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US Philips Corp
North American Philips Co Inc
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US Philips Corp
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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
    • H01J25/10—Klystrons, i.e. tubes having two or more resonators, without reflection of the electron stream, and in which the stream is modulated mainly by velocity in the zone of the input resonator
    • H01J25/12—Klystrons, i.e. tubes having two or more resonators, without reflection of the electron stream, and in which the stream is modulated mainly by velocity in the zone of the input resonator with pencil-like electron stream in the axis of the resonators
    • 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

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  • This invention relates to velocity-modulating tubes in which an electron beam is converged electrostatically to a point inside one of two pole-pieces between which a magnetic field directed axially relative to the electron beam is present.
  • the magnetic field has a strength such that the electron beam upon reaching the second polepiece has a diameter substantially equal to its diameter at the first pole-piece. Since the diameter of the electron beam is determinative of how small the wavelength may be of the cavity resonator bringing about velocity-modulation in the electronic beam, the oscillations which can be produced or amplified by means of such a velocitymodulating tube have frequencies which are comparatively limited.
  • An object of the invention is to provide a velocitymodulating tube of the above-mentioned type which permits of obtaining higher frequencies.
  • the strength of the magnetic field is in connection with the velocity of the electron beam such that the electron beam reaches a minimum diameter at the second pole-piece, while inside or immediately after the pole-piece means are provided for bringing about velocity-modulation in the beam and/or extracting energy therefrom.
  • the beam after having passed through the first pole-piece, decreases still further in diameter, it may coact inside or after the second pole-piece with a cavity resonator of a considerably shorter wave-length than in the event that the diameter of the beam would have remained unchanged after the first pole-piece.
  • the invention can be applied in the simplest way to a velocity-modulating tube having only one cavity resonator, i.e. a reflex klystron, but since the decrease in the diameter of the electron beam is not permanent, but repeated periodically, it is alternatively possible to arrange the pole-pieces a little further remote from each other and to mount another cavity resonator between them, resulting in a klystron having two cavity resonators.
  • FIGURE 1 is a cross-sectional view of a reflex klystron according to the invention and FIGURE 2 shows a cross-section of a klystron having two cavity resonators.
  • FIGURE 1 shows pole-pieces 1 and 2 of a permanentmagnetic block 3.
  • a hollow cathode 4 emits with the aid of a focusing electrode 5 and a front side 6 of the pole-piece 1 an electron beam with contours 7 through an aperture 3 provided in pole-piece 1. The minimum diameter is reached approximately at the rear side of the pole-piece 1.
  • Several magnetic lines of force extending from the aperture 8 to the pole-piece 2 are indicated by 9. Due to the fact that the electrons travel at right angles to these lines of force, they are subject to a force along the periphery of the beam at right angles to the 3,172,005 Patented Mar. 2, 1965 direction of travelling, resulting in a circular movement being superimposed on the rectilinear movement.
  • the electrons encounter forces directed towards the axis and consider-ably decreasing the diameter of the beam.
  • the beam of small diameter passes, at 19, through the gap in a cavity resonator 11 which is made of copper and arranged within the pole-piece 2.
  • the electron beam slightly diverges and is reflected by a reflector electrode 12 to the aperture 10 and towards the pole-piece 1.
  • the vacuum closures at the two ends of the reflex klystron are not shown.
  • the cathode 4 has a negative potential of about 1000 volts and the reflector electrode 12 has a negative potential of 300 volts relative to the pole-pieces 1 and 2.
  • the voltage of the focusing electrode 5 differs but slightly from that of the cathode 4.
  • the diameter of a hollow cathode 4 is 0.8 mm.
  • the aperture 8 has a minimum diameter of 0.3 mm. and the aperture 10 in the cavity resonator 11 has a diameter of 0.1 mm.
  • the electron current from the cathode is 30 mamps.
  • the cavity resonator 11 has dimensions such that the oscillations produced by the reflex klystron have a wave-length of about 2.5 mms.
  • the spacing between the adjacent sides of the polepieces is 1.3 mm. and the magnetic field in the axis of the beam has a strength of about 3300 gauss.
  • FIGURE 2 differs from FIGURE 1 only insofar that between the two pole-pieces, which now have a spacing of 4 mms. between them, another cavity resonator 13 having an aperture 14 is provided at the area where the electron beam has a minimum diameter for thefirst time. The second minimum of the diameter falls again in the aperture 10 of the cavity resonator 11.
  • the cavity resonator 13 is supported by means of a copper block 15 which bears on the pole-piece 2.
  • the collector electrode for the electrons having passed the cavity resonator 11 is indicated by 16.
  • the wave-guides for the supply and discharge of the energy in the cavity resonators are not shown.
  • a velocity modulating tube comprising means to generate and project an electron beam along a given direction, first and second pole-piece members each having an aperture through which the electron beam passes, focussing means for converging the electron beam to a point within the aperture of one of said pole-pieces, said pole-pieces defining therebetween a magnetic field coaxial with the electron beam having a strength at which the electron beam has a minimum diameter at the second pole-piece member, and means in proximity to the second pole-piece member for selectively velocity modulating the electron beam and extracting energy therefrom.
  • a velocity modulating tube comprising means to generate and project an electron beam along a given direction, first and second pole-piece members each having an aperture through which the electron beam passes, focussing means for converging the electron beam to a point within the aperture of one of said pole-pieces, said polepieces being spaced apart and defining therebetween a magnetic field coaxial with the electron beam having a strength at which the electron beam has a minimum diameter between the pole-piece members, a first resonant cavity between the pole-pieces through which the beam passes and is velocity modulated, and a second cavity resonator in the proximity of the point at which the electron beam has a minimum diameter through which the beam passes and energy is extracted therefrom.
  • a velocity modulating tube comprising means to generate and project an electron beam along a given direction, first and second pole-piece members each having an aperture through which the electron beam passes, electrostatic focussing means for converging the electron beam to a point within the aperture of one of said polepieces, said pole-pieces defining therebetween a magnetic field coaxial with the electron beam having a strength at which the electron beam has a minimum diameter at the second pole-piece member, a cavity resonator in proximity to the point at which the beam has a minimum diameter and for velocity modulating and extracting energy from the beam, and a reflector electrode positioned after said second pole-piece for reflecting electrons in said beam passing through the aperture in the second pole-piece member.
  • a velocity modulating tube comprising means to generate and project an electron beam along a given direction, first and second pole-piece members each having an aperture through which the electron beam passes, electrostatic focussing means for converging the electron beam to a point within the aperture of one of said polepieces, said pole-pieces being spaced apart and defining therebetween a magnetic field coaxial with the electron beam having a strength at which the electron beam has a minimum diameter between the pole-pieces and at the second pole-piece member, a cavity resonator in the proximity of the point between the pole-pieces at which the electron beam has a minimum diameter for velocity modulating the electron beam, a second cavity resonator at the second pole-piece member in proximity to the point at which the electron beam has a minimum diameter and through which the beam passes for extracting energy therefrom, and a collector electrode disposed on the side of the second resonant cavity remote from the electron beam generating means.

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  • Particle Accelerators (AREA)
  • Microwave Tubes (AREA)

Description

March 2, 1965 B. B. VAN IPEREN 3,172,005
BEAM CONVERGENCE IN VELOCITY-MODULATING VALVE Filed Dec. 1, 1960 FIG. 2
INVENTOR B ERNARDUSB. VAN IPEREN United States Patent 7, 3 4 Claims. (Cl.315-S.35)
This invention relates to velocity-modulating tubes in which an electron beam is converged electrostatically to a point inside one of two pole-pieces between which a magnetic field directed axially relative to the electron beam is present.
In a known velocity-modulating tube of the abovementioned type, the magnetic field has a strength such that the electron beam upon reaching the second polepiece has a diameter substantially equal to its diameter at the first pole-piece. Since the diameter of the electron beam is determinative of how small the wavelength may be of the cavity resonator bringing about velocity-modulation in the electronic beam, the oscillations which can be produced or amplified by means of such a velocitymodulating tube have frequencies which are comparatively limited.
An object of the invention is to provide a velocitymodulating tube of the above-mentioned type which permits of obtaining higher frequencies.
According to the invention, in a velocity-modulating tube in which an electron beam is converged electrostatically to a point inside one of two pole-pieces between which a magnetic field directed axially relative to the electron beam is present, the strength of the magnetic field is in connection with the velocity of the electron beam such that the electron beam reaches a minimum diameter at the second pole-piece, while inside or immediately after the pole-piece means are provided for bringing about velocity-modulation in the beam and/or extracting energy therefrom.
Since the beam, after having passed through the first pole-piece, decreases still further in diameter, it may coact inside or after the second pole-piece with a cavity resonator of a considerably shorter wave-length than in the event that the diameter of the beam would have remained unchanged after the first pole-piece.
As a rule, the invention can be applied in the simplest way to a velocity-modulating tube having only one cavity resonator, i.e. a reflex klystron, but since the decrease in the diameter of the electron beam is not permanent, but repeated periodically, it is alternatively possible to arrange the pole-pieces a little further remote from each other and to mount another cavity resonator between them, resulting in a klystron having two cavity resonators.
The invention will be described with reference to the accompanying drawing in which:
FIGURE 1 is a cross-sectional view of a reflex klystron according to the invention and FIGURE 2 shows a cross-section of a klystron having two cavity resonators.
FIGURE 1 shows pole-pieces 1 and 2 of a permanentmagnetic block 3. A hollow cathode 4 emits with the aid of a focusing electrode 5 and a front side 6 of the pole-piece 1 an electron beam with contours 7 through an aperture 3 provided in pole-piece 1. The minimum diameter is reached approximately at the rear side of the pole-piece 1. Several magnetic lines of force extending from the aperture 8 to the pole-piece 2 are indicated by 9. Due to the fact that the electrons travel at right angles to these lines of force, they are subject to a force along the periphery of the beam at right angles to the 3,172,005 Patented Mar. 2, 1965 direction of travelling, resulting in a circular movement being superimposed on the rectilinear movement. However, due to the circular movement in the axial magnetic field, the electrons encounter forces directed towards the axis and consider-ably decreasing the diameter of the beam. The beam of small diameter passes, at 19, through the gap in a cavity resonator 11 which is made of copper and arranged within the pole-piece 2. After leaving the aperture 10, the electron beam slightly diverges and is reflected by a reflector electrode 12 to the aperture 10 and towards the pole-piece 1. The vacuum closures at the two ends of the reflex klystron are not shown.
The cathode 4 has a negative potential of about 1000 volts and the reflector electrode 12 has a negative potential of 300 volts relative to the pole-pieces 1 and 2. The voltage of the focusing electrode 5 differs but slightly from that of the cathode 4. The diameter of a hollow cathode 4 is 0.8 mm. The aperture 8 has a minimum diameter of 0.3 mm. and the aperture 10 in the cavity resonator 11 has a diameter of 0.1 mm. The electron current from the cathode is 30 mamps. The cavity resonator 11 has dimensions such that the oscillations produced by the reflex klystron have a wave-length of about 2.5 mms.
The spacing between the adjacent sides of the polepieces is 1.3 mm. and the magnetic field in the axis of the beam has a strength of about 3300 gauss.
FIGURE 2 differs from FIGURE 1 only insofar that between the two pole-pieces, which now have a spacing of 4 mms. between them, another cavity resonator 13 having an aperture 14 is provided at the area where the electron beam has a minimum diameter for thefirst time. The second minimum of the diameter falls again in the aperture 10 of the cavity resonator 11. The cavity resonator 13 is supported by means of a copper block 15 which bears on the pole-piece 2. The collector electrode for the electrons having passed the cavity resonator 11 is indicated by 16. The wave-guides for the supply and discharge of the energy in the cavity resonators are not shown.
What is claimed is:
1. A velocity modulating tube comprising means to generate and project an electron beam along a given direction, first and second pole-piece members each having an aperture through which the electron beam passes, focussing means for converging the electron beam to a point within the aperture of one of said pole-pieces, said pole-pieces defining therebetween a magnetic field coaxial with the electron beam having a strength at which the electron beam has a minimum diameter at the second pole-piece member, and means in proximity to the second pole-piece member for selectively velocity modulating the electron beam and extracting energy therefrom.
2. A velocity modulating tube comprising means to generate and project an electron beam along a given direction, first and second pole-piece members each having an aperture through which the electron beam passes, focussing means for converging the electron beam to a point within the aperture of one of said pole-pieces, said polepieces being spaced apart and defining therebetween a magnetic field coaxial with the electron beam having a strength at which the electron beam has a minimum diameter between the pole-piece members, a first resonant cavity between the pole-pieces through which the beam passes and is velocity modulated, and a second cavity resonator in the proximity of the point at which the electron beam has a minimum diameter through which the beam passes and energy is extracted therefrom.
3. A velocity modulating tube comprising means to generate and project an electron beam along a given direction, first and second pole-piece members each having an aperture through which the electron beam passes, electrostatic focussing means for converging the electron beam to a point within the aperture of one of said polepieces, said pole-pieces defining therebetween a magnetic field coaxial with the electron beam having a strength at which the electron beam has a minimum diameter at the second pole-piece member, a cavity resonator in proximity to the point at which the beam has a minimum diameter and for velocity modulating and extracting energy from the beam, and a reflector electrode positioned after said second pole-piece for reflecting electrons in said beam passing through the aperture in the second pole-piece member.
4. A velocity modulating tube comprising means to generate and project an electron beam along a given direction, first and second pole-piece members each having an aperture through which the electron beam passes, electrostatic focussing means for converging the electron beam to a point within the aperture of one of said polepieces, said pole-pieces being spaced apart and defining therebetween a magnetic field coaxial with the electron beam having a strength at which the electron beam has a minimum diameter between the pole-pieces and at the second pole-piece member, a cavity resonator in the proximity of the point between the pole-pieces at which the electron beam has a minimum diameter for velocity modulating the electron beam, a second cavity resonator at the second pole-piece member in proximity to the point at which the electron beam has a minimum diameter and through which the beam passes for extracting energy therefrom, and a collector electrode disposed on the side of the second resonant cavity remote from the electron beam generating means.
References Cited in the file of this patent UNITED STATES PATENTS 2,687,490 Rich et al. Aug. 24, 1954 2,707,758 Wang May 3, 1955 2,812,467 Kompfner Nov. 5, 1957 2,829,299 Beck Apr. 1, 1958

Claims (1)

1. A VELOCITY MODULATING TUBE COMPRISING MEANS TO GENERATE AND PROJECT AN ELECTRON BEAM ALONG A GIVEN DIRECTION, FIRST AND SECOND POLE-PIECE MEMBERS EACH HAVING AN APERTURE THROUGH WHICH THE ELECTRON BEAM PASSES, FOCUSSING MEANS FOR CONVERGING THE ELECTRON BEAM TO A POINT WITHIN THE APERTURE OF ONE OF SAID POLE-PIECES, SAID POLE-PIECES DEFINING THEREBETWEEN A MAGNETIC FIELD COAXIAL WITH THE ELECTRON BEAM HAVING A STRENGTH AT WHICH THE ELECTRON BEAM HAS A MINIMUM DIAMETER AT THE SECOND POLE-PIECE MEMBER, AND MEANS IN PROXIMITY TO THE SECOND POLE-PIECE MEMBER FOR SELECTIVELY VELOCITY MODULATING THE ELECTRON BEAM AND EXTRACTING ENERGY THEREFROM.
US72902A 1960-01-08 1960-12-01 Beam convergence in velocitymodulating valve Expired - Lifetime US3172005A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3846665A (en) * 1972-06-27 1974-11-05 Thomson Csf Velocity modulation tube with frequency multiplication for the continuous generation of high power outputs

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2687490A (en) * 1949-09-22 1954-08-24 Sperry Corp High-frequency beam tube device
US2707758A (en) * 1950-12-19 1955-05-03 Sperry Corp Travelling wave tube
US2812467A (en) * 1952-10-10 1957-11-05 Bell Telephone Labor Inc Electron beam system
US2829299A (en) * 1949-08-12 1958-04-01 Int Standard Electric Corp Electron discharge devices

Family Cites Families (4)

* 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
FR940291A (en) * 1947-01-22 1948-12-08 Materiel Telephonique Slip electrode for wideband velocity modulation amplifier
US2567674A (en) * 1949-11-08 1951-09-11 Rca Corp Velocity modulated electron discharge device
GB813104A (en) * 1955-08-10 1959-05-06 Varian Associates Velocity-modulation electron tube apparatus

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2829299A (en) * 1949-08-12 1958-04-01 Int Standard Electric Corp Electron discharge devices
US2687490A (en) * 1949-09-22 1954-08-24 Sperry Corp High-frequency beam tube device
US2707758A (en) * 1950-12-19 1955-05-03 Sperry Corp Travelling wave tube
US2812467A (en) * 1952-10-10 1957-11-05 Bell Telephone Labor Inc Electron beam system

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3846665A (en) * 1972-06-27 1974-11-05 Thomson Csf Velocity modulation tube with frequency multiplication for the continuous generation of high power outputs

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DE1241537B (en) 1967-06-01

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