US3188533A - Focussing system for an electron beam incorporating axially magnetized annular magnets - Google Patents

Focussing system for an electron beam incorporating axially magnetized annular magnets Download PDF

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Publication number
US3188533A
US3188533A US259206A US25920663A US3188533A US 3188533 A US3188533 A US 3188533A US 259206 A US259206 A US 259206A US 25920663 A US25920663 A US 25920663A US 3188533 A US3188533 A US 3188533A
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United States
Prior art keywords
pole
focussing
magnets
focussing system
pole shoes
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Expired - Lifetime
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US259206A
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English (en)
Inventor
Bretting Jork
Griem Hans-Jurgen
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Telefunken Patentverwertungs GmbH
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Telefunken Patentverwertungs GmbH
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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
    • H01J23/08—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

Definitions

  • the present invention relates to a system for focussing an electron beam within a vacuum envelope, which focussing system comprises a plurality of coaxially arranged annular magnets, there being ferromagnetic pole shoes of different polarity arranged between alternate pairs of successive magnets.
  • Such a focussing system is particularly adapted for use in travelling-wave tubes.
  • Such focussing systems generally consist of several permanent magnet rings or electromagnetic coils which surround the tube and are arrange-d next to each other, with consecutive magnets having opposing magnetic polarities.
  • One difficulty with the above-described periodic magnetic focussing systems is that the magnetic characteristics of the individual parts thereof, i.e., the actual magnets and the pole shoes arranged therebetween, will fluctuate beyond acceptable tolerances. Consequently, the amplitude and position of the magnetic focussing field within the tube will fluctuate beyond acceptable limits.
  • the disturbance of the magnetic field is particularly marked if, for example, all or part of a magnet is omitted between two pole shoes, as is sometimes necessary if, for' instance, a wave guide for coupling high frequency energy to or decoupling such energy from the tube has to pass through the focussing system.
  • an object of the present invention to provide a focussing system which overcomes the above drawbacks, namely, a focussing system by means of which a more homogeneous focussing field is produced.
  • this is accomplished by interconnecting the poleshoes of like polarity with at least one ferromagnetic yoke. Consequently, the magnetic potential between each two adjacent pole shoes of different polarity will be the same.
  • the balancing effect of the ferromagnetic yokes according to the present invention is sufiiciently large so that an appreciable disturbance of the focussing field is avoided even if one or more magnets is omitted so as to allow one or more wave guides to be connected to the travelling-wave tube.
  • Each yoke is, in practice, made of a material of high permeability having a sutficiently high saturation field strength.
  • FIGURE 1 is a sectional view of one embodiment of a focussing system according to the present invention.
  • FIGURE 1a is a perspective view of a pole shoe according to the present invention, there also being shown a web for connecting the actual pole shoe portion with the yoke.
  • FIGURE 2 is a plan view of another embodiment of a focussing system according to the present invention in which each pole shoe has two webs by which it is connected to yokes.
  • FIGURE 2a is a perspective view of a section of the structure shown in FIGURE 2.
  • FIGURE 3 is a sectional view of a focussing-system according to the present invention in which a coupling line is provided.
  • FIGURE 4 is a perspective View showing the interposition of a coupling line.
  • the focussing system comprising a number of magnet means constituted by axially magnetized, coaxially arranged and spaced-apart ring magnets 1 of alternating polarity, i.e., each magnet (except the end magnets) has a N-pole directed toward a N-pole of one adjacent magnet and a S-pole directed toward a S-pole of the other adjacent magnet.
  • Pole shoes 2 are arranged between the ring magnets.
  • Each pole shoe has a web 3, the position of the Webs 3 being so selected that they join one of two yokes 4 and 5; as shown in FIGURE 1, each of the pole shoes interposed between two N-poles has its web connected to yoke 4 while each of the pole shoes interposed between two S-poles has its web connected to yoke 5.
  • each pole shoe has at its inner periphery an enlarged pole shoe portion surface 6 and two laterally extending flanges 7 (FIGURE 1a); in this way, the ring magnets 1 may simply be slipped over the flanges so that the pole shoes serve also as the mechanical mounting means for holding the ring magnets in place.
  • one or more ring magnets can be'omitted, for example the two end rings, so as to accommodate hollow wave guides by means of which the travelling-wave tube is coupled to another component, such as a source of high-frequency energy.
  • the pole shoes are in the form of rectangular plates 21 provided with an opening 22 through which is inserted the tube that is to be focussed.
  • the pole shoes 21 and 23, shown as being angularly displaced by represent pole shoes of opposite polarity.
  • the webs of pole shoes 23 (only one of which is illustrated) are connected by two diametrically opposite yokes 25 while the webs of the pole shoes 21 (of which, likewise, only one is shown) are connected by two diametrically opposite yokes 25.
  • the ferromagnetic yoke means will generally be arranged exteriorly of the outer periphery of the magnets, as shown in the above-described two embodiments.
  • the invention has been found to be particularly advantageous when the magnets are axially magnetized permanent magnets.
  • the pole shoes between the magnets can be of any suitable configuration.
  • the pole shoes are connected with their respective yokes by means of ferromagnetic webs which are at least magnetically connected with the pole shoes.
  • the focussing system comprises magnets 35 and 38 arranged with alternate illustrated.
  • the outer periphery of the rings engages the yoke or yokes 34; as shown in FIGURE 3, the outer pe riphery of the radially magnetized ring is a N-pole, as are the yokes 34, so that the outer periphery of ring 32 isin contact with a yoke of like polarity.
  • the inner periphery of the ring 32 is providedwith a pole shoe ring 39.
  • each of said magnet means comprises an electromagnetic coil.
  • each of said magnet means comprises a permanent magnet.
  • said pole shoes encompass the vacuum envelope.
  • pole shoes comprise a pole shoe portion and at least one web for connecting the respective pole shoe portion with the respective yoke means.
  • each of said yoke means comprises two yokes
  • each of said pole shoes comprises a pole shoe portion tensity of this ring 32.
  • the shunt 33 will be suitably supported, e.g., by a plastic ring 33a interposed between the shunt and the yokes 34.
  • FIGURE 4 shows a hollow conductor 47 arranged next to a pole shoe 41 provided with a web 43.
  • the pole shoe is fashioned as shown in FIGURE 1a, except that it has a flange 7 only on that side which faces away from the hollow conductor 47, thereby to leave space for the conductor.
  • the diametrically opposite yokes 44 and 45 are of different polarity. Of the permanent ring magnets, only magnet 42 is visible.
  • a system for focussing an electron beam within the envelope comprising, in combination:
  • first yoke means magnetically connecting said set of first pole shoes to each other;
  • said focussing system further comprises'two radially magnetized permanent ring magnets arranged coaxially with said set of magnet means; said ring magnets being located adjacent the first and the last of said set of magnet means,
  • eachof said ring magnets being magnetically connected with the particular yoke which is of the same polarity as the respective outer periphery.
  • a focussing system as defined in claim 10 wherein a high-frequency coupling line is arranged between one of said ring magnets and the nearest of said magnet means. 12. A focussing system as defined in claim 10 wherein said focussing system further comprises magnetic shunt means arranged adjacent said ring magnets.
  • said holding means comprise annular flanges integral with said pole shoes, said magnet means being permanent magnet rings which encompass said flanges so as to be held thereby.

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US259206A 1962-02-23 1963-02-18 Focussing system for an electron beam incorporating axially magnetized annular magnets Expired - Lifetime US3188533A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DET21644A DE1246891B (de) 1962-02-23 1962-02-23 Magnetische Fokussierungsanordnung zur gebuendelten Fuehrung eines Elektronenstrahls, insbesondere fuer Wanderfeldroehren

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US3188533A true US3188533A (en) 1965-06-08

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US259206A Expired - Lifetime US3188533A (en) 1962-02-23 1963-02-18 Focussing system for an electron beam incorporating axially magnetized annular magnets

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DE (1) DE1246891B (de)
GB (1) GB980119A (de)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3334264A (en) * 1963-07-01 1967-08-01 Gen Electric Beam focusing magnet system
US4404494A (en) * 1980-04-21 1983-09-13 Siemens Aktiengesellschaft Travelling wave tube with periodic-permanent magnet focusing system
US5332947A (en) * 1992-05-13 1994-07-26 Litton Systems, Inc. Integral polepiece RF amplification tube for millimeter wave frequencies
US5332948A (en) * 1992-05-13 1994-07-26 Litton Systems, Inc. X-z geometry periodic permanent magnet focusing system

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3014404C2 (de) * 1979-04-11 1985-04-18 Nippon Electric Co., Ltd., Tokio/Tokyo Lauffeldröhre

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2876373A (en) * 1956-03-01 1959-03-03 Siemens Ag Magnet system for the focusing of electron beams
US2991382A (en) * 1958-03-20 1961-07-04 Nippon Electric Co Electron beam tube focusing device

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2844754A (en) * 1953-04-29 1958-07-22 Bell Telephone Labor Inc Electron beam focusing system
FR1212354A (fr) * 1957-10-10 1960-03-23 Thomson Houston Comp Francaise Dispositif d'échange d'énergie en haute fréquence

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2876373A (en) * 1956-03-01 1959-03-03 Siemens Ag Magnet system for the focusing of electron beams
US2991382A (en) * 1958-03-20 1961-07-04 Nippon Electric Co Electron beam tube focusing device

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3334264A (en) * 1963-07-01 1967-08-01 Gen Electric Beam focusing magnet system
US4404494A (en) * 1980-04-21 1983-09-13 Siemens Aktiengesellschaft Travelling wave tube with periodic-permanent magnet focusing system
US5332947A (en) * 1992-05-13 1994-07-26 Litton Systems, Inc. Integral polepiece RF amplification tube for millimeter wave frequencies
US5332948A (en) * 1992-05-13 1994-07-26 Litton Systems, Inc. X-z geometry periodic permanent magnet focusing system
US5534750A (en) * 1992-05-13 1996-07-09 Litton Systems, Inc. Integral polepiece magnetic focusing system having enhanced gain and transmission

Also Published As

Publication number Publication date
GB980119A (en) 1965-01-13
DE1246891B (de) 1967-08-10

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