US3172008A - Device for concentrating the electron beam in a high-power klystron comprising more than two cavity resonators - Google Patents

Device for concentrating the electron beam in a high-power klystron comprising more than two cavity resonators Download PDF

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US3172008A
US3172008A US200388A US20038862A US3172008A US 3172008 A US3172008 A US 3172008A US 200388 A US200388 A US 200388A US 20038862 A US20038862 A US 20038862A US 3172008 A US3172008 A US 3172008A
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drift tube
electron beam
cavity resonators
concentrating
magnetic
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US200388A
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Schmidt Wolfgang
Schumann Gerhard
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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
    • 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
    • H01J23/087—Magnetic focusing arrangements
    • H01J23/0873—Magnetic focusing arrangements with at least one axial-field reversal along the interaction space, e.g. P.P.M. focusing

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  • the invention relates to a device for concentrating the electron beam of a high-power klystron having more than two cavity resonators, in with the magnetic fields, alternating their directions, are produced by means of permanent magnets with pole shoes contacting the drift tube parts of the klystron.
  • FIG. 1 Devices of the kind set forth are known and shown diagrammatically in FIG. 1.
  • the alternating magnetic fields 3 travel between pole shoes 5 and the permanent magnets are designated by 7.
  • the direction of movement of the electron beam is denoted by 1.
  • highpower klystrons having more than two cavity resonators which usually operate on comparatively low frequencies, such a structure brings about, however, inconvenient dimensions and weights, not only of the assembly as a whole but also of the component parts, since in this case the large resonators must be bridged by the soft-iron yokes between the pole shoes 5 and the magnets 7.
  • a further great disadvantage of such a concentration by means of magnetic single lenses would be that just in the region of the inductance gaps and modulation gaps 15 of the cavity resonators 17 the diameter of the electron beam has a minimum, which will be seen from the drawing by the cross-hatched section of the electron beam. Because of the small beam diameter a heavy coupling between the electron beam and the cavity resonators would not be possible. This is, howeverypossible, if the diameter of the electron beam approaches more closely that of the interaction gap.
  • the permanent magnets are arranged, in accordance with the invention, at a given distance from the Walls of the drift tube outside the cooling members and are connected by magnetic yokes with the pole shoes, which extend on either side of the yokes in an axial direction over a distance such that axial magnetic fields are produced also in the spaces inside the cavity resonators, which fields have the opposite direction as compared with those of the drift tube parts and have approximately the same intensity.
  • the electron beam may, moreover, have a maximum diameter in the interaction space inside the cavity resonators, so that a heavy coupling between the beam and the cavity resonators is possible.
  • a simple control of the magnetic field intensity may be obtained when the magnets consist of magnetic columns composed of parts, which are relatively slidable, so that a more or less strong leakage field can be adjusted.
  • the two pole shoes may be at different potentials, which is advantageous with certain tubes.
  • the magnetic columns may be connected with the yokes, which are fastened by means of bolts or the like to the pole shoes.
  • the arrangement according to the invention when sintered, oxidic magnets are employed, consists in that the influence of temperature of the air-cooled parts on the magnets is only slight, so that from this side the magnetic field is little affected by temperature.
  • FIG. 3 shows diagrammatically a longitudinal sectional view of a device according to the invention.
  • FIG. 4 is a plan view and FIG. 5 is a cross sectional view.
  • resonators 17 are arranged between the parts 11 of the drift tube.
  • the parts 11 of the drift tube are provided with cooling vanes 19.
  • the direction of travel of the cooling air is indicated by arrows 20.
  • pole shoes 25 which are connected via soft-iron yokes 27, with the magnetic columns 29, shown diagrammatically.
  • These columns 29 are disposed towards the outer side to an extent such that they do not hinder the cooling operation.
  • the columns 29 consist of stacked, oxidic magnets.
  • magnetic fields B are produced in the direction of travel of the electron beam 1, if the magnetic columns 29 are all oriented in the same direction. However, magnetic fields B in opposite direction are produced at the same time in the high-frequency interaction spaces 34 away from the pole shoes 25. Because of the periodic magnetic field along the electron beam 1 the variations in diameter of the beam are considerably smaller than in the arrangement of FIG. 2; in the regions 34 the electron beam has approximately its maximum diameter, so that a fixed coupling with the cavity resonators is possible.
  • the same intensity of the magnetic fields B and B is obtained by the choice of the pole shoe parts c and d on either side of the yokes 27, so that the lengths a and b of the magnetic field portions in the drift tube and in the cavity resonator respectively can be adjusted.
  • the magnetic yokes comprise parts 37, which are connected with the pole shoes 25, and parts 43, between which parts the magnetic columns are arranged, which are provided with flanges 39 and 41 respectively of non-magnetic material.
  • the magnetic columns consist of two discs 45, glued to the yoke parts 43 and having arranged between them a disc 47, which is slidable along guide rods 49.
  • connecting rods 50 provided with screw threads, are coupled with screw-threaded bars 51, which can be turned by means of a hand-wheel 53.
  • the two halves of the screw-threaded bar 51 are intercoupled at 55.
  • the device according to the invention may be employed with klystrons having a resonator diameter of 100 cms.; in the case of four resonators the overall length is 180 cms.
  • a device for concentrating an electron beam in a drift tube of a klystron having atleast three cavity, resonators comprising means to cool the drift tube, means for producing magnetic fields in the drift tube alternating in direction between the cavity resonators, said magnetic field producing means including permanent magnets posia tioned' beyond the cooling means and spaced" from the drift tube, pole-pieces adjacent to portions of the drift tube between successive cavity resonators, and a yoke of magnetic material connecting each magnet with. a pole piece, each of said pole-pieces extending in the direction of the drift tube on either side of the yoke adi'stan'ce at which an axial magnetic field is. produced in the adjacent cavity resonator having approximately a direction opposite to and having the same intensity as that produced in the adjacent section of the drift tube.

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

Description

March 2, 1965 w, SCHMlDT ETAL 3,172,008
DEVICE FOR CONCENTRATING THE ELECTRON BEAM IN A HIGH-POWER KLYSTRON COMPRISING MORE THAILTWQ CAVITY RESONATORS Filed June 6, 1962 5 Sheets-Sheet l FIGJ FIG.2
INVENTOR WOLFGANG SCHMIDT GERHARD SCHUMANN BY 5;; re.
AGENT March 2, 1965 w. SCHMIDT ETAL 3,172,008
DEVICE FOR CONCENTRATING THE ELECTRON BEAM IN A HIGH-POWER KLYSTRON COMPRISING MORE THAN TWO CAVITY RESONATORS Filed June 6, 1962 5 Sheets-Sheet 2 31 11 34 Bb 31 Ba 34 INVENTOR WOLFGANG scumor GERHARD SCHUMANN AGEN M r 1965 w. SCHMIDT ETAL' 3,172,003
DEVICE FOR CONCENTRATING THE ELECTRON BEAM IN A HIGH-POWER KLYSTRON COMPRISING MORE THAN TWO CAVITY RESONATORS Filed June 6, 1962 5 Sheets-Sheet 3 L0 S 9. 5 LL WOLFGANG SCHMIDT GERHARD SCHUMANN AGENT United States Patent C) DEVICE FOR CONCENTRATING THE ELECTRON 3 Claims. (a. 315-39 The invention relates to a device for concentrating the electron beam of a high-power klystron having more than two cavity resonators, in with the magnetic fields, alternating their directions, are produced by means of permanent magnets with pole shoes contacting the drift tube parts of the klystron.
Devices of the kind set forth are known and shown diagrammatically in FIG. 1. The alternating magnetic fields 3 travel between pole shoes 5 and the permanent magnets are designated by 7. The direction of movement of the electron beam is denoted by 1. With highpower klystrons having more than two cavity resonators, which usually operate on comparatively low frequencies, such a structure brings about, however, inconvenient dimensions and weights, not only of the assembly as a whole but also of the component parts, since in this case the large resonators must be bridged by the soft-iron yokes between the pole shoes 5 and the magnets 7.
With low-power two-cavity klystrons it is known to arrange, between the two cavities, a short, single lens, which is excited by an electro-magnet; this may, however, also be a permanent magnet. With a klystron having more than two cavity resonators the arrangement shown diagrammatically in FIG. 2 would be obtained, in which, like in FIG. 1, 1 designates the direction of travel of the electron beam and 5 the pole shoes. The walls of the drift tube are designated by 11 and the magnetic rings by 13, which produce magnet fields indicated by arrows between the pole shoes 5. However, this arrangement cannot be used in those cases in which the walls of the drift tube must be cooled by air, since this requires cooling vanes of a fairly large diameter with the associated cold-air pipes. A further great disadvantage of such a concentration by means of magnetic single lenses would be that just in the region of the inductance gaps and modulation gaps 15 of the cavity resonators 17 the diameter of the electron beam has a minimum, which will be seen from the drawing by the cross-hatched section of the electron beam. Because of the small beam diameter a heavy coupling between the electron beam and the cavity resonators would not be possible. This is, howeverypossible, if the diameter of the electron beam approaches more closely that of the interaction gap.
In a device for concentrating the electron beam in a high-power klystron having more than two cavity resonators, in which the magnetic fields of alternating directions are produced by means of permanent magnets, having pole shoes contacting the parts of the drift tube of the klystron, the permanent magnets are arranged, in accordance with the invention, at a given distance from the Walls of the drift tube outside the cooling members and are connected by magnetic yokes with the pole shoes, which extend on either side of the yokes in an axial direction over a distance such that axial magnetic fields are produced also in the spaces inside the cavity resonators, which fields have the opposite direction as compared with those of the drift tube parts and have approximately the same intensity. With the structure according to the inice vention a periodic, axial magnetic field is obtained throughout the length of the klystron without the need for bridging the cavity resonators by magnetic yokes. With this arrangement the electron beam may, moreover, have a maximum diameter in the interaction space inside the cavity resonators, so that a heavy coupling between the beam and the cavity resonators is possible.
A simple control of the magnetic field intensity may be obtained when the magnets consist of magnetic columns composed of parts, which are relatively slidable, so that a more or less strong leakage field can be adjusted.
If sintered, oxidic permanent magnets are employed, the two pole shoes may be at different potentials, which is advantageous with certain tubes.
In accordance with the invention the magnetic columns may be connected with the yokes, which are fastened by means of bolts or the like to the pole shoes.
The arrangement according to the invention, when sintered, oxidic magnets are employed, consists in that the influence of temperature of the air-cooled parts on the magnets is only slight, so that from this side the magnetic field is little affected by temperature.
The invention will now be described more fully with reference to FIGS. 3 to 5, of which FIG. 3 shows diagrammatically a longitudinal sectional view of a device according to the invention.
FIG. 4 is a plan view and FIG. 5 is a cross sectional view.
As is shown in FIG. 3 resonators 17 are arranged between the parts 11 of the drift tube. The parts 11 of the drift tube are provided with cooling vanes 19. In FIG. 5 the direction of travel of the cooling air is indicated by arrows 20. Between the outer vane 21 and the walls 23 of the resonators there are arranged pole shoes 25, which are connected via soft-iron yokes 27, with the magnetic columns 29, shown diagrammatically. These columns 29 are disposed towards the outer side to an extent such that they do not hinder the cooling operation. The columns 29 consist of stacked, oxidic magnets.
Inside the drift tube parts 11, in the regions 31, magnetic fields B,, are produced in the direction of travel of the electron beam 1, if the magnetic columns 29 are all oriented in the same direction. However, magnetic fields B in opposite direction are produced at the same time in the high-frequency interaction spaces 34 away from the pole shoes 25. Because of the periodic magnetic field along the electron beam 1 the variations in diameter of the beam are considerably smaller than in the arrangement of FIG. 2; in the regions 34 the electron beam has approximately its maximum diameter, so that a fixed coupling with the cavity resonators is possible. The same intensity of the magnetic fields B and B is obtained by the choice of the pole shoe parts c and d on either side of the yokes 27, so that the lengths a and b of the magnetic field portions in the drift tube and in the cavity resonator respectively can be adjusted.
From FIGS. 4 and 5 it will be seen that the magnetic yokes comprise parts 37, which are connected with the pole shoes 25, and parts 43, between which parts the magnetic columns are arranged, which are provided with flanges 39 and 41 respectively of non-magnetic material. The magnetic columns consist of two discs 45, glued to the yoke parts 43 and having arranged between them a disc 47, which is slidable along guide rods 49. To this end connecting rods 50, provided with screw threads, are coupled with screw-threaded bars 51, which can be turned by means of a hand-wheel 53. The two halves of the screw-threaded bar 51 are intercoupled at 55. By displacing the discs 47 by turning the screw-threaded bar 51, the intensity of the magnetic field can be adjusted.
The device according to the invention may be employed with klystrons having a resonator diameter of 100 cms.; in the case of four resonators the overall length is 180 cms.
What is claimed is: 1. A device for concentrating an electron beam in a drift tube of a klystron having atleast three cavity, resonators comprising means to cool the drift tube, means for producing magnetic fields in the drift tube alternating in direction between the cavity resonators, said magnetic field producing means including permanent magnets posia tioned' beyond the cooling means and spaced" from the drift tube, pole-pieces adjacent to portions of the drift tube between successive cavity resonators, and a yoke of magnetic material connecting each magnet with. a pole piece, each of said pole-pieces extending in the direction of the drift tube on either side of the yoke adi'stan'ce at which an axial magnetic field is. produced in the adjacent cavity resonator having approximately a direction opposite to and having the same intensity as that produced in the adjacent section of the drift tube.
2. A device as claimed in claim 1 in which the magnets are constituted of columns having parts displaceable relative to one another. g
3. A device as claimed in claim2 in which the columns are connected with the yokes and the yokes are secured 2,837,686 Drieschmanetal June 3, 1958 2,940,000 Geisler June 7, 1960 2,993,141 Post July 18, 1961

Claims (1)

1. A DEVICE FOR CONCENTRATING AN ELECTRON BEAM IN A DRIFT TUBE OF A KLYSTRON HAVING AT LEAST THREE CAVITY RESONATORS COMPRISING MEANS TO COOL THE DRIFT TUBE, MEANS FOR PRODUCING MAGNETIC FIELDS IN THT DRIFT TUBE ALTERNATING IN DIRECTION BETWEEN THE CAVITY RESONATORS, SAID MAGNETIC FIELD PRODUCING MEANS INCLUDING PARMANENT MAGNETS POSITIONED BEYOND THE COOLING MEANS AND SPACED FROM THE DRIFT TUBE, POLE-PIECES ADJACENT TO PORTIONS OF THE DRIFT TUBE BETWEEN SUCCESSIVE CAVITY RESONATORS, AND A YOKE OF MAGNETIC MATERIAL CONNECTING EACH MAGNET WITH A POLEPIECE, EACH OF SAID POLE-PIECES EXTENDING IN THE DIRECTION OF THE DRIFT TUBE ON EITHER SIDE OF THE YOKE A DISTANCE AT WHICH
US200388A 1961-06-09 1962-06-06 Device for concentrating the electron beam in a high-power klystron comprising more than two cavity resonators Expired - Lifetime US3172008A (en)

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DEP27312A DE1158183B (en) 1961-06-09 1961-06-09 Permanent magnetic focusing arrangement for a high-performance multi-chamber klystron

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3274430A (en) * 1963-08-01 1966-09-20 Massachusetts Inst Technology Biased-gap klystron
US4433270A (en) * 1980-01-28 1984-02-21 Drozdov Sergei S Reversible periodic magnetic focusing system

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3366904A (en) * 1965-12-14 1968-01-30 Philips Corp High-power multi-stage klystron with adjustable periodic magnetic focussing
GB1164268A (en) * 1966-12-13 1969-09-17 Air Reduction Improvements in or relating to Electron Beam Apparatus.
US5378988A (en) * 1993-01-22 1995-01-03 Pulyer; Yuly M. MRI system having high field strength open access magnet
DE4328232A1 (en) * 1993-08-21 1995-02-23 Licentia Gmbh Electron-beam tube (cathode-ray tube), in particular travelling-wave tube

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2837686A (en) * 1956-10-01 1958-06-03 Eitel Mccullough Inc Klystron apparatus
US2940000A (en) * 1954-07-26 1960-06-07 Applied Radiation Corp Linear electron accelerators
US2993141A (en) * 1958-02-10 1961-07-18 Richard F Post Producing bunched electron beams

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2940000A (en) * 1954-07-26 1960-06-07 Applied Radiation Corp Linear electron accelerators
US2837686A (en) * 1956-10-01 1958-06-03 Eitel Mccullough Inc Klystron apparatus
US2993141A (en) * 1958-02-10 1961-07-18 Richard F Post Producing bunched electron beams

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3274430A (en) * 1963-08-01 1966-09-20 Massachusetts Inst Technology Biased-gap klystron
US4433270A (en) * 1980-01-28 1984-02-21 Drozdov Sergei S Reversible periodic magnetic focusing system

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DE1158183B (en) 1963-11-28
NL279385A (en)
GB953268A (en) 1964-03-25

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