US3660658A - Electron beam deflector system - Google Patents

Electron beam deflector system Download PDF

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Publication number
US3660658A
US3660658A US16529A US3660658DA US3660658A US 3660658 A US3660658 A US 3660658A US 16529 A US16529 A US 16529A US 3660658D A US3660658D A US 3660658DA US 3660658 A US3660658 A US 3660658A
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United States
Prior art keywords
deflector system
electromagnet
deflecting
plane
deflector
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Expired - Lifetime
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US16529A
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English (en)
Inventor
Hubert Leboutet
Jean Jaouen
Jeanne Aucouturier
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Thales SA
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Thomson CSF SA
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    • G—PHYSICS
    • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
    • G21K—TECHNIQUES FOR HANDLING PARTICLES OR IONISING RADIATION NOT OTHERWISE PROVIDED FOR; IRRADIATION DEVICES; GAMMA RAY OR X-RAY MICROSCOPES
    • G21K1/00—Arrangements for handling particles or ionising radiation, e.g. focusing or moderating
    • G21K1/08—Deviation, concentration or focusing of the beam by electric or magnetic means
    • G21K1/093—Deviation, concentration or focusing of the beam by electric or magnetic means by magnetic means

Definitions

  • the apparatus concerned generally comprise electron accelerator devices, and devices, generally of a magnetic nature, for guiding and deflecting accelerated electrons.
  • the angle of incidence of the electron beam upon the object being irradiated or bombarded should be readily varied, and therefore the radiography or radiotherapy machine has to rotate around the object. Due to the dimensions and weight of electron accelerators, bulky and expensive mountings have thus to be provided.
  • an arrangement for deflecting the electron beam of a particle accelerator comprising a first and a second deflector system, said first deflector system comprising means for deflecting said beam through a first predetermined angle in a given plane, and said second deflector system comprising means for deflecting said beam through a second angle in said given plane so predetermined that the final direction of said beam intersects the initial direction thereof.
  • FIG. 1 illustrates an overall diagram of the system according to the invention
  • FIG. 2 illustrates a detailed view of one of the electromagnets belonging to a first part of the magnetic deflection system
  • FIG. 3 illustrates a detailed view of a variant embodiment of one of the above electromagnets
  • FIGS. 4a and 4! illustrate an electromagnet belonging to a second part of the magnetic deflection system
  • FIG. 5 illustrates a modified embodiment of the electromagnet shown in FIGS. 4a and 4b
  • FIGS. 6a, 6band 6c illustrate a detailed section through an electromagnet belonging to the second part of the magnetic deflection system, in accordance with a second embodiment.
  • FIG. 7 illustrates a magnetic deflection system for imposing an angular scan motion on the beam, as a function of time
  • FIG. 8 illustrates a magnetic deflection system for producing a second type of angular scan as a function of time.
  • FIG. 1 a schematic overall view of the pivoting device in accordance with the invention, has been given, and in order to simplify description, this system will be referred to in the ensuing text as a rotary deflection system.
  • first deflection under the action of a first set of electromagnets D which deflect it through an angle a in the clockwise direction in a plane containing the axis XX
  • second deflection under the action of a second system of electromagnets D which deflect it in the reverse direction, in the same plane, through an angle [3 such that the direction of the beam at the exit from the second system makes an angle of substantially 90 with that which it has at the input of the first electromagnet system, and consequently with the axis XX, the displacement being in the direction of this axis.
  • the angle a can be, for example, of 37 and the angle B of 127.
  • the plane in which the directions of the two deflections are contained is a plane of symmetry for the rotary deflection system and the electron beam, and, in order to simplify the ensuing description, will be referred to in the following as the plane of the figure.
  • FIG. 2 shows in perspective one of the three deflection electromagnets, of the assembly D
  • the magnetic circuit comprises a yoke 3 connecting the two pole-pieces 4, which take the form of sectors, and only one of which has been illustrated for the sake of clarity, and two magnetic coils 5.
  • These three electromagnets which create magnetic fields in a direction perpendicular to the plane of the figure, are arranged successively in the path of the electron beam so that the intermediate electromagnet is head-to-tail with the first and third ones, and so that the direction of its magnetic field is opposite to that of the outside electromagnets, thus producing electron trajectories which alternately curve in one direction and then the other.
  • This device has been improved in the present Application in that, in order to compensate for the divergence of the electron beam, the latter has been made convergent, in the electronoptical sense, in the two directions corresponding respectively to the plane of the Figure and to the direction perpendicular to the plane of the Figure.
  • this angle can be adjusted by giving the terminal faces of the corresponding pole-pieces, the form of cylinders 6, rotatably mounted on axes perpendicular to the plane defined by the trajectories of the beam.
  • the supply of electric current to the three electromagnets of the deflection device D can be effected in series, so that the magnetization of the system can be regulated in an overall fashion moreover, individual secondary windings can be used to adjust the strength of the magnetic field created by the main current.
  • the second electromagnet is located substantially at the horizontal object focus of the exit electromagnet, as described in the patent referred to hereinbefore, when the current through said second electromagnet is varied the exit beam will be displaced in the plane of the figure, parallel to itself similarly, if the current in the third electromagnet is varied, the beam will pivot, in the plane of the figure, substantially about the center of the third electromagnet.
  • FIG. 4 a detailed illustration has been given of the structure and disposition of the electromagnets which make up the electromagnet system D
  • This system is formed by a single deflector electromagnet E however, in accordance with a modification, it may be followed by a complementary system of magnetic lenses.
  • the respective characteristics and modes of operation are described.
  • the purpose of the electromagnet is to deflect the electron beam as indicated hereinbefore, and the way in which it operates is quite obvious however, in a preferred embodiment, it can be given a secondary function, namely that of an optically convergent element.
  • the polepieces will be given a generally frusto-conical form, so that the electromagnet air-gap varies as a function of the distance from the center of curvature of the electromagnet.
  • the magnetic field thus produced consequently exhibits a gradient and a particular value of this gradient is advantageous.
  • n index equal to +0.5, this index here having the usual meaning, and being defined by where B is the magnetic flux in the electromagnet gap corresponding to the radius R of the particle trajectories.
  • the preferred index n of +0.5 gives the electromagnet identical convergence properties in the plane of the figure and in the plane perpendicular thereto.
  • the entry and exit faces of the electromagnet E exhibit the following advantageous features
  • the entry face 7 is not perpendicular to the beam but inclined in relation thereto in such a fashion that it produces convergence in the plane of the figure any electron of the beam differing from the mean electron either by its energy or by a transverse distance therefrom, and arriving at said face parallel to the general axis of the beam and in the plane of the figure will thus appear, when it reaches the exit face, to have emanated from a point source F.
  • this source will be situated at about 1.4 times the radius of curvature of the beam trajectory, on the straight line projecting the exit axis.
  • the exit face 8 likewise has an inclination to the plane normal to the beam in order to produce a convergent effect in the plane of the Figure, similar to the effect obtained by inclination of the entry face.
  • the angle at the exit face is not critical and the convergence produced there is essentially designed to counteract the natural divergence of the beam emanating from the virtual source F, and this result will be achieved if the angle of the exit face is 35, for which value the system, in the optical sense, is afocal and has a magnification of l in a plane perpendicular to the plane of the figure.
  • the angle of the exit face can be increased up to 45 at the expense of a slight divergence in the system in the plane perpendicular to that of the figure.
  • the convergence can be adjusted by utilizing rotational electromagnet entry and exit faces, as described hereinbefore.
  • the beam will thus have convergence in the plane of the figure and divergence in the plane perpendicular thereto, this leading to an elliptical section beam with the major axis perpendicular to the plane of the figure.
  • the electromagnet E does not ensure passage at the same point, i.e focusing, of the electrons of different velocities, and spreads their trajectories in the plane of the figure the nett result is an elliptical section the major axis of which is contained in the plane ofthe figure.
  • FIG. illustrates a variant embodiment which will be described hereinafter and which comprises, in addition to the electromagnet E.,, a magnetic device which will enable the above end to be achieved.
  • This embodiment comprises, beyond the exit fact of the electromagnet E.,, as illustrated in FIG. 3, a system of three quadripolar magnetic lenses forming a symmetrical triplet located in the path of the beam.
  • Systems of this kind are vwell known in the art and those skilled in the art will appreciate that by varying different parameters, such as the currents involved or certain dimensions such as the axial length of the poles, it is possible to vary the magneto-optical characteristics of a triplet separately in the two principal mutually perpendicular planes, i.e. the plane of the figure and the plane perpendicular thereto.
  • the triplet considered is made up of three quadrupolar magnetic lenses located in the path of the beam.
  • his kind of lens has properties of convergence in the particular plane passing through its optical axis, and of divergence in a plane perpendicular to the first and passing likewise through the optical axis.
  • the preferred order of the three quadripolar magnetic lenses making up the triplet is contrived so that, in the plane of the figure, they are successively and respectively convergent, divergent and convergent.
  • FIG. 6 illustrates a variant embodiment in which the air-gap of the electromagnet E is divided into two parts trough which the beam successively passes.
  • the first part 25 has the form of pole-pieces which create a field gradient of index n +0.5 as explained already hereinbefore in the second part 26, the field gradient, on the contrary, is negative and the index is high, 2 or 3 for example.
  • the entry face 27 is normal to the beam, while the exit face 28 on the other hand makes a substantial angle with the plane normal to the beam the angle is variable in order to enable the convergence to be regulated, this by employing a rotary cylindrical component 21 similar to those already described in relation to FIG. 3.
  • a final set of characteristic features of the present invention is intended to achieve a geometric scanning of the irradiation zone along two mutually perpendicular cartesian coordinates, by the point of impact of the electron beam, or of the X-ray beam produced by the bombardment of an appropriate metal target. This allows a much larger area than that defined by the beam section alone to be bombarded.
  • FIG. 7 illustrates in the case of an electron beam, an arrangement which will enable the desired result to be achieved.
  • a quadripolar electromagnet is arranged comprising coils 12 and pole-pieces 13 extending through the coils and magnetized by same so that the beam is deflected in two perpendicular directions and can thus reach any point on the area to be scanned.
  • the preferred location of the quadripole device is such that its center of deflection coincides with the image focus of the triplet beyond which it is situated, and the preferred form of the polepieces is one in which the air-gap faces 14 are inclined so that a conical taper is formed to permit the free inclination of the trajectories without any interception of the electrons.
  • FIG. 8 relates to the X-ray scanning.
  • the advantage of this kind of scanning resides in the possibility of obtaining uniform irradiation over an extensive area; if, in order to equalize the radiation, recourse is had to the conventional solution employing an equalizer disc of variable thickness operating by absorption of part of the radiation, then it is possible to give this disc smaller variations in thickness. Consequently, its construction is simplified and a smaller fraction of the radiation is absorbed therely.
  • This result can be obtained by a purely magnetic arrangement.
  • One very simple embodiment consists in exploiting the specific deflecting characteristics of the electromagnet E,. Depending upon the magnitude of the current used to supply it, this electromagnet produces differential deflection of the electrons which leave its exit face at different points for a field which is stronger than a field corresponding to exit along the mean axis, the electrons are deflected further and exit at 20 for a weaker field, they are not deflected so much and exit at 21.
  • the variation in magnetic field in E is simple to obtain by modulation of the magnetizing current.
  • an additional winding through which an electric current, variable in magnitude and sign, flows.
  • the total angular amplitude in the plane of the figure is in the order of 3 for an amplitude of 1 percent on the part of the modulation of the magnetic field.
  • the period of the oscillations is in the order of a fraction of a second.
  • geometric scanning is likewise obtainable by arranging, for example at the exit from the triplet system D, an electromagnet 24 which produces in the plane of the figure a magnetic field which is variable in time, in magnitude and sign.
  • An arrangement for deflecting the electron beam of a particle accelerator which comprises in combination, a mounting pivotally mounted at the accelerator exit for rotation about the axis of the beam, said mounting securing a first and a second deflector system, said first deflector system having means for deflecting said beam through a first predetermined angle in a given plane, and said second deflector system having means for deflecting said beam through a second angle in said given plane so predetermined that the final direction of said beam intersects the initial direction thereof at an angle at least equal to said first deflector system having means for deflecting said beam and comprising three electromagnets forming an achromatic system, the respective entry and exit faces of the pole-pieces of said electromagnets making angles different from zero with planes perpendicular to the axis of said beam whereby said deflector system is made convergent, said second deflector system comprising an electromagnet having pole pieces whose entry and exit faces respectively make angles other than zero with planes perpendicular to the beam axis
  • pole-pieces of the electromagnet of the second deflector system have an air-gap, in a first part of which air-gap the width is at any point thereof proportional to its distance to the curvature center of the mean beam path and said distance.
  • entry and exit faces of said second deflector system carry plates of ferromagnetic material pivotally mounted about an axis parallel to the magnetic field, whereby said angles are adjustable.

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  • Physics & Mathematics (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • High Energy & Nuclear Physics (AREA)
  • Particle Accelerators (AREA)
  • Radiation-Therapy Devices (AREA)
  • Analysing Materials By The Use Of Radiation (AREA)
  • Apparatus For Radiation Diagnosis (AREA)
US16529A 1969-03-12 1970-03-04 Electron beam deflector system Expired - Lifetime US3660658A (en)

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FR6906976A FR2036373A5 (de) 1969-03-12 1969-03-12

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US (1) US3660658A (de)
JP (1) JPS5531440B1 (de)
BE (1) BE747049A (de)
CH (1) CH514341A (de)
FR (1) FR2036373A5 (de)
GB (1) GB1269017A (de)
NL (1) NL172103C (de)

Cited By (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4056728A (en) * 1972-01-31 1977-11-01 C.G.R.-Mev. Magnetic deflecting and focusing device for a charged particle beam
US4122346A (en) * 1977-03-23 1978-10-24 High Voltage Engineering Corporation Optical devices for computed transaxial tomography
EP0041753A2 (de) * 1980-06-10 1981-12-16 Philips Electronics Uk Limited Einrichtung zum Ablenken von Ladungsträgern
US4442352A (en) * 1979-05-17 1984-04-10 Instrument Ab Scanditronix Scanning system for charged and neutral particle beams
US4588955A (en) * 1983-06-01 1986-05-13 The United States Of America As Represented By The United States Department Of Energy Transverse field focused system
US6040566A (en) * 1997-01-31 2000-03-21 Thomson-Csf Device to control the aiming and focusing of laser systems on a target
US6522056B1 (en) 1999-07-02 2003-02-18 Coincident Beams Licensing Corporation Method and apparatus for simultaneously depositing and observing materials on a target
US6696688B2 (en) 2000-09-07 2004-02-24 Diamond Semiconductor Group, Llc Apparatus for magnetically scanning and/or switching a charged-particle beam
US20040036031A1 (en) * 2001-02-20 2004-02-26 Harald Rose Particle beam system having a mirror corrector
US20040075053A1 (en) * 2001-02-20 2004-04-22 Leo Elektronenmikroskopie Gmbh Particle-optical arrangements and particle-optical systems
US20110224475A1 (en) * 2010-02-12 2011-09-15 Andries Nicolaas Schreuder Robotic mobile anesthesia system
US8183526B1 (en) * 2011-02-11 2012-05-22 Electron Optica Mirror monochromator for charged particle beam apparatus
US20160314929A1 (en) * 2015-04-23 2016-10-27 Cryoelectra Gmbh Beam Guidance System, Particle Beam Therapy System and Method
CN113409981A (zh) * 2021-06-18 2021-09-17 中国科学院近代物理研究所 一种用于电子束辐照加工的多面辐照方法及系统

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS6227735U (de) * 1985-08-01 1987-02-19
JPS62295347A (ja) * 1986-04-09 1987-12-22 イクリプス・イオン・テクノロジ−・インコ−ポレイテツド イオンビ−ム高速平行走査装置
US4745281A (en) * 1986-08-25 1988-05-17 Eclipse Ion Technology, Inc. Ion beam fast parallel scanning having dipole magnetic lens with nonuniform field

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US2602751A (en) * 1950-08-17 1952-07-08 High Voltage Engineering Corp Method for sterilizing substances or materials such as food and drugs
US2777958A (en) * 1951-02-10 1957-01-15 Hartford Nat Bank & Trust Co Magnetic electron lens
US2932738A (en) * 1955-09-15 1960-04-12 Commissariat Energie Atomique Magnetic prisms for separating ionized particles
US2999185A (en) * 1950-01-09 1961-09-05 Harry R Lubcke Television device
US3031596A (en) * 1958-03-13 1962-04-24 Csf Device for separating electrons in accordance with their energy levels
US3287558A (en) * 1961-09-08 1966-11-22 High Voltage Engineering Corp Charged particle deflecting device consisting of sequentially positioned uniform and non-uniform magnetic field sectors
US3331978A (en) * 1962-05-28 1967-07-18 Varian Associates Electron beam x-ray generator with movable, fluid-cooled target
US3358239A (en) * 1965-07-27 1967-12-12 Transformatoren & Roentgenwerk Equipment for controlling and monitoring the electron beam of a horizontaltype particle accelerator
US3360647A (en) * 1964-09-14 1967-12-26 Varian Associates Electron accelerator with specific deflecting magnet structure and x-ray target

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2999185A (en) * 1950-01-09 1961-09-05 Harry R Lubcke Television device
US2602751A (en) * 1950-08-17 1952-07-08 High Voltage Engineering Corp Method for sterilizing substances or materials such as food and drugs
US2777958A (en) * 1951-02-10 1957-01-15 Hartford Nat Bank & Trust Co Magnetic electron lens
US2932738A (en) * 1955-09-15 1960-04-12 Commissariat Energie Atomique Magnetic prisms for separating ionized particles
US3031596A (en) * 1958-03-13 1962-04-24 Csf Device for separating electrons in accordance with their energy levels
US3287558A (en) * 1961-09-08 1966-11-22 High Voltage Engineering Corp Charged particle deflecting device consisting of sequentially positioned uniform and non-uniform magnetic field sectors
US3331978A (en) * 1962-05-28 1967-07-18 Varian Associates Electron beam x-ray generator with movable, fluid-cooled target
US3360647A (en) * 1964-09-14 1967-12-26 Varian Associates Electron accelerator with specific deflecting magnet structure and x-ray target
US3358239A (en) * 1965-07-27 1967-12-12 Transformatoren & Roentgenwerk Equipment for controlling and monitoring the electron beam of a horizontaltype particle accelerator

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Title
Experimental Evaluation of the Physical Characteristics of a 45 MEV Medical Linear Electron Accelerator by C. L. Hsieh et al. from Radiology, Vol. 67, No. 2, Aug. 1956, pp. 263 272. *

Cited By (24)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4056728A (en) * 1972-01-31 1977-11-01 C.G.R.-Mev. Magnetic deflecting and focusing device for a charged particle beam
US4122346A (en) * 1977-03-23 1978-10-24 High Voltage Engineering Corporation Optical devices for computed transaxial tomography
US4442352A (en) * 1979-05-17 1984-04-10 Instrument Ab Scanditronix Scanning system for charged and neutral particle beams
EP0041753A2 (de) * 1980-06-10 1981-12-16 Philips Electronics Uk Limited Einrichtung zum Ablenken von Ladungsträgern
EP0041753A3 (en) * 1980-06-10 1983-09-28 Philips Electronic And Associated Industries Limited Deflection system for charged-particle beam
US4588955A (en) * 1983-06-01 1986-05-13 The United States Of America As Represented By The United States Department Of Energy Transverse field focused system
US6040566A (en) * 1997-01-31 2000-03-21 Thomson-Csf Device to control the aiming and focusing of laser systems on a target
US20040207308A1 (en) * 1999-07-02 2004-10-21 Michael Mauck Method and apparatus for simultaneously depositing and observing materials on a target
US20050161616A1 (en) * 1999-07-02 2005-07-28 Microtrue Machine Tool Corporation Method and apparatus for simultaneously depositing and observing materials on a target
US20080258073A1 (en) * 1999-07-02 2008-10-23 Coincident Beams Licensing Corporation Method and apparatus for simultaneously depositing and observing materials on a target
US7078852B2 (en) 1999-07-02 2006-07-18 Coincident Beams Licensing Corporation Method and apparatus for simultaneously depositing and observing materials on a target
US6611087B2 (en) 1999-07-02 2003-08-26 Coincident Beams Licensing Corporation Method and apparatus for simultaneously depositing and observing materials on a target
US6522056B1 (en) 1999-07-02 2003-02-18 Coincident Beams Licensing Corporation Method and apparatus for simultaneously depositing and observing materials on a target
US6815880B2 (en) 1999-07-02 2004-11-09 Coincident Beams Licensing Corporation Method and apparatus for simultaneously depositing and observing materials on a target
US6906453B2 (en) 1999-07-02 2005-06-14 Coincident Beams Licensing Corporation Method and apparatus for simultaneously depositing and observing materials on a target
US6696688B2 (en) 2000-09-07 2004-02-24 Diamond Semiconductor Group, Llc Apparatus for magnetically scanning and/or switching a charged-particle beam
US6855939B2 (en) * 2001-02-20 2005-02-15 Leo Elektronenmikroskopie Gmbh Particle beam system having a mirror corrector
US20040075053A1 (en) * 2001-02-20 2004-04-22 Leo Elektronenmikroskopie Gmbh Particle-optical arrangements and particle-optical systems
US7022987B2 (en) 2001-02-20 2006-04-04 Carl Zeiss Nis Gmbh Particle-optical arrangements and particle-optical systems
US20040036031A1 (en) * 2001-02-20 2004-02-26 Harald Rose Particle beam system having a mirror corrector
US20110224475A1 (en) * 2010-02-12 2011-09-15 Andries Nicolaas Schreuder Robotic mobile anesthesia system
US8183526B1 (en) * 2011-02-11 2012-05-22 Electron Optica Mirror monochromator for charged particle beam apparatus
US20160314929A1 (en) * 2015-04-23 2016-10-27 Cryoelectra Gmbh Beam Guidance System, Particle Beam Therapy System and Method
CN113409981A (zh) * 2021-06-18 2021-09-17 中国科学院近代物理研究所 一种用于电子束辐照加工的多面辐照方法及系统

Also Published As

Publication number Publication date
NL172103C (nl) 1983-07-01
JPS5531440B1 (de) 1980-08-18
CH514341A (fr) 1971-10-31
DE2011385B2 (de) 1977-07-07
BE747049A (fr) 1970-08-17
FR2036373A5 (de) 1970-12-24
GB1269017A (en) 1972-03-29
DE2011385A1 (de) 1970-09-17
NL7003447A (de) 1970-09-15

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