US2585549A - Apparatus for accelerating electrons - Google Patents

Apparatus for accelerating electrons Download PDF

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Publication number
US2585549A
US2585549A US193498A US19349850A US2585549A US 2585549 A US2585549 A US 2585549A US 193498 A US193498 A US 193498A US 19349850 A US19349850 A US 19349850A US 2585549 A US2585549 A US 2585549A
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Prior art keywords
induction
cores
poles
magnetic
tube
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Expired - Lifetime
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US193498A
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English (en)
Inventor
Hartmann Hans
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BBC Brown Boveri AG Germany
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Bbc Brown Boveri & Cie
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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
    • H05H11/00—Magnetic induction accelerators, e.g. betatrons
    • H05H11/02—Air-cored betatrons

Definitions

  • the present invention relates to devices for accelerating electrically charged particles such as electrons to high velocity and hence high potential by means of magnetic induction effects.
  • These devices which are known generally on the European continent as ray transformers? and in theUnited States as betatrons are comprised of an evacuated annular tube into which streams of electrons are periodically injected, and an adjacently disposed magnetic system energized -by-alter-nati-ng current which produces a magnetic field varying cyclically with time and which has a spacial distribution such that the injected streams of electrons are accelerated by the field round and round the tube on an orbital path known as the equilibrium circle.
  • the magnetic field divides into two components; one component called the "induction field produces the electron acceleration; the other component called the control field produces an increasing centripetal effect upon the electrons designed to match the increasing centrifugal forcesof the electrons caused by their acceleration along the circular path thereby enabling the electron stream to be con-fined during its entire period of acceleration to an equilibrium circle .of constant position and radius.
  • the electrons which can be injected as themagnetic field produced by the alternating current wave passes through zero accelerate to an extremely high velocity by the time the magnetic field has reached its maximum value and can then be diverted .from the orbit and caused to impinge upon a target to produce X-rays or put to some other use.
  • This condition may be realized by making the reluctance .of the magnetic path greater .by an appropriate amount at the electron orbit than its average reluctance within the orbit.
  • an air gap is usually provided in that part of the magnetic circuit which carries the induction flux within the orbit.
  • the principal object of this invention is therefore to provide an improved construction for the magnetic structure of a betatron or similar device whichwill permit adjustment of a portion of the iron in the magnetic circuit after the tube has been installed in order to compen sate for any misalignment of the parts attribut-able to tube changes. or to compensate for any unavoidable faults attributable to practical difiiculties encountered in designing and building a magnetic structure which will produce an induction to control field ratio exactly as expressed by the .foregoing equation.
  • a more specific object is to provide a magnetic structure for a 'betatron wherein the magnetic iron within the electron orbit which carries the induction fiux includes a pair of inner iron cores disposed respectively on opposite sides of the air gap in the iron and which cores are adjustable longitudinally of the core axis to effect minor compensatory changes in the reluctance of the magnetic. circuit within the orbit.
  • a further object is to provide adjustable induction cores which may be displaced in a direction transverse to the core axis so as to compensate for any slight irregularity in distribution of the control field around the orbit such as may be caused by misalignment of the two confronting masses of magnetic iron which lie at the upper and lower sides of the annular electron tube.
  • Fig. 1 is a view in top plan
  • Fig. 2 is a central vertical section taken on .line 'l-.l of Fig. '2
  • Fig. 3 is a detail of the upper inner core structure.
  • the annular tube It provides therein acircular orbit kalong which the electron stream is accelerated.
  • the tube may include therein both a cathode consti-' tuting asource of the electrons and an anode against which the electron stream is caused to impinge after becoming fully accelerated, "but 1 these have, been omitted inthe interest of simplifying the drawing.
  • Tube It lies between confronting and divergently tapering faces of upper and lower annular control poles II, I2 defining the outer air gap I3 across which the electron guiding control flux component of the magnetic field passes in a direction parallel with the vertical axis :c-r of the device.
  • the induction fiux component of the magnetic field which produces the eddy field responsible for acceleration of the electron stream passes in a direction parallel with axis 33-11: as indicated by arrows I4 through the central opening of tube I0.
  • Part of this induction flux is carried through upper and lower confronting annular poles IE, IS across an annular air gap I'I' therebetween, and the remainder is carried by upper and lower confronting annular iron cores I8, I9, disposed Within the hollow center of the magnetic structure, across an annular air gap therebetween.
  • the cores I8, I9 thus form auxiliary induction poles.
  • the exciting winding which produces both the induction and control flux components of the magnetic field is comprised of upper and lower coils 2
  • , 22 are connected to a source of alternating current of suitable frequency which may for example be of the order 50 cycles per second although other frequencies have and can be used.
  • the induction fiux component set up in the induction poles I5, I6, and in the cores I8 and I9. and. the control flux component set up in control poles II, I2 close over a plurality of U-shaped yokes 25 distributed uniformly about the circumference of the cylindrical iron bodies 23, 24 in star arrangement. Eight such yokes are shown in the illustrated embodiment but more or less can be used.
  • the main induction poles I5, IS, the inner cores I8, I9 and the control poles II, I2 are fabricated from iron laminations 26 arranged vertically and stacked in planes substantially radial to the axis :c-:r.
  • the laminations of the iron bodies 23, 24 forming the main induction poles I5, I6 and the control poles II, I2 are arranged in sector-shaped stacks 21 for convenience in manufacture and assembly, and the inner cores I8, I9 are likewise preferably constituted from a plurality of sector shaped laminated stacks 28 as shown in Fig. 3. Assembly of the iron bodies 23, 24 and the yokes 25 can be in accordance with the principle disclosed in Swiss Patent No. 193,438.
  • Annular gap I1 between the annular induction poles I 5, I 6 is fixed but according to this invention the axial length of air gap 20 between the confronting end faces of the inner annular cores I8, I9 is made adjustable to the end that the induction flux component can be varied with great precision in relation to the control flux great precision in relation to the control fiux component as may be necessary to arrive at the exact ratio therebetween which is required to maintain the electron stream on the desired orbit is.
  • the induction flux component can be varied with great precision in relation to the control flux great precision in relation to the control fiux component as may be necessary to arrive at the exact ratio therebetween which is required to maintain the electron stream on the desired orbit is.
  • a similar plate 35 overlying a marginal portion of the axial opening 33 in iron body 23 serves as an anchor for the upper nut 3
  • take-up washers may have to be used between the outer end of at least one of the cores I8 or I9 and the associated plate 35 or 33 so as to enable the core and spacer assembly to be held in end-wise compression as the bolt nut 3Ib is screwed down.
  • take-up washers may have to be used between the outer end of at least one of the cores I8 or I9 and the associated plate 35 or 33 so as to enable the core and spacer assembly to be held in end-wise compression as the bolt nut 3Ib is screwed down.
  • the resiliency of pressure plates 33, 35 will be sufiicient to clamp the inner core assembly to the iron bodies 23, 24.
  • control fiux component which passes across the air gap I3 between the confronting faces of annular control poles I I, I2 at orbit k should be uniform all around the orbit so that the strength of this flux will be the same at any point on the circumference of the orbit. Otherwise, the electron stream will not receive the uniform stabilization which is required. It may well be however that in repacing the upper iron boyd 23 of the magnetic structure after a change of tube II], the workman may fail to align the upper body 23 exactly with the lower body 24 resulting in a non-uniformity of the control flux component at some sector of the orbital path k.
  • the present invention also preferably provides means for compensating for any such non-uniformity in distribution of the control flux component.
  • the present invention provides for shifting the inner core structure, which is normally arranged concentric with the energizing coils 2 I, 22, when the upper and lower bodies 23, 24 of the magnetic structure are in perfect coaxial alignment, parallel to itself in a direction transverse to the axis of coils 2 I, 22. While both the upper and lower inner cores I3, I9 could be arranged for such transverse movement to a position eccentric of the axis of the exciting coils, satisfactory compensation for non-uniform distribution of the control flux may be obtained by leaving the lower core I9 in fixed position concentric with the axis of the lower coil 22 and providing a transverse displacement only for the upper core I8 eccentrically of the upper coil 2
  • between cores [8, I9 and the iron bodies 23, 24 can be used to blow a current of air through the interior of the magnetic structure for cooling purposes.
  • all parts of the magnetic structure including the adjustable inner core are fabricated from iron laminations arranged on edge substantially radial to the vertical axis x:c of the device.
  • the magnetic flux tends to distribute itself uniformly in all radial directions from the axis .r-r. I-lence any displacement of the movable core [8 in any radial direction in compensation for misalignment expresses itself in the same manner, thus assuring a reliable reciprocal adaptation of the induction and control fluxes.
  • annular tube providing therein a closed orbital path along which the electrons are accelerated, a pair of substantially concentrically arranged annular induction poles disposed in fixed spaced relation at the central opening through said tube and which establish a fixed air gap between the confronting annular end faces thereof substantially in the plane of said tube for flow of induction flux through the tube opening, a pair of auxiliary induction cores disposed respectively within the central openings of said induction poles, the end faces of said cores also confronting each other in spaced relation to establish a second air gap therebetween substantially in the plane of said tube, one of said cores Moreover,
  • coil means energizable from a source of voltage variable with time surrounding said induction poles and disposed substantially concentric therewith.
  • auxiliary induction cores are cylinders having a diameter somewhat smaller than the diameter of the central opening through said annular induction poles to establish a radial gap therebetween, and means carried by one of said induction poles for shifting one of said cores transversely to a position eccentrically of said coil means.
  • a device for accelerating electrons as defined in claim 2 wherein the means for shifting one of said auxiliary cores includes a sleeve surrounding an end portion of the core and a plurality of adjusting screws disposed radially about and engageable with the periphery of said sleeve.
  • auxiliary induction cores are also annular and which further includes non-magnetic spacer means between the confronting faces of said cores, a bolt extending through said cores and pressure plate means on said bolt cooperative with the outer end faces of said induction poles and cores for clamping said cores in position to said induction poles.
  • an annular tube providing therein a closed orbital path along which the electrons are accelerated under the combined action of a magnetic induction flux and a magnetic control flux whose respective field strengths vary with time
  • a magnetic structure associated with said tube for providing said induction and control fluxes, said structure comprising a pair of substantially concentric cylindrical control poles disposed in confronting relation adjacent the upper and lower sides of said tube at said orbital path through which said control flux passes, substantially concentric upper and lower annular induction poles isposed radially inward from said control poles providing a path for flow of the induction flux through the central opening within said annular tube, said induction poles confronting one another in fixed and spaced relation to establish a fixed air gap therebetween substantially in the plane of said tube, upper and lower auxiliary induction cores disposed respectively within the central openings of said upper and lower annular induction poles, said cores also confronting each other in spaced relation to establish a second air gap therebetween substantially in the plane of

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Plasma & Fusion (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • Particle Accelerators (AREA)
US193498A 1949-11-02 1950-11-01 Apparatus for accelerating electrons Expired - Lifetime US2585549A (en)

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Application Number Priority Date Filing Date Title
CH704339X 1949-11-02

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CH (1) CH275605A (en))
DE (1) DE877178C (en))
GB (1) GB704339A (en))
NL (1) NL73017C (en))

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2637818A (en) * 1950-07-24 1953-05-05 Gund Konrad Electron accelerator
US2665392A (en) * 1949-10-31 1954-01-05 Gund Konrad Magnetic induction accelerator
US2812463A (en) * 1951-10-05 1957-11-05 Lee C Teng Magnetic regenerative deflector for cyclotrons
US3398308A (en) * 1964-11-19 1968-08-20 Licentia Gmbh Cyclotron device including dummy magnetic components for improved magnetic field symmetry

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0748443B2 (ja) * 1990-03-28 1995-05-24 ニチコン株式会社 電力用高圧コンデンサ

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE698867C (de) * 1935-03-06 1940-12-06 Siemens Schuckertwerke Akt Ges Vorrichtung zur Erzeugung von Elektronen hoher Energie durch das elektrische Wirbelfeld eines sich zeitlich aendernden magnetischen Hauptfeldes

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
None *

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2665392A (en) * 1949-10-31 1954-01-05 Gund Konrad Magnetic induction accelerator
US2637818A (en) * 1950-07-24 1953-05-05 Gund Konrad Electron accelerator
US2812463A (en) * 1951-10-05 1957-11-05 Lee C Teng Magnetic regenerative deflector for cyclotrons
US3398308A (en) * 1964-11-19 1968-08-20 Licentia Gmbh Cyclotron device including dummy magnetic components for improved magnetic field symmetry

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DE877178C (de) 1953-05-21
GB704339A (en) 1954-02-17
NL73017C (en))
CH275605A (de) 1951-05-31

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