US3237059A - Permanent magnet system for producing a magnetic field for the focused passage of a beam of electrons - Google Patents

Permanent magnet system for producing a magnetic field for the focused passage of a beam of electrons Download PDF

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Publication number
US3237059A
US3237059A US310802A US31080263A US3237059A US 3237059 A US3237059 A US 3237059A US 310802 A US310802 A US 310802A US 31080263 A US31080263 A US 31080263A US 3237059 A US3237059 A US 3237059A
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United States
Prior art keywords
magnetic
poles
permanent
magnet
permanent magnets
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Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
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US310802A
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English (en)
Inventor
Meyerer Paul
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
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
    • H01J23/08—Focusing arrangements, e.g. for concentrating stream of electrons, for preventing spreading of stream
    • H01J23/087—Magnetic focusing arrangements
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F7/00—Magnets
    • H01F7/02—Permanent magnets [PM]
    • H01F7/0273—Magnetic circuits with PM for magnetic field generation
    • H01F7/0278—Magnetic circuits with PM for magnetic field generation for generating uniform fields, focusing, deflecting electrically charged particles
    • 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

Definitions

  • the present invention relates vto a system of permanent magnets for producing a substantially homogeneous magnetic field for the focused passage of a beam of electrons over an extended path, especially for high power travelingwave tubes, comprising permanent magnets which are arranged with axial symmetry about the axis of the system, and are magnetized radially to the axis of the system, and the outwardly disposed poles of which are magnetically short-circuited in the longitudinal direction of the system, there being provided between the magnet poles of opposite polarity arranged at the two ends of the system in the longitudinal direction thereof, further magnet poles which are respectively of the same polarity up to the center of the system, which magnet poles efiect a homogenizing of the course of the magnetic field, at least in the region of said magnet poles.
  • Magnetic coils have the disadvantage that they consume electric power. The tendency therefore has been increasingly toward using permanent magnet systems for the focused guiding of the beam of electrons of a velocitymodulated tube.
  • Tubular and barrel-magnets are known for use as permanent magnets for the production of a substantially homogeneous magnetic field for the focused guiding of a beam of electrons.
  • the object of the present invention is to create a system of permanent magnets for obtaining a substantially homogeneous magnetic field for the focused passage of a-beam of electrons over an extended path, and particularly for highpower traveling wave tubes, in which the Weight of the magnet, for a given useful flux, can be substantially reduced as compared with the known permanent magnets.
  • a permanent-magnet system of the initially mentioned kind in which, in accordance with the invention, the permanent magnets form on their side facing the system axis, a plurality of magnetic poles following closely upon each other, the magnetic potential of which decreases in such a manner from the ends toward the center of the system that all lines of force extending from the individual magnetic poles extend inside the system substantially parallel to the system axis.
  • the invention makes it possible to use for the permanent magnets a material which has a low energy content and a very high coercive force (I-I 2000 oersteds).
  • I-I 2000 oersteds very high coercive force
  • the ratio of the magnetic useful flux to the magnetic scattering flux is very high and therefore essentially only the energy requirement of the magnetic useful flux need be covered.
  • material of high coercive force and low energy content there is to be understood a magnet material in which the quotient of the magnetic induction at the operating point B A divided by the magnetic field strength at the operating point H is of the order of magnitude of a one place number.
  • hardmagnetic ferrites or alloys having a platinum-cobalt base are, for instance, known.
  • the known laws of the dimensioning of permanent magnets of a material of high coercive force and low energy content it follows that such permanent magnets are compact, thus resulting in a low magnet volume.
  • the weight of a permanent magnet in accordance with the invention becomes even less since ferrites have a low specific weight.
  • a permanent magnet system in accordance with the invention advantageously consists of permanent magnets which are arranged in close succession, one behind the other, and the lengths of which continuously decrease from the two outer ends toward the center of the system.
  • the individual permanent magnets are, in this connection, as close as possible to each other.
  • a unitary permanent magnet which tapers from the end of the system to the outside of the system in a step-wise, or wedge-shape manner;
  • the permanent magnets which are magnetized radially to the axis of the system may be annular or grouped as magnet bars in star-shape around the axis of the system.
  • FIG. 1 shows a longitudinal section through a permanent magnet system according to the invention
  • FIG. 2 indicates the course of the field of a permanent magnet system according to FIG. 1;
  • FIG. 3 represents an end view of a permanent magnet system according to the invention
  • FIG. 4 is a longitudinal section through the system represented in FIG. 3;
  • FIG. 5 shows a permanent magnet system comprising reinforcing end magnets for supplying the energy requirements caused by unavoidable scattering flux.
  • radially magnetized rings 2 which consist for instance of hard-magnetic ferrite of high coercive force.
  • the height of the individual rings 2 is so dimensioned that their magnetic poles, facing the axis of the system, have a magnetic voltage of such a value that the magnetic lines of potential in the entire inner space of the system of permanent magnets are substantially perpendicular to the axis of the system and have practically the same spacing from each other.
  • This potential pattern is indicated by the lines 3, the numerals which are provided in each case with a positive or negative sign in the magnet poles of the rings 2 facing the magnet axis, representing normalized values of the magnetic voltage.
  • the result is then that all lines of force extending from the individual magnetic poles extend within the system substantially parallel to the axis of the system since, as is known, magnetic lines of force always are at right angles to the lines of potential.
  • the lines 4 indicate how the magnetic lines of flux extend between the two magnetic poles arranged at the ends of the magnet system. The field distribution is in this connection more uniform, the finer the grading of the permanent magnets is effected.
  • FIG. 2 there is shown in FIG. 2 the course of the field of a system of permanent magnets in accordance with FIG. 1, the x-axis of the rectangular coordinate system indicating the path 2 in axial direction of the system and the y-axis indicating the magnetic induction B
  • the full line curve 6 then represents the value of the magnetic field 13 along the axis of the focusing system of FIG. 1.
  • the dashed curve 7 indicates that in the case of a permanent-magnet system in accordance with FIG. 1, the field can be increased by a corresponding increase in the magnetic voltage on the output side of the magnet system, as required at times for traveling-wave tubes of high power.
  • Numerals 11 indicate pole shoes around which are arranged the magnet bars on the two ends of the system and into which a traveling wave tube can be inserted. It may be pointed out that such pole shoes can also be used in permanent magnet systems, such as shown in FIG. 1.
  • FIG. 5 shows an embodiment utilizing this feature.
  • FIG. 5 The permanent magnet system of FIG. 5 is substantally similar to the system shown in FIGS. 3 and 4.
  • the two magnetic bars 12 disposed at the ends are merely reinforced by further magnetic bars 13.
  • FIG. 5 shows both, the case in which the magnetic bars 13 have the same as well as the case in which they have a smaller magnetic voltage than the adjacent magnetic bars 12, depending on how high the energy requirement to cover the outer scattering flux is.
  • the invention is not inherently limited to the illustrated embodiments.
  • the permanent magnets it is not necessary for the permanent magnets to be stepped-down on the inside, as it is possible that they also be stepped down on the outside of the system.
  • the soft-magentic screening covering must have a shape corresponding to the mode of stepping.
  • more than four magnet bars can be grouped in a plane at right angles to the axis of the system in star-shape about such axis. It is likewise possible to use instead of hard-magnetic ferrites, any other suitable and known material of high coercive force and low energy content.
  • a permanent-magnet system for producing substantially homogeneous magnetic field for the focused passage of a beam of electrons over an extended path, particularly for high power traveling-wave tubes, comprising permanent mangents disposed along and arranged with axial symmetry about the axis of the system, said magnets being magnetized radially to the system axis, means at the outer poles of said permanent magnets for magnetically short circuiting such poles in the longitudinal direction of the system, said permanent magnets being so disposed that the poles disposed at one end of the system have a polarity which is opposite to that of the corresponding poles at the other end of the system, said permanent magnets forming further magnetic poles arranged in the longitudinal direction of the systern, between said magnetic poles of opposite polarity arranged at the two ends of the system, the respective further magnetic poles being of the same polarity up to the center of the system and effecting a homogenizing of the course of the magnetic field, at least in the vicinity of said magnet poles, said permanent magnets forming on the side
  • a permanent magnet system wherein the permanent magnets are stepped down stepwise, the outer ends of the permanent magnet lying in a common plane.
  • a permanent magnet system wherein the individual steps are respectively formed by magnet bars arranged in star-shape about the axis of the system, said bars being located one behind the other in the longitudinal direction of the system.
  • a permanent magnet system according to claim 5, wherein the permanent magnets, which are arranged at the two ends of the system, are reinforced by additional magnets which are likewise radially magnetized and which supply the energy for the external scattering flux.
  • a permanent magnet system according to claim 1, wherein the magnetic short-circuiting of the outer poles of the permanent magnets is effected via elongated softiron rails which are connected together to form a housing surrounding the system.

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  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Permanent Field Magnets Of Synchronous Machinery (AREA)
  • Microwave Tubes (AREA)
  • Particle Accelerators (AREA)
US310802A 1962-10-04 1963-09-23 Permanent magnet system for producing a magnetic field for the focused passage of a beam of electrons Expired - Lifetime US3237059A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DES81889A DE1298646B (de) 1962-10-04 1962-10-04 Permanentmagnetisches Fokussierungssystem zur Erzeugung eines wenigstens angenaehert homogenen Magnetfeldes fuer die gebuendelte Fuehrung eines Elektronenstrahls ueber eine groessere Wegstrecke, insbesondere fuer Wanderfeldroehren

Publications (1)

Publication Number Publication Date
US3237059A true US3237059A (en) 1966-02-22

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US310802A Expired - Lifetime US3237059A (en) 1962-10-04 1963-09-23 Permanent magnet system for producing a magnetic field for the focused passage of a beam of electrons

Country Status (6)

Country Link
US (1) US3237059A (enrdf_load_stackoverflow)
DE (1) DE1298646B (enrdf_load_stackoverflow)
DK (1) DK103681C (enrdf_load_stackoverflow)
GB (1) GB1039576A (enrdf_load_stackoverflow)
NL (2) NL298777A (enrdf_load_stackoverflow)
SE (1) SE319241B (enrdf_load_stackoverflow)

Cited By (25)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3436587A (en) * 1965-01-26 1969-04-01 Siemens Ag Permanent magnet system for the generation of a substantially homogeneous magnetic field for the bundled guidance of an electron beam over a relatively long path,especially for traveling wave tubes
US3686527A (en) * 1969-12-12 1972-08-22 Sanders Associates Inc High-speed synthesized field focus coil
US4433270A (en) * 1980-01-28 1984-02-21 Drozdov Sergei S Reversible periodic magnetic focusing system
US4614930A (en) * 1985-03-25 1986-09-30 General Electric Company Radially magnetized cylindrical magnet
US4647887A (en) * 1984-12-24 1987-03-03 The United States Of America As Represented By The Secretary Of The Army Lightweight cladding for magnetic circuits
US4654618A (en) * 1986-05-01 1987-03-31 The United States Of America As Represented By The Secretary Of The Army Confinement of kOe magnetic fields to very small areas in miniature devices
US4658228A (en) * 1986-05-01 1987-04-14 The United States Of America As Represented By The Secreatry Of The Army Confinement of longitudinal, axially symmetric, magnetic fields to annular regions with permanent magnets
US4701737A (en) * 1986-05-30 1987-10-20 The United States Of America As Represented By The Secretary Of The Army Leakage-free, linearly varying axial permanent magnet field source
US4720692A (en) * 1984-10-24 1988-01-19 The United States Of America As Represented By The Secretary Of The Air Force Long, narrow, uniform magnetic field apparatus and method
US4953555A (en) * 1987-10-20 1990-09-04 The United States Of Americas As Represented By The Secretary Of The Army Permanent magnet structure for a nuclear magnetic resonance imager for medical diagnostics
US4999600A (en) * 1986-10-17 1991-03-12 Centre National De La Recherche Scientifique Cylindrical permanent magnet to produce a transversal and uniform induction field
US5014032A (en) * 1986-10-17 1991-05-07 Centre National De La Recherche Scientifique Cylindrical permanent magnet with longitudinal induced field
US5028903A (en) * 1986-10-17 1991-07-02 Centre National De La Recherche Scientifique Spherical permanent magnet with equatorial access
EP0476609A3 (en) * 1990-09-19 1992-11-19 Tdk Corporation Permanent magnet magnetic circuit
US5319339A (en) * 1993-03-08 1994-06-07 The United States Of America As Represented By The Secretary Of The Army Tubular structure having transverse magnetic field with gradient
US5576679A (en) * 1994-10-25 1996-11-19 Shin-Etsu Chemical Co., Ltd. Cylindrical permanent magnet unit suitable for gyrotron
US5786741A (en) * 1995-12-21 1998-07-28 Aura Systems, Inc. Polygon magnet structure for voice coil actuator
US5828173A (en) * 1994-07-09 1998-10-27 Forschungszentrum Karlsruhe Gmbh Magnetic system for gyrotrons forming a wavy magnetic field
US5929732A (en) * 1997-04-17 1999-07-27 Lockheed Martin Corporation Apparatus and method for amplifying a magnetic beam
US20070182264A1 (en) * 2005-09-13 2007-08-09 Lg Electronics Inc. Motor and washing machine including the same
US20090295378A1 (en) * 2008-05-28 2009-12-03 Otto Voegeli Confined field magnet system and method
CN105047355A (zh) * 2015-08-12 2015-11-11 中国科学院电工研究所 一种用于聚焦和引导电子束的圆筒形永磁体系统
RU206633U1 (ru) * 2020-01-28 2021-09-20 Акционерное общество "Научно-производственное предприятие "Исток" имени А.И. Шокина" (АО "НПП "Исток" им. Шокина") Магнитная фокусирующая система
US20210405138A1 (en) * 2018-11-29 2021-12-30 Epsitau Ltd. Lightweight asymmetric magnet arrays with theta magnet rings
US11448715B2 (en) * 2018-09-03 2022-09-20 Singapore University Of Technology And Design Permanent magnet system and method of forming thereof

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3518852A1 (de) * 1985-05-23 1986-11-27 Siemens AG, 1000 Berlin und 8000 München Magnet eines kernspintomographen

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB770133A (en) * 1954-06-03 1957-03-13 Csf Improvements in or relating to permanent magnets
US2876373A (en) * 1956-03-01 1959-03-03 Siemens Ag Magnet system for the focusing of electron beams

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE725473C (de) * 1935-07-23 1942-10-08 Fernseh Gmbh Elektronensammelspule
NL218874A (enrdf_load_stackoverflow) * 1957-07-11

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB770133A (en) * 1954-06-03 1957-03-13 Csf Improvements in or relating to permanent magnets
US2876373A (en) * 1956-03-01 1959-03-03 Siemens Ag Magnet system for the focusing of electron beams

Cited By (32)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3436587A (en) * 1965-01-26 1969-04-01 Siemens Ag Permanent magnet system for the generation of a substantially homogeneous magnetic field for the bundled guidance of an electron beam over a relatively long path,especially for traveling wave tubes
US3686527A (en) * 1969-12-12 1972-08-22 Sanders Associates Inc High-speed synthesized field focus coil
US4433270A (en) * 1980-01-28 1984-02-21 Drozdov Sergei S Reversible periodic magnetic focusing system
US4720692A (en) * 1984-10-24 1988-01-19 The United States Of America As Represented By The Secretary Of The Air Force Long, narrow, uniform magnetic field apparatus and method
US4647887A (en) * 1984-12-24 1987-03-03 The United States Of America As Represented By The Secretary Of The Army Lightweight cladding for magnetic circuits
US4614930A (en) * 1985-03-25 1986-09-30 General Electric Company Radially magnetized cylindrical magnet
US4654618A (en) * 1986-05-01 1987-03-31 The United States Of America As Represented By The Secretary Of The Army Confinement of kOe magnetic fields to very small areas in miniature devices
US4658228A (en) * 1986-05-01 1987-04-14 The United States Of America As Represented By The Secreatry Of The Army Confinement of longitudinal, axially symmetric, magnetic fields to annular regions with permanent magnets
US4701737A (en) * 1986-05-30 1987-10-20 The United States Of America As Represented By The Secretary Of The Army Leakage-free, linearly varying axial permanent magnet field source
US4999600A (en) * 1986-10-17 1991-03-12 Centre National De La Recherche Scientifique Cylindrical permanent magnet to produce a transversal and uniform induction field
US5014032A (en) * 1986-10-17 1991-05-07 Centre National De La Recherche Scientifique Cylindrical permanent magnet with longitudinal induced field
US5028903A (en) * 1986-10-17 1991-07-02 Centre National De La Recherche Scientifique Spherical permanent magnet with equatorial access
US4953555A (en) * 1987-10-20 1990-09-04 The United States Of Americas As Represented By The Secretary Of The Army Permanent magnet structure for a nuclear magnetic resonance imager for medical diagnostics
EP0476609A3 (en) * 1990-09-19 1992-11-19 Tdk Corporation Permanent magnet magnetic circuit
US5319339A (en) * 1993-03-08 1994-06-07 The United States Of America As Represented By The Secretary Of The Army Tubular structure having transverse magnetic field with gradient
US5347254A (en) * 1993-03-08 1994-09-13 The United States Of America As Represented By The Secretary Of The Army Tubular structure having transverse magnetic field with gradient
US5828173A (en) * 1994-07-09 1998-10-27 Forschungszentrum Karlsruhe Gmbh Magnetic system for gyrotrons forming a wavy magnetic field
US5576679A (en) * 1994-10-25 1996-11-19 Shin-Etsu Chemical Co., Ltd. Cylindrical permanent magnet unit suitable for gyrotron
US5786741A (en) * 1995-12-21 1998-07-28 Aura Systems, Inc. Polygon magnet structure for voice coil actuator
US5929732A (en) * 1997-04-17 1999-07-27 Lockheed Martin Corporation Apparatus and method for amplifying a magnetic beam
US20070182264A1 (en) * 2005-09-13 2007-08-09 Lg Electronics Inc. Motor and washing machine including the same
US7405502B2 (en) * 2005-09-13 2008-07-29 Lg Electronics Inc. Motor and washing machine including the same
US8294543B2 (en) 2008-05-28 2012-10-23 Otto Voegeli Confined field magnet system and method
US8179220B2 (en) * 2008-05-28 2012-05-15 Otto Voegeli Confined field magnet system and method
US20090295378A1 (en) * 2008-05-28 2009-12-03 Otto Voegeli Confined field magnet system and method
CN105047355A (zh) * 2015-08-12 2015-11-11 中国科学院电工研究所 一种用于聚焦和引导电子束的圆筒形永磁体系统
US11448715B2 (en) * 2018-09-03 2022-09-20 Singapore University Of Technology And Design Permanent magnet system and method of forming thereof
US20210405138A1 (en) * 2018-11-29 2021-12-30 Epsitau Ltd. Lightweight asymmetric magnet arrays with theta magnet rings
US11875937B2 (en) * 2018-11-29 2024-01-16 Epsitau Ltd. Lightweight asymmetric array of magnet elements
US20240221984A1 (en) * 2018-11-29 2024-07-04 Epsitau Ltd. Lightweight asymmetric array of magnet elements
US12205765B2 (en) * 2018-11-29 2025-01-21 Epsitau Ltd. Lightweight asymmetric array of magnet elements
RU206633U1 (ru) * 2020-01-28 2021-09-20 Акционерное общество "Научно-производственное предприятие "Исток" имени А.И. Шокина" (АО "НПП "Исток" им. Шокина") Магнитная фокусирующая система

Also Published As

Publication number Publication date
NL133615C (enrdf_load_stackoverflow)
NL298777A (enrdf_load_stackoverflow) 1900-01-01
SE319241B (enrdf_load_stackoverflow) 1970-01-12
DE1298646B (de) 1969-07-03
DK103681C (da) 1966-02-07
GB1039576A (en) 1966-08-17

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