US3621327A - Method of controlling the intensity of an electron beam - Google Patents

Method of controlling the intensity of an electron beam Download PDF

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Publication number
US3621327A
US3621327A US888279A US3621327DA US3621327A US 3621327 A US3621327 A US 3621327A US 888279 A US888279 A US 888279A US 3621327D A US3621327D A US 3621327DA US 3621327 A US3621327 A US 3621327A
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plane
window
field
axis
electron
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US888279A
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English (en)
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Zia Hashmi
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Fleet National Bank
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Ford Motor Co
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Assigned to ENERGY SCIENCES INC., 8 GILL ST., WOBURN, reassignment ENERGY SCIENCES INC., 8 GILL ST., WOBURN, ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: FORD MOTOR COMPANY
Assigned to FLEET NATIONAL BANK reassignment FLEET NATIONAL BANK ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: ENERGY SCIENCES INC., A CORP. OF NY
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J33/00—Discharge tubes with provision for emergence of electrons or ions from the vessel; Lenard tubes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J29/00—Details of cathode-ray tubes or of electron-beam tubes of the types covered by group H01J31/00
    • H01J29/46—Arrangements of electrodes and associated parts for generating or controlling the ray or beam, e.g. electron-optical arrangement
    • H01J29/52—Arrangements for controlling intensity of ray or beam, e.g. for modulation

Definitions

  • Dennis O'Connor ABSTRACT A method for controlling the cross-sectional area and intensity of an electron beam produced in an electron accelerator.
  • a first constant electric field is applied to the beam causing dispersal of the beam in a first plane and concentration of the beam in a second plane disposed perpendicular to the first plane.
  • a second constant electric field is applied to the beam causing beam concentration in the first plane and beam dispersal in the second plane.
  • the fields are applied to the beam between the origin of the beam and the accelerator window and provide that the cross-sectional area of the beam greatly is enlarged at the point of intersection of the beam and the window relative to its original dimensions.
  • Electron-beam generators or electron accelerators having accelerating voltages in the order of several million volts conventionally include a long insulating container. This container defines an evacuated chamber through which electrons are accelerated to form a beam by means of a large potential difference. existing between an electron gun, including a hot cathode emitter at one end of the chamber, and an anode at the other end of the chamber. The anode includes an electronpenneable window through which the beam passes from the chamber onto a substance being irradiated.
  • beam scanning Another well known procedure for preventing the window overheating due to excessive beam intensity is known as beam scanning. According to this procedure, the beam is scanned over the surface of an elongated window thereby preventing local overheating at any point on the window. It is well-known that beam scanning requires the application of an electric field (either electrostatic or magnetic) that is time varying in order to achieve the desired variance in the beam path.
  • an electric field either electrostatic or magnetic
  • Such scanning methods have certain inherent features that may be undesirable.
  • An appropriate cycle for the varying fields must be established to achieve the desired beam scanning movement.
  • this field cycle must be synchronized with the rate of movement of the target material being irradiated, as such material conventionally is moved continuously past the accelerator window as on a conveyor line to promote maximum utilization of the available radiation energy.
  • the field varying and synchronizing circuits and the hardware necessary for scanning methods are relatively complex, difficult to maintain and subject to break down.
  • this method contemplates defocusing of the beam between its point of origin and the window by applying to the beam unvarying electric fields, the formation of which requires only relatively simple and reliable apparatus. Also, by reducing the intensity of the beam and thus increasing its cross sectional area, this method provides for a larger feasible beam target area.
  • the method of this invention is directed to controlling the cross-sectional area of an electron beam produced in an evacuated container and directed along a straight line toward an electron permeable window in the wall of the container.
  • the method comprises steps of both concentrating the beam in a first plane and dispersing the beam in a second plane at a first location.
  • the first and second planes are perpendicular to one another with the intersection of the planes comprising the straight line along which the beam originally is directed.
  • the beam is dispersed in the first plane and concentrated in the second plane.
  • FIG. 1 is an isometric view illustrating schematically an electron accelerator that may be used to practice the method of this invention
  • FIG. 2 is a schematic representation in a first plane of the beam envelope produced in the accelerator of FIG. 1 and controlled according to the method of this invention
  • FIG. 3 is a view similar to FIG. 2 but illustrating the beam envelope in a second plane that is perpendicular to the first plane of FIG. 2.
  • the numeral 10 denotes generally an accelerator useful in the practice of the method of this invention.
  • This accelerator includes an elongate container 12 defining an internal chamber 14. Proximate one end wall 16 of container 12 is a hot cathode emitter 18. Remote from end wall 16, container 12 includes a tapered portion 20 terminating in an end wall 22. The end wall 22 has formed therethrough an aperture in which is mounted an electron permeable window 24.
  • window 24 is constructed of electronbeam-permeable material such as thin metal foil.
  • the window substantially is square in shape and the window center is the point of intersection of a pair of perpendicular axes designated by the letters X and Y and illustrated to aid in the clarity of this description.
  • Window 24 is mounted in the aperture formed in container end wall 22 such that it provide an airtight seal of this aperture so that a vacuum may be maintained within chamber 14.
  • Window 24 is included in the anode structure of the accelerator. A great potential difference exists between this anode structure and cathode 18 so that electrons emitted by the cathode form an electron beam directed at the window 24.
  • a first pair of coils 26 and 28 are positioned diametrically across the container 12 and may be considered the X-axis coils since they are positioned in the plane containing the X-axis. (The Y-axis intersects and is perpendicular to this plane.)
  • Downstream from coils 26 and 28 are a second pair of coils 30 and 32.
  • Each of the coils 30 and 32 is positioned about the outer periphery of the container from each of the coils 26 and 28.
  • the coils 30 and 32 may be termed the Y-axis coils.
  • Coils 26 and 28 are connected to a suitable source of electrical energy such that these coils give rise to a steady state or unvarying field through that portion of chamber 14 that is located between these coils.
  • coils 30 and 32 are connected electrically to a source of energy such that they give rise to a steady state or unvarying field located therebetween.
  • the manner in which the electric fields created by the coils 26, 28, 30 and 32 are utilized to control the electron beam of the accelerator may be seen by reference to FIGS. 2 and 3 of the drawings.
  • the electron beam envelope is designated by the numeral 34.
  • the direction of travel of the beam is identified by the arrow 36. It may be seen that the beam originates at the cathode 18 as a relatively thin, straight line flow of electrons. The cross sectional area of the beam at this time is quite small since beam diameters of the order of a few millimeters are common. This portion of the beam is designated by the reference numeral 38.
  • the beam downstream from cathode l8, enters the electromagnetic field generated by the X-coils 26 and 28 and represented schematically by the square 40.
  • the portion of the beam within field 40 is identified by the reference numeral 42. From FIG. 2, it may be seen that this field causes a divergence or defocusing of the beam portion 42 in the so-called X-plane, that is, the plane of the drawing of FIG. 2.
  • the X-plane divergence given to the beam portion 42 as it passes through the field 40 continues, of course, after the beam has left the field 40.
  • the portion of the beam immediately downstream from field 40 is identified by the reference numeral 44.
  • the beam portion 42 within field 40 is caused to converge or be focused.
  • a homogeneous steady state electromagnetic field that causes a beam to be defocused in a first plane (the X-plane will simultaneously cause a beam to be focused in a second plane (the Y-plane) that is perpendicular to the first plane. This is the effect that field 40 has upon beam 34.
  • the portion of the beam designated by the numeral 44 that is, that portion of the beam immediately downstream from the field 40, diverges in the X-plane of FIG. 2 since no electric field is acting thereupon.
  • beam portion 44 is converging as it leaves the field 40 as at 440 It thus becomes focused in the Y-plane at a focal point 46.
  • beam portion 44 begins to diverge as at 44b.
  • the electric field caused by the Y-coils 30 and 32 is represented schematically by the square 48 in FIGS. 2 and 3. it may be seen that the portion of the beam passing through this field is designated by the numeral 50.
  • beam portion 50 is acted upon by field 48 and the divergence that continues along beam portion 44 is arrested and a slight convergence of the beam at beam portion 50 occurs.
  • This action of field 48 prevents too great a lessening of the beam intensity and creates a controlled X-plane dimension and beam intensity at the window 24. It may be seen that this slight convergence caused by field 48 continues downstream of the field 48 whereat the beam portion is designated by the numeral 52.
  • the slight beam divergence of beam portion 44b is increased in beam portion 50. This divergence continues of course downstream of field 48 along beam portion 52 until the beam intersects the window 24.
  • the beam dimensions along the X- and Y-axes approximately are the same and that these dimensions are much greater than corresponding dimensions of the beam prior to the entry of the beam into the fields created by the electromagnetic coils. Since the beam cross-sectional area at the window is much greater than at the point or origin, the beam intensity at the window accordingly is decreased relative to its original intensity. The beam thus constantly may be applied to window 24 without the danger of overheating.
  • the extent to which a particular electron beam is defocused and its intensity is decreased is dependent of course, on the particular apparatus involved and easily may be determined empirically. it thus may be seen that the method of this invention allows an electron beam to be controlled so that there is no need for scanning of the beam along the accelerator window or for operation of the accelerator at less than full capacity.
  • a method for effecting the efiicient distribution of available ionizing energy from an electron beam produced in an evacuated container and directed along a first axis toward an electron-permeable window in a wall of said container comprising the steps of: app] ing a first field to said beam, said field causing said beam to concentrated along a second axis that is perpendicular to said first axis and dispersed along a third axis that is perpendicular to both said first and second axes, and applying a second field to said beam, said second field being spaced along said first axis from said first field, causing said beam to be dispersed along said second axis and concentrated along said third axis.
  • a method for controlling the cross-sectional area of an electron beam produced in an evacuated container and directed along a straight line toward an electron permeable window in a wall of said container comprising the steps of: at a first location concentrating said beam in a first plane and dispersing said beam in a second plane, said first and second planes being perpendicular to one another and the intersection of said planes comprising said straight line, and at a second location between said first location and said window dispersing said beam in said first plane and concentrating said beam in said second plane, whereby the crosssectional area of said beam is greater at said window than at the point of origin of said beam.

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  • Particle Accelerators (AREA)
  • Recrystallisation Techniques (AREA)
US888279A 1969-12-29 1969-12-29 Method of controlling the intensity of an electron beam Expired - Lifetime US3621327A (en)

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US88827969A 1969-12-29 1969-12-29

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BE (1) BE760883A (enrdf_load_html_response)
DE (1) DE2064273A1 (enrdf_load_html_response)
FR (1) FR2073802A5 (enrdf_load_html_response)
GB (1) GB1292178A (enrdf_load_html_response)
NL (1) NL7018963A (enrdf_load_html_response)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3845312A (en) * 1972-07-13 1974-10-29 Texas Instruments Inc Particle accelerator producing a uniformly expanded particle beam of uniform cross-sectioned density
US4002912A (en) * 1975-12-30 1977-01-11 The United States Of America As Represented By The United States Energy Research And Development Administration Electrostatic lens to focus an ion beam to uniform density
US4293772A (en) * 1980-03-31 1981-10-06 Siemens Medical Laboratories, Inc. Wobbling device for a charged particle accelerator
US4804851A (en) * 1984-06-19 1989-02-14 Texas Instruments Incorporated Charged particle sources
US4958078A (en) * 1989-01-05 1990-09-18 The University Of Michigan Large aperture ion-optical lens system
US20080073549A1 (en) * 2006-02-14 2008-03-27 Tzvi Avnery Electron beam emitter
EP2325089B1 (de) * 2007-04-19 2016-12-21 Krones AG Vorrichtung zum Sterilisieren von Behältnissen

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FI84961C (fi) * 1989-02-02 1992-02-10 Tampella Oy Ab Foerfarande foer alstrande av hoegeffektelektronridaoer med hoeg verkningsgrad.

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2680815A (en) * 1950-12-28 1954-06-08 High Voltage Engineering Corp Method of and apparatus for treating substances with high energy electrons
US2866902A (en) * 1955-07-05 1958-12-30 High Voltage Engineering Corp Method of and apparatus for irradiating matter with high energy electrons
US3028491A (en) * 1958-06-20 1962-04-03 Zeiss Carl Apparatus for producing and shaping a beam of charged particles
US3270243A (en) * 1961-03-21 1966-08-30 Gen Dynamics Corp Apparatus for the establishment and acceleration of a narrow high current beam

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2680815A (en) * 1950-12-28 1954-06-08 High Voltage Engineering Corp Method of and apparatus for treating substances with high energy electrons
US2866902A (en) * 1955-07-05 1958-12-30 High Voltage Engineering Corp Method of and apparatus for irradiating matter with high energy electrons
US3028491A (en) * 1958-06-20 1962-04-03 Zeiss Carl Apparatus for producing and shaping a beam of charged particles
US3270243A (en) * 1961-03-21 1966-08-30 Gen Dynamics Corp Apparatus for the establishment and acceleration of a narrow high current beam

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3845312A (en) * 1972-07-13 1974-10-29 Texas Instruments Inc Particle accelerator producing a uniformly expanded particle beam of uniform cross-sectioned density
US4002912A (en) * 1975-12-30 1977-01-11 The United States Of America As Represented By The United States Energy Research And Development Administration Electrostatic lens to focus an ion beam to uniform density
US4293772A (en) * 1980-03-31 1981-10-06 Siemens Medical Laboratories, Inc. Wobbling device for a charged particle accelerator
EP0037051B1 (de) * 1980-03-31 1985-01-23 Siemens Aktiengesellschaft Linearbeschleuniger für geladene Teilchen
US4804851A (en) * 1984-06-19 1989-02-14 Texas Instruments Incorporated Charged particle sources
US4958078A (en) * 1989-01-05 1990-09-18 The University Of Michigan Large aperture ion-optical lens system
US20080073549A1 (en) * 2006-02-14 2008-03-27 Tzvi Avnery Electron beam emitter
US7759661B2 (en) 2006-02-14 2010-07-20 Advanced Electron Beams, Inc. Electron beam emitter for sterilizing containers
US20100247373A1 (en) * 2006-02-14 2010-09-30 Advanced Electron Beams, Inc. Electron beam emitter for sterilizing containers
US8258486B2 (en) 2006-02-14 2012-09-04 Hitachi Zosen Corporation Electron beam emitter for sterilizing containers
US8586944B2 (en) 2006-02-14 2013-11-19 Hitachi Zosen Corporation Electron beam emitter for sterilizing containers
EP2325089B1 (de) * 2007-04-19 2016-12-21 Krones AG Vorrichtung zum Sterilisieren von Behältnissen

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DE2064273A1 (de) 1971-07-08
BE760883A (enrdf_load_html_response) 1971-05-27
NL7018963A (enrdf_load_html_response) 1971-07-01
FR2073802A5 (enrdf_load_html_response) 1971-10-01
GB1292178A (en) 1972-10-11

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Owner name: ENERGY SCIENCES INC., 8 GILL ST., WOBURN, MA

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