US2663813A - Magnetic induction accelerator - Google Patents

Magnetic induction accelerator Download PDF

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Publication number
US2663813A
US2663813A US198325A US19832550A US2663813A US 2663813 A US2663813 A US 2663813A US 198325 A US198325 A US 198325A US 19832550 A US19832550 A US 19832550A US 2663813 A US2663813 A US 2663813A
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United States
Prior art keywords
tube
conductors
magnetic
bands
magnetic induction
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Expired - Lifetime
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US198325A
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English (en)
Inventor
Wideroe Rolf
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BBC Brown Boveri AG Germany
BBC Brown Boveri France SA
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BBC Brown Boveri France SA
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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
    • H05H11/04—Biased betatrons

Definitions

  • This invention relates in general to devices for accelerating charged particles such as a stream of electrons to high velocity and hence high potential on an orbital path by the principle of magnetic induction.
  • Electron accelerators of the magnetic induction type now generally known as a betatron or ray transformer are comprised of an evacuated toroidal tube into which electrons are introduced from an electron emissive cathode or electron gun, and a magnetic system which produces a magnetic field varying with time having a space distribution such that the injected elecn trons are accelerated by the iield along a circular orbit.
  • the magnetic iield divides into components, one component being known as the induction field which produces the electron acceleration and the other as the control or guiding iield which produces a centripetal effect upon the electrons to offset the centrifugal forces resulting from the circular motion.
  • the electrons reach an enormously high energy level at which time they can then be diverted from the orbit for producing desired results such as for example to bombard a target and produce Xrays.
  • the radial eld components above and below the plane in which it is calculated the orbital path will lie should be of like magnitude and exactly opposite one another.
  • this ideal relationship is not always possible. For example, if it should happen that a removable part of the magnetic structure above the tube is not aligned exactly with the corresponding structural part below the tube when initially installed or when replaced after lhaving been removed to replace the tube, the mis-alignment between the two parts may cause the orbit to become established in a plane other than the one calculated for it with a possible attendant loss of those electrons in the stream which should happen to impinge against the wall of the tube in the course of their range of normal oscillatory displacement from the orbital path during their acceleration along the path. Other factors may also result in impingement of some electrons in the stream upon the tube wall thus reducing the potential yield of the electron stream.
  • the general objective of the present invention is to prevent any reduction in yield of the electron stream, and is attained through the use of like circularly curved conductors disposed respectively above and below the equatorial plane of the tube and which are counter-connected, i. e. short-circuited with each other.
  • Fig. 1 is a view in vertical diametral section on line l-I or Fig. 2 through a magnetic induction accelerator in which the short circuited, arcuate conductors, located respectively above and below the equatorial plane of the annular tube are comprised of a plurality of interconnected sets of substantially single turn coils stepped in diameter and arranged in planes parallel with the equatorial plane.
  • Fig. 2 is a horizontal sectional View on line 2-2 of Fig. 1;
  • Fig. 3 is a View in top plan of a tube showing a modified arrangement for the leads interconnecting the corresponding conductor coils above and below the equatorial plane in opposition;
  • Fig. 4 is a view in top plan of a tube illustrating a somewhat diierent construction for the arcuate conductors in which the latter extend for only a portion of a complete circle;
  • Fig. 5 is a view in transverse section on line 5 5 of Fig. 4;
  • Fig. 6 is a view in vertical section of a further modification of the invention wherein the upper and lower short-circuited arcuate conductor sets are comprised of bands having a curvature cor-y responding to that of the lines of flux of the magnetic control field; and
  • Fig. 7 is a diagrammatic view showing the arrangement for one set of the arcuate conductors.
  • the magnetic induction accelerator is seen to be comprised of a magnetic structure I0 made up from steel laminations of appropriate contour stacked radially on edge to provide a pair of confronting cylindrical induction poles Il ll' separated by air gap l2 and located concentrically along the central Vertical axis rit-a, and a pair of confronting annular control poles I3-l3 also concentric with axis a-a with an air gap i4 therebetween.
  • Yoke members I5 complete the magnetic circuit for a cyclic, time varied magnetic flux set up in the annular and cylindrical poles.
  • the magnetic flux in the control poles constitutes the guiding or control field previously mentioned, and the iiux in the induction poles constitutes the induction field.
  • the magnetic flux is produced by a winding split into two coil sections 16-16 connected in series for energization from a source, indicated by terminals l1, of alternating current of suitable frequency as for example 100 cycles/sec.
  • Tube I8 is also concentric with axis a-a and the particular one illustrated has a substantially trapezoidal cross-section.
  • an electron emissive .cathode not shown and which may be located within the tube I8 or in an arm portion arranged tangentially thereto, streams of electrons are injected in timed relation to the time-varied magnetic field produced .in -the structure l by the time-Varied current in the energizing coils Iii-I5 and are continuously accelerated along an orb-ital path indicated by .the circle lc.
  • the electron stream Upon completion of the acceleration phase, the electron stream is thencausedtoleave the orbit and iinpinge upon an .anode also not shown to yield X-rays, or the stream may ,be removed ⁇ from the tube for other purposes as for use in an ionization chamber.
  • located above the equatorial plane -b-.b are paired with twin counterparts I6', 2e and 2l located at like spatial positions below plane b b, .and each .pair Iii'fi, 28--20 and lfi--i' are interconnected by conductor portions ica- '.la and ESB-2lb, respectively.
  • the conductor portions 2da, 21a and 2%-, Zib interconnecting arcuate conductorV shalls Z-Q-Q' and 2
  • all the interconnecting conductors could pass through the tube center, orv all could be passed over the outer side of the tube as shown in Fig. 3 wherein the various arcuate conductors havebeen given the saine reference numerals for purpose of comparison.
  • each of the arcuate conductors IQ-Zi and ⁇ Bf-2 I extends for substantially 360i and hence the interconnecting conductors l-Qaf--'Ia and 49h- 2 I-b would actually be much closer together than appears in the drawing where a rather wide spacing has been maintained for purposes of clarity.
  • 9-l9' will produce in each identical voltages e, e', respectively, as indicated in Fig. 'L and these voltages nullify one another since the two turns lB-IQV are connected in opposition. The same will be true for conductor turns 2li-26!
  • a vsomewhat diiferent arrangement for the compensating short-circuited conductors is illustrated Vin Figs. 4 and 5 wherein each of the arcuate conductors concentric with the vertical axis c c, extends over only a portion of the complete circumference.
  • Each of the six sets I-VI of paired conductors extends over 60 of arc.
  • conductors 22--26 disposed at the upper side of tube I8 are paired with and counterconnected to conductors l222' disposed .at the under side of tube i6 and located at .correspending vradial distances from axis ,ca -a.
  • connection between the conductor .pairs aredesignated 22a-26a and 22h-26h, and it will be observed that all of these connections pass over the outer side of tube i8.
  • the paired conductors the other five sets II-VI are arranged in identically the same manner as those of sety I, and lie at corresponding radial distances from -axis .a.-.a. That is, the conductors 22.-22 of .each set lie on the same radius, and the conductors 23.-23 of each set lie on the same but shorter radius, etc.
  • the .paired conductors are constituted by bands of electrically conductive, metallic strip material, preferably copper having a thickness of the order of l mm. or less and a width of the order of 5 mm. -or more.
  • the si-X radially spaced bands disposed along the upper surface of tube ,I8 concentric with axis a--a are numbered 2,8-33, and those disposed at the lower surface of the tube are numbered 28-33'.
  • the paired' conductive bands extend over an arc of substantially 360 and are interconnected by conductors 28a- 33a and 28h-33h.
  • Each band is curved in the direction of its width to lconform to the curvature of the path taken by the control field ce shown in broken lines ,between the confronting faces of the control poles Iii-i3', Basically these counter-connected bands function in the same manner as the conductor wires of the other previously described embodiments.
  • the band which also prevents, through the short-circuit eifect, the occurrence of magnetic fluxes extending perpendicularly to it, the-niagnetic control lines of force between the vbands are brought exactly Vinto the desired direction and will therefore take the desired course within the tube i3 with better approximation than can be obtainedwhen band-shaped conductors are not used.
  • the construction shown in Eig, 6 also. includes two more bands Sli, 35 disposed respectively at the inner and outer sides of tube i3 andfsymmetrically with respect to the equatorial plane. b b.
  • the strip material forming these latter bands is 'heu/isc given a curvature conforming to the path of the control flux c@ and the bandsextend inthe directicnof. thisrpath from the upper edges of the upper set of bands 21H-fst to the lower edges. ofthe lower set of bands 28h-331. Because of the relatively greater widths the two bands .3.4; 351111.-
  • the bands 34 are broken at one point in their circumference such as by narrow slots 34a and 35a, respectively.
  • the compensating conductors preferably are disposed on the exterior surface of the wall of tube i8 and may be attached to the same by any suitable adhesive such as glue or cement.
  • a magnetic induction accelerator for charged particles comprising a toroidal evacuated tube, means including a magnetic structure adjacent said tube and winding means thereon for producing a time-varying magnetic field having induction and control components of such spatial distribution relative to said tube as to normally conne electrons within the tube to a substantially circular orbit around the tube while accelerating them along said orbit, a pair of curved conductors having a like radius of curvature mounted concentric with the axis of said tube and disposed at corresponding positions above and below the equatorial plane of said tube in planes parallel with said equatorial plane, and means interconnecting said conductors in shortcircuit relation with each other whereby the voltages induced respectively therein by said magnetic iield are opposing.
  • a magnetic induction accelerator for charged particles comprising a toroidal evacuated tube, means including a magnetic structure adjacent said tube and winding means thereon for producing a time-varying magnetic i'ield having induction and control components of such spatial distribution relative to said tube as to normally confine electrons within the tube to a substantially circular orbit around the tube while accelerating them along said orbit, a plurality of pairs of curved conductors mounted concentric with the axis of said tube, each pair of conductors having a different radius of curvature and the conductors of each pair being disposed at corresponding positions above and below the equatorial plane of said tube in planes parallel with said equatorial plane, and means interconnecting the conductors of each pair in shortcircuit relation with each other whereby the voltages induced respectively therein by said magnetic field are opposing.
  • a magnetic induction accelerator for charged particles comprising a toroidal evacuated tube, means including a magnetic structure adjacent said tube and winding means thereon for producing a time-varying magnetic iield having induction and control components or" such spatial distribution relative to said tube as to normally conne electrons within the tube to a substantially circular orbit around the tube while accelerating them along said orbit, a pair of curved bands of electrically conductive metallic strip material having a like radius of curvature mounted ccncentric with the axis of said tube and disposed at corresponding positions above and below the equatorial plane of said tube parallel with said equatorial plane, said bands being also curved in the direction of their width to coincide with the curvature of the path taken by the control component of said magnetic iield; and means interconnecting said bands in short-circuit relation with each other whereby the voltages induced respectively therein by said magnetic neld are opposing.
  • a magnetic induction accelerator for charged particles comprising a toroidal evacuated tube, means including a magnetic structure adjacent said tube and winding means thereon for producing a time-varying magnetic field having induction and control components oi such spatial distribution relative to said tube as to normally confine electrons Within the tube to a substantia-lly circular orbit around the tube while accelerating them along said orbit, a plurality of pairs of curved bands of electrically conductive metallic strip material mounted concentric with the axis of said tube, each pair of bands having a diierent radius of curvature and the conductors of each pair being disposed at corresponding positions above and below the equatorial plane of said tube parallel with said equatorial plane, said bands being also curved in the direction of their width to coincide with the curvature of the path taken by the control component or said magnetic field, and means interconnecting the bands of each pair in short-circuit relation with each other whereby the voltages induced respectively therein by said magnetic field are opposing.

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Plasma & Fusion (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • Particle Accelerators (AREA)
  • X-Ray Techniques (AREA)
US198325A 1949-12-02 1950-11-30 Magnetic induction accelerator Expired - Lifetime US2663813A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CH693307X 1949-12-02

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US2663813A true US2663813A (en) 1953-12-22

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US (1) US2663813A (el)
CH (1) CH277136A (el)
DE (1) DE908394C (el)
FR (1) FR1028434A (el)
GB (1) GB693307A (el)
NL (1) NL72582C (el)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2929951A (en) * 1958-04-28 1960-03-22 Finkelstein David Ion-stabilized electron induction accelerator
US3263136A (en) * 1964-01-20 1966-07-26 Hayden S Gordon High energy accelerator magnet structure
US5347254A (en) * 1993-03-08 1994-09-13 The United States Of America As Represented By The Secretary Of The Army Tubular structure having transverse magnetic field with gradient
WO2008052614A1 (de) * 2006-10-28 2008-05-08 Smiths Heimann Gmbh Betatron mit contraction- und expansion-spule

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2394070A (en) * 1942-06-02 1946-02-05 Gen Electric Magnetic induction accelerator
US2447255A (en) * 1944-05-04 1948-08-17 Univ Illinois Magnetic induction accelerator with small X-ray source
US2558597A (en) * 1945-09-15 1951-06-26 Gen Electric Field correction in magnetic induction accelerators
US2622194A (en) * 1950-11-18 1952-12-16 Gen Electric Apparatus for accelerating charged particles

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2331788A (en) * 1942-01-20 1943-10-12 Gen Electric Magnetic induction accelerator

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2394070A (en) * 1942-06-02 1946-02-05 Gen Electric Magnetic induction accelerator
US2447255A (en) * 1944-05-04 1948-08-17 Univ Illinois Magnetic induction accelerator with small X-ray source
US2558597A (en) * 1945-09-15 1951-06-26 Gen Electric Field correction in magnetic induction accelerators
US2622194A (en) * 1950-11-18 1952-12-16 Gen Electric Apparatus for accelerating charged particles

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2929951A (en) * 1958-04-28 1960-03-22 Finkelstein David Ion-stabilized electron induction accelerator
US3263136A (en) * 1964-01-20 1966-07-26 Hayden S Gordon High energy accelerator magnet structure
US5347254A (en) * 1993-03-08 1994-09-13 The United States Of America As Represented By The Secretary Of The Army Tubular structure having transverse magnetic field with gradient
WO2008052614A1 (de) * 2006-10-28 2008-05-08 Smiths Heimann Gmbh Betatron mit contraction- und expansion-spule
US20090268872A1 (en) * 2006-10-28 2009-10-29 Bermuth Joerg Betatron with a contraction and expansion coil
US8073107B2 (en) 2006-10-28 2011-12-06 Smiths Heimann Gmbh Betatron with a contraction and expansion coil
RU2516293C2 (ru) * 2006-10-28 2014-05-20 Смитс Хайманн Гмбх Бетатрон с катушкой сжатия и расширения

Also Published As

Publication number Publication date
GB693307A (en) 1953-06-24
CH277136A (de) 1951-08-15
DE908394C (de) 1954-04-05
NL72582C (el)
FR1028434A (fr) 1953-05-22

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