US3373388A - Permanent magnet system for the generation of at least two opposite magnetic fields lying one behind the other for the bundled guidance of an electron beam, especially for traveling wave tubes - Google Patents

Permanent magnet system for the generation of at least two opposite magnetic fields lying one behind the other for the bundled guidance of an electron beam, especially for traveling wave tubes Download PDF

Info

Publication number
US3373388A
US3373388A US522059A US52205966A US3373388A US 3373388 A US3373388 A US 3373388A US 522059 A US522059 A US 522059A US 52205966 A US52205966 A US 52205966A US 3373388 A US3373388 A US 3373388A
Authority
US
United States
Prior art keywords
magnetic
permanent magnets
permanent magnet
electron beam
magnet system
Prior art date
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
Application number
US522059A
Other languages
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 AG
Siemens Corp
Original Assignee
Siemens Corp
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Siemens Corp filed Critical Siemens Corp
Application granted granted Critical
Publication of US3373388A publication Critical patent/US3373388A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • 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

  • ABSTRACT OF THE DISCLOSURE A permanent magnet array for a so-called reversed field focusing for travelling wave tubes with permanent magnets symmetrically arranged relative to the system axis which according to the invention are arranged in a closed series one behind the other, wherein the expansion of the magnets decreases uniformly and perpendicularly to the system axis from the middle of the closed series to its two ends, the magnets particularly consisting of a material with a high coercive force.
  • the invention relates to a permanent magnet system for the generation of at least two magnetic fields directed oppositely to one another and lying in succession in the longitudinal direction of the system, for the bundled guidance of an electron beam over a relatively long path interval, especially for traveling wave tubes, with permanent magnets symmetrically arranged relative to the system axis, which are magnetized in planes perpendicular to the system axis, and in which the poles turned away from the system axis are magnetically connected with one another by soft iron bridge members, which are provided, at least on the two end faces of the system, with soft iron parts extending toward the system axis, which form in each case a soft magnetic diaphragm or wall.
  • the electron beam In electron beam tubes for the amplification and generation of very high frequencies, especially in traveling wave tubes, the electron beam, as is well known, must be conducted in bundled form over a relatively long path interval.
  • magnetic focusing devices are known, by means of which there is generated in the interior of the discharge vessel of the tube along the discharge path either a homogeneous or an alternating magnetic field.
  • This permanent magnet arrangement has at its exterior a strong magnetic scatter field which does not contribute to the bundling of the electron beam and, consequently, again requires an increase of the magnet weight. Moreover, the considerable external scatter field has to be magnetically shielded with respect to other adjacent highfrequency devices.
  • Another known arrangement for the bundled conduction of an electron beam of a traveling wave tube, with the aid of several homogeneous magnetic fields lying in succession in beam direction, consists of permanent magnets which are arranged between the ends of the delay line of the tube in at least one plane perpendicular to the electron beam.
  • the poles of the permanent magnets facing away from the electron beam are connected by a soft iron sheet metal body extending along the delay line of the tube and somewhat beyond the delay line.
  • This soft iron sheet metal body which is disposed symmetrically with respect to the system axis, is closed off at its end face with soft plates which extend as far as the vacuum shell of the tube.
  • the magnet poles adjacent to the electron beam and the soft iron plates mounted on the ends of the soft iron sheets metal body are magnetically connected with one another by a soft iron cylinder arranged coaxially with the beam axis.
  • a soft iron cylinder arranged coaxially with the beam axis.
  • the invention has as its basic problem that of creating a permanent magnet system for the generation of at least two oppositely directed magnetic fields lying in successive sion in longitudinal direction of the electron beam (reversal field) for the bundled guidance of the electron beam of highest-frequency tubes, in which system the magnetic scatter flux is low in proportion to the useful flux.
  • the permanent magnets be disposed between two soft magnetic diaphragms or walls, and arranged one behind the other in a closed series with the magnetic potential of the permanent magnets decreasing from the middle of the closed series to its two ends, the poles of the permanent magnets adjacent to the system axis all being of like polarity.
  • a permanent magnet system for the generation of a homogeneous magnetic field for the bundled guidance of an electrom' beam over a relatively long path interval it is a known practice, per se, to arrange, in succession, permanent magnets disposed perpendicularly to the system axis and magnetized in a closed series, in order to achieve a low weight of the magnet system.
  • the magnetic potential of the permanent magnets uniformly diminishes from the two ends of the system toward the middle of the system.
  • a further important difference of this known arrangement from a permanent magnet system according to the present invention lies in the feature that the poles of the permanent magnets adjacent to the system axis are of the same designation merely from the end faces of the system to the middle thereof.
  • a permanent magnet system according to the invention presents not only the advantage that the ratio of useful magnetic flux to magnetic scatter flux is very good, but moreover, through the spatial arrangement of the permanent magnets, the coupling and decoupling lines which in a traveling wave tube are ordinarily arranged at the two ends of the delay line, can be spatially well housed in the system without any particular difficulties.
  • the permanent magnets themselves advantageously consist of a hard magnetic ferrite material which, as compared to the nickel-iron-cobalt alloys usual for permanent magnets, have a low specific gravity.
  • the permanent magnets of a system according to the invention are preferably so dimensioned that the magnetic potential of the permanent magnets decreases from the middle of the closed series to their two ends approximately proportionately with the path distance in longitudinal direction of the system. It is thereby achieved that the individual magnetic fields lying one behind the other are essentially homogeneous as is normally the case in a focusing with a reversal field. It is also possible, however, through appropriate choice of the potentials, to achieve a course of the magnetic induction in the individual magnetic zones, in particular increases in field strength if, in certain cases of application this is desired, whereby such course is not fully homogeneous.
  • FIG. 1 is a longitudinal section of a permanent magnet system, according to the invention.
  • FIG. 2 is a transverse section taken approximately on the line 11-11 of FIG. 1;
  • FIG. 3 illustrates the field course of the permanent magnet system of FIG. 1, and is oriented with respect to the latter whereby the values illustrated correspond to the respective points along the system axis;
  • FIG. 4 is a longitudinal section, similar to FIG. 1, of a modification of the invention.
  • FIG. 5 is a transverse section taken approximately on the line VV of FIG. 4;
  • FIG. 6 illustrates the field course of the construction of FIGS. 4 and 5, and is oriented with respect to FIG. 4.
  • the reference numeral 1 designates block-shaped permanent magnets which are magnetized perpendicularly to the longitudinal axis of the magnet system and consist preferably of a material of high coercive strength (H l50O oe.), for example, a hard magnetic ferrite.
  • the permanent magnets 1 are arranged one behind the other in four closed series, which symmetrically surround the system axis.
  • the ends of permanent magnets 1 turned away from the system axis lie in a common plane, while the ends of the permanent magnets adjacent to the system axis are offset stepwise with respect to one another.
  • the graduation is so carried out that the magnetic potential of the permanent magnets 1 uniformly decreases from the middle of the closed series to their two ends, in which arrangement all of the poles of the permanent magnets adjacent to the system axis are of like polarity.
  • the poles of the permanent magnets 1 turned away from the system axis engage soft iron bridge members 2 which are connected with one another to form a shield casing having a square cross section.
  • Such shielding casing is provided at its end face with soft iron plates which extend toward the system axis and there form in each case a soft magnetic diaphragm or wall 3.
  • FIG. 3 By means of two diaphragms 3 there is produced along the axis of the system a magnetic field with a reversal of the magnetic induction in the middle of the system.
  • FIG. 1 Beneath FIG. 1 there is represented in FIG. 3 the field course which is achieved in a permanent magnet system according to FIGS. 1 and 2.
  • the abscissa of the rectangular coordinate system represents the path z in longitudinal direction of the system and the ordinate the magnetic induction B
  • the solidly drawn curve 4 represents the value of the magnetic field B along the axis of the focusing system according to FIGS. 1 and 2 with the magnetic potentials there indicated, such magnetic field being a reversal field with two magnetic fields oppositely directed extending one behind the other, which are in each case essentially homogeneous.
  • the broken-line curve 5 indicates that in the individual zones of the reversal field the course of the magnetic field strength on the system axis need not be homogeneous. This can be brought about in a permanent magnet system according to FIGS. 1 and 2 by an arrangement in which the steps between adjacent permanent magnets 1 are not uniformly reduced along the path interval z in a direction perpendicularly to the system axis.
  • FIGS. 4 and 5 illustrate another example of construction of a permanent magnet system according to the invention, in which the permanent magnets 1, as seen in longitudinal direction of the system, form two closed series, between which there is arranged a soft-magnetic diaphragm or wall 3, which extends from the soft iron bridge members 2 perpendicularly toward the system axis.
  • the permanent magnets 1, again in block form, are in each case arranged between two adjacent magnetic diaphragms 3, symmetrical to the system axis, in two closed series 0pposite one another.
  • the soft iron bridge members 2 are provided with the soft iron plates which form the soft magnetic diaphragms 3 and bring about a reversal of the magnetic induction.
  • FIGS. 4 and 5 The course of the magnetic induction achieved with a system according to FIGS. 4 and 5 is represented beneath FIG. 4 in FIG. 6, in which the curve 6 represents the value of the magnetic field B along the axis 2 of the magnet system. It is recommended that a corresponding magnet system be used if an electron beam is to be guided in bundled form over a very great length, for example up to 20 cm. The necessary magnetic weight is then less than if the guiding is effected with only one reversal field in which, as illustrated in FIG. 3, only two magnetic fields are arranged one behind the other.
  • the permanent magnet systems illustrated in FIGS. 1 and 2 and in FIGS. 4 and 5 are magnetically completely shielded, because the magnetic circuit is closed by the soft iron yokes or bridge members disposed on the side faces.
  • the permanent magnets 1 may consist of a low energy magnetic material with high coercitive strength, for which purpose there is especially suited a hard magnetic ferrite material.
  • a ferrite which has a field strength of 1800 0e. and a magnetic induction of 1800 G. With such a ferrite a maximal magnetic induction is attainable along the system axis of 900 G.
  • the invention is not limited to the examples of construction illustrated.
  • the permanent magnets which are adjacently arranged in closed series can also be of ring-shaped configuration.
  • a permanent magnet system for the generation of at least two magnetic fields, oppositely directed to one another, and lying one behind the other in longitudinal direction of the system, for the bundled guidance of an electron beam over a relatively long path interval, especially for traveling wave tubes, comprising a plurality of permanent magnets arranged symmetrically to the longitudinal axis of the system, said magnets being magnetized perpendicularly with respect to the system axis, soft iron bridge members disposed at the respective poles of the permanent magnets facing away from the system axis magnetically connecting such poles, and soft iron parts disposed at least at the two ends of the system, which in each case form a soft magnetic diaphragm, said permanent magnets being arranged in a closed series, one behind the other between two of said adjacent soft magnetic diaphragms, said permanent magnets being so arranged with respect to the system axis that the magnetic potential of such magnets diminishes from the middle of the closed series toward the two ends thereof, all of the poles of said magnets facing the system axis being of like
  • a permanent magnet system wherein the ends of the permanent magnets facing away from the system axis lie in a common plane, while the ends of the permanent magnets adjacent to the system axis are offset stepwise relative to one another.
  • a permanent magnet system wherein the permanent magnets are arranged, in each case, between two adjacent soft magnetic diaphragms in four closed series which symmetrically surround the system axis.
  • a permanent magnet system according to claim 4 wherein the permanent magnets are arranged, in each case, between two adjacent soft magnetic diaphragms in two closed series opposed to one another and symmetrically disposed relative to the system axis.
  • a permanent magnet system according to claim 1, wherein the permanent magnets are so disposed that the magnetic potential of the respective magnets uniformly decreases from the middle of the closed series toward their two ends in such a way that the magnetic fields lying one behind the other in longitudinal direction of the system are, in each case, homogeneous.
  • a permanent magnet system wherein the permanent magnets, as viewed in longitudinal direction of the system, form two closed series, 'between which there is arranged a soft magnetic diaphragm which extends from the soft iron bridge members perpendicularly toward the system axis.

Landscapes

  • Video Image Reproduction Devices For Color Tv Systems (AREA)
  • Particle Accelerators (AREA)
  • Microwave Tubes (AREA)
US522059A 1965-01-26 1966-01-21 Permanent magnet system for the generation of at least two opposite magnetic fields lying one behind the other for the bundled guidance of an electron beam, especially for traveling wave tubes Expired - Lifetime US3373388A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DES0095153 1965-01-26

Publications (1)

Publication Number Publication Date
US3373388A true US3373388A (en) 1968-03-12

Family

ID=7519172

Family Applications (1)

Application Number Title Priority Date Filing Date
US522059A Expired - Lifetime US3373388A (en) 1965-01-26 1966-01-21 Permanent magnet system for the generation of at least two opposite magnetic fields lying one behind the other for the bundled guidance of an electron beam, especially for traveling wave tubes

Country Status (6)

Country Link
US (1) US3373388A (GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html)
DE (1) DE1491445B2 (GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html)
GB (1) GB1143311A (GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html)
NL (1) NL6517037A (GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html)
NO (1) NO119323B (GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html)
SE (1) SE320734B (GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
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
US5483129A (en) * 1992-07-28 1996-01-09 Mitsubishi Denki Kabushiki Kaisha Synchrotron radiation light-source apparatus and method of manufacturing same
FR2925217A1 (fr) * 2007-12-14 2009-06-19 Thales Sa Structure hyperfrequences pour tube microondes avec dispositif de confinement du faisceau a aimants permanents et refroidissement ameliore

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
US3205415A (en) * 1961-12-27 1965-09-07 Hitachi Ltd Permanent magnet device

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
US3205415A (en) * 1961-12-27 1965-09-07 Hitachi Ltd Permanent magnet device

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5483129A (en) * 1992-07-28 1996-01-09 Mitsubishi Denki Kabushiki Kaisha Synchrotron radiation light-source apparatus and method of manufacturing same
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
FR2925217A1 (fr) * 2007-12-14 2009-06-19 Thales Sa Structure hyperfrequences pour tube microondes avec dispositif de confinement du faisceau a aimants permanents et refroidissement ameliore
WO2009077407A1 (fr) * 2007-12-14 2009-06-25 Thales Structure hyperfrequences pour tube microondes avec dispositif de confinement du faisceau a aimants permanents et refroidissement ameliore
US20100327743A1 (en) * 2007-12-14 2010-12-30 Thales Microwave structure for microwave tube beam confinement device with permanent magnets and enhanced cooling
US8427057B2 (en) 2007-12-14 2013-04-23 Thales Microwave frequency structure for microwave tube with beam-containing device with permanent magnets and enhanced cooling

Also Published As

Publication number Publication date
NO119323B (GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html) 1970-05-04
DE1491445A1 (de) 1969-06-12
NL6517037A (GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html) 1966-07-27
GB1143311A (en) 1969-02-19
SE320734B (GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html) 1970-02-16
DE1491445B2 (de) 1972-04-06

Similar Documents

Publication Publication Date Title
GB995269A (en) Permanent magnet device
US4701737A (en) Leakage-free, linearly varying axial permanent magnet field source
US3227931A (en) Permanent-magnet uniform-field-producing apparatus
US2844754A (en) Electron beam focusing system
GB836219A (en) Improvements in or relating to travelling wave tubes
GB852751A (en) Waveguide circulators
US2871395A (en) Magnetic structures for traveling wave tubes
GB1110172A (en) Improvements in or relating to magnet structures
US2936408A (en) Permanent magnets
US3373388A (en) Permanent magnet system for the generation of at least two opposite magnetic fields lying one behind the other for the bundled guidance of an electron beam, especially for traveling wave tubes
GB726823A (en) Improvements in or relating to magnetic circuits for travelling wave apparatus
US3182234A (en) Permanent magnet system for focusing an electron beam in a travelling wave tube
CA2099813A1 (en) X-z geometry periodic permanent magnet focusing system
US2925517A (en) Electron beam focusing magnetic circuit
US3329915A (en) Permanent magnet system for the bundled guidance of an electron beam over a relatively long path, especially for traveling wave tubes
US3436587A (en) 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
US2579273A (en) Magnetic lens for electron optical systems
US3181042A (en) Permanent magnet system for focusing an electron beam
US4337413A (en) Focusing device with permanent magnets for electron tube and electron tube equipped with such a device
US3133226A (en) Magnetic structure for traveling wave tubes
US4243915A (en) Delay line comprising coupled cavities and cooled by fluid-circulation
US3063027A (en) High power microwave isolator
US2940020A (en) Focusing magnet for long electron beams
GB980119A (en) Periodic magnetic focusing arrangements for electron beam tubes
US3375400A (en) Radial magnet beam focusing system