US3567924A - Method and apparatus for bombardment of a target by modulated circular sweeping - Google Patents

Method and apparatus for bombardment of a target by modulated circular sweeping Download PDF

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Publication number
US3567924A
US3567924A US664184A US3567924DA US3567924A US 3567924 A US3567924 A US 3567924A US 664184 A US664184 A US 664184A US 3567924D A US3567924D A US 3567924DA US 3567924 A US3567924 A US 3567924A
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Prior art keywords
target
accordance
charged particles
voltages
varying
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US664184A
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English (en)
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Guy Moisand
Michel Roche
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Commissariat a lEnergie Atomique et aux Energies Alternatives CEA
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Commissariat a lEnergie Atomique CEA
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    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05H—PLASMA TECHNIQUE; PRODUCTION OF ACCELERATED ELECTRICALLY-CHARGED PARTICLES OR OF NEUTRONS; PRODUCTION OR ACCELERATION OF NEUTRAL MOLECULAR OR ATOMIC BEAMS
    • H05H3/00—Production or acceleration of neutral particle beams, e.g. molecular or atomic beams
    • H05H3/06—Generating neutron beams
    • G—PHYSICS
    • G06—COMPUTING OR CALCULATING; COUNTING
    • G06G—ANALOGUE COMPUTERS
    • G06G7/00—Devices in which the computing operation is performed by varying electric or magnetic quantities
    • G06G7/12—Arrangements for performing computing operations, e.g. operational amplifiers
    • G06G7/26—Arbitrary function generators
    • G06G7/28—Arbitrary function generators for synthesising functions by piecewise approximation
    • 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
    • G21K1/087—Deviation, concentration or focusing of the beam by electric or magnetic means by electrical means
    • 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
    • H01J29/70—Arrangements for deflecting ray or beam
    • H01J29/78—Arrangements for deflecting ray or beam along a circle, spiral or rotating radial line, e.g. for radar display

Definitions

  • This invention relates to a method of bombardment of a target by modulated circular sweeping wherein a bombardment which is uniform in time is carried out over the entire surface of said target by means of a perfectly focused beam of charged particles.
  • the invention is also concerned with an apparatus for the execution of said method.
  • the target may be bombarded by a deuteron beam which has been defocused so that it has approximately the same diameter as the target.
  • this method is unsatisfactory since it results in destruction of the target within a short time on account of lack of homogeneity of the beam.
  • the aim of the present invention is to prevent rapid destruction of the target by virtue of a bombardment of the target with a beam which, on the one hand, is well focused and which, on the other hand, makes it possible to distribute on said target a flux which is uniform in time, this condition being essential for the purpose of ensuring optimum utilization of the target and obtaining a strong neutron emission.
  • the present invention provides the method of uniformly bombarding a circular area of a target by a focused beam of charged particles which comprises subjecting said beam to the electric fields of two mutually perpendicularly disposed pairs of deflector plates to which are applied sinusoidal voltages mutually displaced in phase by 1r/2, the amplitude U of each of said sinusoidal voltages being modulated so that each has a value defined by the equation wherein U varies as a function of time in accordance with the relation U (t) l at b a and b being constants.
  • the invention also provides apparatus for uniformly bombarding a circular area of a target with a focus beam of charged particles comprising means for focusing said beam of charged particles upon said target, said beam in passing to said target traversing the electric fields of two mutually perpendicularly disposed pairs of deflector plates, means for generating and applying to said pairs of deflector plates sinusoidally varying voltages mutually displaced in phase by 1r/2, the amplitude U of each of said voltages varying in accordance with the equation where U,,(t) x at b, and a and b are constants.
  • the means for generating the varying voltages includes a variable capacitor which is included in a resonant circuit included in a tuned amplifier FIG.); way of which said sinusoidal voltages are fed to said deflector plates, the moving plate of said capacitor having a contour of which the form is such that as said plate is continuously rotated the capacitance of said capacitor varies cyclically with time in such a manner that the amplitude U, of the sinusoidal voltage has a value represented by the expression U 0) /at b, where a and b are constants.
  • said function generator comprises a Zener diode which is swept by a triangular current.
  • FIG. 1 is a diagrammatic view in perspective of a circular sweep system of known type which is intended to receive the apparatus in accordance with the invention not shown in the FIG);
  • FIG. 2 is a diagram of the amplifier of said circular sweep system on which is mounted a variable capacitor constituting a first embodiment of the function'generator in accordance with the invention
  • FIGS. 3 to 5 show three curves which serve to determine the shape to be given to the contour of the moving plate of the variable capacitor of FIG. 2;
  • FIG. 6 is a diagram showing the manner in which the contour of the moving plate of said variable capacitor is defined in practice
  • FIG. 7 is a circuit diagram of a purely electronic construction of the function generator according to the invention which is intended to produce the desired parabolic variation of U as a function of time and, finally;
  • FIG. 8 shows a form of construction of the focusing and centering device of the apparatus according to the invention.
  • the voltage applied to the pair of deflector plates 1 has the form it is required that the beam should be well focused on the target and that U, should be varied as a function of time according to a law such that the flux should be uniform in time over the entire surface of the target 3.
  • the sweep radius is expressed by the standard formula wherein L is the distance from the center of the pair of plates 1 to the target 3,
  • l is the length of the platesl (forexample 5 cms) and h is the distance between said plates (for example 2 cms).
  • the apparatus in accordance with the invention accordingly comprises a function generator which serves to execute the above-mentioned parabolic variation of U (t).
  • said function generator consists of a variable capacitor specially designed for producing said variation of U, (t) and which is mounted in the amplifier of the circular sweep system.
  • the desired modulation is effected by producing a variation in the capacitance of said capacitor and consequently in the tuning capacitance of said amplifier.
  • the amplifier as shown in FIG. 2 comprises an amplifier tube 4, the variable or modulation capacitor which is characteristic of the invention, a second variable capacitor 6, an inductance coil 7, and a voltage step-up transformer 8 supplied by a quartz generator (not shown).
  • the tuning capacitance is constituted by 1. the modulation capacitance C of the capacitor 5;
  • variable capacitance of the capacitor 6 which must make it possible to compensate the capacitance of the deflector plates 1 and 2;
  • the modulation capacitor 5 is driven in rotation by an electric motor 9 at a speed of approximately 3000 r.p.m.
  • condition of uniform flux which is characteristic of the invention is satisfied if the condition (as shown in FIG. 4)-, is plotted as a function of t.
  • the modulation capacitor 5" is given a form which makes it possible to obtain this variation of C as a function of time.
  • the fixed plate of the modulation capacitor is given the shape of a semicircle, the radius of which is greater than the maximum radius of the moving plate.
  • the plate 14 from which the moving plate will be cut and which has a straight edge D there are plotted from a point 0 of said straight edge, straight lines which divide the plate 14 into n sectors (n having the same value as above).
  • the radii r,- being thus determined, it merely remains to cut out the plate 14 on which said radii have been drawn, starting from the point 0 and following the extremities of the different radii r,-.
  • the function generator in accordance with the invention which serves to produce the timedependent parabolic variation of the form U (t) V at b is purely electronic and comprises a Zener diode which is swept by a triangular current.
  • Said Zener diode is chosen so that the knee of its reverse characteristic is sufficiently rounded and is biased in the region of said knee.
  • a current corresponding to the difference between the collector currents of T, and T is passed through the diode Z which is shown in FIG. 7; inasmuch as the collector current of T is constant, the desired result will be obtained if the current of T varies in a triangle.
  • FIG. 8 shows a form of construction of a device for facilitating the checking of the focusing and centering the beam of particles (deuterons) which is projected onto the target 3.
  • the device comprises:
  • a copper diaphragm 10 which is provided with a cruciform slot and which is designed to swing back in front of the target 3 in such a manner that the center of the cruciform slot is located exactly on the axis of the target.
  • Said diaphragm is insulated by a thin strip 13 of mica (having a thickness of approximately 0.5 mm.) from a copper disc 11 having the same diameter as the useful portion of the target 3 on which the pulses are collected.
  • the diaphragm 10 is cooled by being in close contact with the shaft 12 through which water is circulated.
  • the distance between the disc 11 and the target 3 must be as small as possible (less than 1 centimeter).
  • Adjustment of focusing of the beam is carried out as follows: by executing a horizontal sweep of the target followed by a vertical sweep, signals are obtained which represent; two diameters of the beam measured along the two arms of the cruciform slot of the diaphragm 10; adjustment is then affected to make said diameters as small as possible and of equal value.
  • the sweeping is performed in the direction of horizontal deflection and only a single impulse should be seen (the vertical centering voltage being accordingly modified), whereupon the reverse operation is performed and centering is carried out b modifying the wherein U varies as a function of time in accordance with the relation U (t) V at b, a and b being constants.
  • Apparatus for uniformly bombarding a circular area of a target with a focused beam of charged particles comprising means for focusing said beam of charged particles upon said target, said beam in passing to said target traversing the electric fields of two mutually perpendicularly disposed pairs of deflector plates, means for generating and apglying to said pairs of deflector plates sinusoidally varying vo ges mutually displaced in phase by 1r/2, the amplitude U of each of said voltages varying in accordance with the equation where U, (t) at+b, and a and b are constants.
  • Apparatus in accordance with claim 2 including a device for determining the focusing and centering of the beam of charged particles arranged to be selectively disposed between the source of said beam and said target.
  • the means for generating said varying voltages includes a variable capacitor in a resonant circuit in a tuned amplifier through which said sinusoidal voltages are fed to said deflector plates, the moving plate of said capacitor having a contour of which the form is such that as said plate is continuously rotated the capacitance of said capacitor varies cyclically with time in such a manner that the amplitude U, of the sinusoidal volta es has a value represented by the expression U, (t) a t wherein a and b are constants.
  • Apparatus in accordance with claim 2 wherein said means for varying the amplitude of said sinusoidal voltages includes a Zener diode through which a cyclically varying current of triangular waveform is passed.
  • Apparatus in accordance with claim 2 including a device for determining the focusing and centering said beam selectively positionable to intercept said beam in the neighborhood of the target, said device comprising a metallic diaphragm pierced by a cruciform slot the intersection of which defines the center of the target and a plate insulated from said diaphragm and positioned to receive charged particles passing through said slot.

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • Mathematical Physics (AREA)
  • High Energy & Nuclear Physics (AREA)
  • Theoretical Computer Science (AREA)
  • General Physics & Mathematics (AREA)
  • Computer Hardware Design (AREA)
  • Software Systems (AREA)
  • Plasma & Fusion (AREA)
  • General Engineering & Computer Science (AREA)
  • Radar, Positioning & Navigation (AREA)
  • Remote Sensing (AREA)
  • Particle Accelerators (AREA)
  • Control Of Indicators Other Than Cathode Ray Tubes (AREA)
  • Facsimile Scanning Arrangements (AREA)
US664184A 1966-09-16 1967-08-29 Method and apparatus for bombardment of a target by modulated circular sweeping Expired - Lifetime US3567924A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
FR76732A FR1504593A (fr) 1966-09-16 1966-09-16 Procédé de bombardement d'une cible par balayage circulaire modulé et appareil correspondant

Publications (1)

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US3567924A true US3567924A (en) 1971-03-02

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US664184A Expired - Lifetime US3567924A (en) 1966-09-16 1967-08-29 Method and apparatus for bombardment of a target by modulated circular sweeping

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US (1) US3567924A (enrdf_load_stackoverflow)
BE (1) BE702926A (enrdf_load_stackoverflow)
CH (1) CH482297A (enrdf_load_stackoverflow)
DE (1) DE1589634B2 (enrdf_load_stackoverflow)
ES (1) ES345051A1 (enrdf_load_stackoverflow)
FR (1) FR1504593A (enrdf_load_stackoverflow)
GB (1) GB1151825A (enrdf_load_stackoverflow)
LU (1) LU54436A1 (enrdf_load_stackoverflow)
NL (1) NL6712260A (enrdf_load_stackoverflow)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3688203A (en) * 1970-11-10 1972-08-29 Kev Electronics Corp Scanning system for ion implantation accelerators
US6380545B1 (en) * 1999-08-30 2002-04-30 Southeastern Universities Research Association, Inc. Uniform raster pattern generating system

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102010035925A1 (de) * 2010-08-31 2012-03-01 Siemens Aktiengesellschaft Kontrolle der Energiedichte in einem 'Target eines Teilchenbeschleunigers

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3688203A (en) * 1970-11-10 1972-08-29 Kev Electronics Corp Scanning system for ion implantation accelerators
US6380545B1 (en) * 1999-08-30 2002-04-30 Southeastern Universities Research Association, Inc. Uniform raster pattern generating system

Also Published As

Publication number Publication date
ES345051A1 (es) 1970-04-01
FR1504593A (fr) 1967-12-08
GB1151825A (en) 1969-05-14
CH482297A (fr) 1969-11-30
DE1589634B2 (de) 1972-01-05
NL6712260A (enrdf_load_stackoverflow) 1968-03-18
LU54436A1 (enrdf_load_stackoverflow) 1967-11-07
BE702926A (enrdf_load_stackoverflow) 1968-01-15
DE1589634A1 (de) 1970-05-21

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