US3679930A - Method for increasing the output of an electron accelerator - Google Patents

Method for increasing the output of an electron accelerator Download PDF

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Publication number
US3679930A
US3679930A US849705A US3679930DA US3679930A US 3679930 A US3679930 A US 3679930A US 849705 A US849705 A US 849705A US 3679930D A US3679930D A US 3679930DA US 3679930 A US3679930 A US 3679930A
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Prior art keywords
scanning
coils
window
windows
pair
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US849705A
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English (en)
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Alex D Colvin
David H Mcnitt
Allen H Turner
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Ford Motor Co
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Ford Motor Co
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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

Definitions

  • 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 electron permeable window through which the beam passes from the chamber onto a substance being irradiated.
  • Cooling means such as blasts of air directed along the window are being used, but they are not sufficient in themselves to dissipate enough heat to prevent adverse heating effects. Also, it has been proposed to prevent excessive localized heating by increasing greatly the size of the window so that the beam may be scanned over a large area.
  • beam aperture windows also limits the efiectiveness of various multi-dimension beam scanning methods designed to prevent overheating. Such methods do not restrict beam movement to a single dimension, that is, along the length of the window, but rather provide for additional beam scanning at least along the transverse dimension of the window. Narrow window shapes greatly impede beam movement back and forth along the length of the window, regardless of transverse beam manipulations, without subsequent heating of already heated locales and the consequent danger of overheating.
  • This method takes advantage of a relatively large window area that is a composite of plural windows, and provides for beam scanning over the entire composite area without undue wastage of beam current due to impingement of the beam on impermeable structure.
  • This invention provides a method for increasing the output of an electron accelerator by effecting this efiicient distribution of available ionizing energy from the electron beam produced in the evacuated container of the accelerator and directed toward at least a pair of elongate, electron permeable windows arranged in a side-by-side, spaced apart configuration in the wall of the container.
  • This method includes scanning the beam over a predetermined time period along the length of a first of the windows and then instantaneously directing the beam from the first window to the second of the windows.
  • the beam then is scanned over a predetermined time period along the length of the second of the windows and then instantaneously directed from the second window to the first window.
  • the beam scanning along the length of the first window is in a direction 180 from the direction of the beam scanning along the length of theother window.
  • FIG. I is an isometric view illustrating schematically 'an electron accelerator that may be used to practice the method of this invention.
  • FIG. 2 is a view taken along the line of sight identified by the arrow 2 in FIG. 1;
  • FIG. 3 is a schematic representation of circuitry utilized in conjunction with theaccelerator of FIG. 1 and;
  • FIG. 4 is a composite representation of six electrical signals generated by the circuitry of FIG. 3, these signals being plotted against time.
  • 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 I2 is a hot cathode emitter 18.
  • container 12 Remote from end wall 16, container 12 includes a tapered portion 20 terminating in an end wall 22.
  • End wall 22 has formed therethrough a pair of elongated apertures in which are mounted electron permeable, spaced apart window members 24 and 26v
  • window members 26 may be constructed of such electron beam permeable material as thin metal foil.
  • the window members are substantially rectangular and are spaced apart with their longitudinal axes lying substantially parallel to one another.
  • Windows 24 and 26 are mounted in the apertures formed in the container end wall 22 such that they provide an air tight seal of these apertures so that a vacuum may be maintained within chamber 14.
  • Windows 24 and 26 are included in the anode structure of the accelerator. A great potential difference exists between this anode structure and cathode 18 such that electrons emitted by the cathode form an electron beam directed at the windows 24 and 26.
  • Control of the direction of this electron beam is provided by four electromagnetic scanning coils 28, 30, 32 and 34 positioned 90 apart about the outer periphery of the container 12.
  • coils 28 and 30 are positioned to scan an electron beam emitted by cathode 18 in directions parallel to the Y-axis shown in FIG. 2, that is, parallel to the longitudinal axes of windows 24 and 26.
  • Coils 32 and 34 are positioned to scan the electron beam parallel to the X-axis shown in FIG. 2, that is, transverse to the longitudinal axes of the windows 24 and 26.
  • the scanning coils 28, 30, 32 and 34 have the current passing therethrough and the resultant magnetic field produced varied such that the electron beam extending the length of chamber 14 has its direction varied in a particular manner.
  • the particular scanning pattern that results provides that the current intensity of the beam is maximized without danger of overheating of the windows 24 and 26.
  • the manner in which the electron beam is controlled may be appreciated by reference to H6. 2. Let it be assumed that the electron beam initially is directed by the scanning coils such that it impinges upon window 26 at point 36. This point 36 is chosen arbitrarily as the scanning of the electron beam in a closed path as explained below is a continuous operation such that any point along the closed path may be considered a starting or finishing point.
  • the current passing through scanning coils 32 and 34 is maintained at a constant level such that no transverse movement parallel to the X-axis of the beam occurs.
  • the current passing through coils 28 and 30 is varied such that the beam is canned over a predetermined period of time along the broken line 38 as indicated by the arrows on the line.
  • the current passing through coils 32 and 34 instantaneously is varied to a second constant level.
  • This instantaneous variance produces an instantaneous movement of the beam along the straight line 40 in a direction parallel to the X- axis.
  • This instantaneous movement of the beam from window 26 to window 24 precludes the wastage of'beam energy due to impingement of the beam on the portion of end wall 22 located between windows 24 and 26.
  • the current in beams 28 and 30 is varied such that the beam is scanned over a predetermined period of time along the length of window 24 as indicated by the broken line 42 and in a direction indicated by the arrows on line 42.
  • the direction in which the beam is scanned along the window 24 is 180 from the direction along which the beam is scanned over the window 26.
  • an instantaneous variance in the current passing through coils 32 and 34 causes an instantaneous movement of the beam along the line 44 such that the beam is directed from window 24 to window 26 and the starting point of the scanning cycle point 36.
  • this movement from window 24 to window 26 occurs instantaneously and thus prevents the wastage of beam energy.
  • a pulse generator 46 is connected electrically by means of a signal transmitting means 48 to a square wave generator 50 that sends output signals along a pair of signal transmitting means 52 and 54 to a Y-axis driver 56 that in turn emits along signal transmitting means 58 the final current signal that is directed to coils 28 and 30.
  • the current in these coils determines beam movement along the Y-axis.
  • the signal transmitted to the Y driver 56 along signal transmitting means 52 and 54 also is transmitted along signal transmitting means 60 and 62, respectively, to the X driver 54 that produces current signals that are directed to coils 32 and 34 by means of signal transmitting means 66 and 68, respectively.
  • the X driver is so termed because coils 32 and 34 determine beam scanning movement parallel to the X axis of FIG. 2.
  • thepulse generator 46, square wave generator 50, Y driver 56 and X driver 64 are conventional electrical circuits that quite easily may be constructed by one having ordinary skill in the art.
  • the signal transmitting means 48, 52, 54, 58, 60, 62, 66 and 68 may be such conventional electrical components as conductive wire leads and thus constitute no part of the instant invention.
  • plot 4a represents the voltage signal emitted by pulse generator 46 along signal transmitting means 48 to square wave generator 50. It may be seen that this signal is merely a periodic pulse having a constant frequency.
  • the output signal voltage of the square wave generator 50 along the signal transmitting means 52 and 54 are represented by the plots 4b and 4c, respectively. It may be seen that plots 4b and 4c comprise square wave 180 out of phase and having a frequency the same as the frequency of the pulses of plot 40.
  • Plot M represents the saw toothed current signal emitted by the Y driver 56 that receives voltage signals 4b and 4c.
  • Current wave 4d is directed to both coils 28 and 30. that are connected in parallel, via the signal transmitting means 58.
  • magnetic fields given off by coils 28 and 30 caused the electron beam produced in the accelerator 10 to be scanned in a first direction along the length of one of the windows 24 or 26.
  • the electron beam is scanned in a second direction, opposite to the first direction and along the length of the other of the windows.
  • X driver 64 receives each of the signals 4b and 4c and has output current signals 4e and 4f that are transmitted to coils 32 and 34 by means of conductive leads 66 and 68, respectively.
  • the square wave current values of the plots 4e and 4f are l out of phase and have positive durations corresponding 7 to the durations of the current 4d along either -a positive or a negative slope. It thus readily may be appreciated that the current in coils 32 and 34 remains constant during the periods when the current represented by the plot 4d is proceeding either from a peak' to a valley or from a valley to a peak.
  • this invention provides a method of enhancing the output of an electron accelerator by making possible the generation of an electron beam of high intensity without danger of localized overheating of the beam permeable window structure through which the electron beam exits the accelerator structure.
  • This method provides for beam scanning between plural, electron permeable windows without the wastage of beam energy due to impingement of the beam on electron beam impermeable structure.
  • a method of effecting the efficient distribution of available ionizing energy from an electron beam produced in an evacuated container and directed toward at least a pair of elongate electron permeable windows arranged in a side-byside spaced apart configuration in a wall of said container comprising the steps of: scanning said beam over a predetermined time period along the length of one of said windows, instantaneously directing said beam from said one window to the other of said windows, scanning said beam over a predetermined time period along the length of said other window, and instantaneously directing said beam from said other window to said one window.

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  • Particle Accelerators (AREA)
  • Recrystallisation Techniques (AREA)
  • Electron Sources, Ion Sources (AREA)
US849705A 1969-08-13 1969-08-13 Method for increasing the output of an electron accelerator Expired - Lifetime US3679930A (en)

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US84970569A 1969-08-13 1969-08-13

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US3679930A true US3679930A (en) 1972-07-25

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US (1) US3679930A (xx)
BE (1) BE754746A (xx)
DE (1) DE2040158C3 (xx)
DK (1) DK141080B (xx)
FR (1) FR2057691A5 (xx)
GB (1) GB1324850A (xx)
NL (1) NL147578B (xx)
SE (1) SE363189B (xx)
ZA (1) ZA705583B (xx)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3856500A (en) * 1969-03-28 1974-12-24 Ppg Industries Inc Potassium polyphosphate fertilizers containing micronutrients
EP0311806A1 (en) * 1987-09-16 1989-04-19 Kabushiki Kaisha Toshiba Deflection unit for a colour cathode ray apparatus
US4935663A (en) * 1988-03-17 1990-06-19 Kabushiki Kaisha Toshiba Electron gun assembly for color cathode ray tube apparatus
US5856675A (en) * 1997-12-09 1999-01-05 Biosterile Technology, Inc. Method of irradiation of polymer films by an electron beam
WO2005055269A2 (en) * 2003-12-01 2005-06-16 Mbda Uk Limited Improvements in or relating to an electron gun and an electron beam window

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2476907A1 (fr) * 1980-02-26 1981-08-28 Razin Gennady Appareil de balayage par faisceau de particules chargees
US4293772A (en) * 1980-03-31 1981-10-06 Siemens Medical Laboratories, Inc. Wobbling device for a charged particle accelerator
DE3709462A1 (de) * 1987-03-23 1988-10-06 Polymer Physik Gmbh Ein- oder mehrstufiger elektronenbeschleuniger mit sprungstrahl
WO2001080279A1 (en) * 2000-04-13 2001-10-25 Ebara Corporation Method and apparatus for electron beam irradiation

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3066238A (en) * 1959-03-23 1962-11-27 Gen Electric Asynchronous beam scanning device

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3066238A (en) * 1959-03-23 1962-11-27 Gen Electric Asynchronous beam scanning device

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3856500A (en) * 1969-03-28 1974-12-24 Ppg Industries Inc Potassium polyphosphate fertilizers containing micronutrients
EP0311806A1 (en) * 1987-09-16 1989-04-19 Kabushiki Kaisha Toshiba Deflection unit for a colour cathode ray apparatus
US4935663A (en) * 1988-03-17 1990-06-19 Kabushiki Kaisha Toshiba Electron gun assembly for color cathode ray tube apparatus
US5856675A (en) * 1997-12-09 1999-01-05 Biosterile Technology, Inc. Method of irradiation of polymer films by an electron beam
WO2005055269A2 (en) * 2003-12-01 2005-06-16 Mbda Uk Limited Improvements in or relating to an electron gun and an electron beam window
WO2005055269A3 (en) * 2003-12-01 2005-10-13 Mbda Uk Ltd Improvements in or relating to an electron gun and an electron beam window
US20050253496A1 (en) * 2003-12-01 2005-11-17 Adam Armitage Electron gun and an electron beam window

Also Published As

Publication number Publication date
NL7011910A (xx) 1971-02-16
BE754746A (fr) 1971-01-18
DK141080C (xx) 1980-06-09
ZA705583B (en) 1971-04-28
DE2040158C3 (de) 1980-07-03
FR2057691A5 (xx) 1971-05-21
DE2040158A1 (de) 1971-02-18
SE363189B (xx) 1974-01-07
DE2040158B2 (de) 1979-10-11
DK141080B (da) 1980-01-07
NL147578B (nl) 1975-10-15
GB1324850A (en) 1973-07-25

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