US2675470A - Electron accelerator - Google Patents

Electron accelerator Download PDF

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Publication number
US2675470A
US2675470A US87021A US8702149A US2675470A US 2675470 A US2675470 A US 2675470A US 87021 A US87021 A US 87021A US 8702149 A US8702149 A US 8702149A US 2675470 A US2675470 A US 2675470A
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United States
Prior art keywords
magnetic
alternating current
control
tube
electron
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Expired - Lifetime
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US87021A
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English (en)
Inventor
Wideroe Rolf
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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
    • H05H11/04—Biased betatrons

Definitions

  • the present invention relates to devices for accelerating electrons to high velocity and high energy levels which are useful in general nuclear research activities, therapy and radiography.
  • the mass cf the electron does not begin to increase appreciably until the velocity curve begins to level ofi' rather atly at about 95 of the maximum. Thereafter, the mass rises steadily with an increase in applied energy so that when the electron has reached an energy level of about 100 million volts, its mass will have been increased to about 197 times over that which it had at rest.
  • betatron One disadvantage of the betatron is that the size oi the magnetic structure which carries the magnetic ⁇ held varies with the energy level de sired to be reached. Hence the higher the nal energy level the larger and more expensive becornes the magnetic structure.
  • the electrons are spread around the orbit but when the high frequency held is switched in, the electrons become hunched together and all reach the gap when the far side thereof is charged positively and are thereby drawn across the gap with an attendant gain in energy. Thereafter, the electrons gain incrementally in energy each time they complete a revolution around their orbit and recross the high frequency gap and llnally are diverted from the orbit to be used for the particular purpose desired.
  • the object of this invention is to provide an improved construction for the magnetic structure of the synchrotron which makes it possible to overcome the disadvantages inherent in the conventional construction wherein both the inducing and control magnetic elds are produced from the same winding.
  • the relatively low frequency power source is used only for the purpose of providing the time varied magnetic control field component for keeping the electrons on their orbit, and the magnetic inducing field essential to betatron operation is supplied by a current of a relatively higher frequency.
  • Fig. l is a view in vertical central section of one embodiment
  • Fig. 2 is a plot of magnetic ilux curves related to the Fig. 1 construction
  • Fig. 3 is likewise a view in vertical central section of a slightly modiiied construction
  • Fig. 4 is a plot of magnetic ilux curves related to the Fig. 3 construction
  • Figs. 5 and 6 are views in half central vertical section illustrating modifications of the Fig. 3 construction.
  • the synchrotron is seen to include a cylindrical array of substantially C-shaped laminated plates I of magnetic material, a toroidly shaped, evacuated glass tube 2 located between the confronting annular pole faces 3-3 formed by the inner legs 4, 4 of the C-shaped plates, and an energizing winding split into two annular coil sections 5, 5 located in the space between the inner legs 4, t and the outer legs 6 which form the yoke for completing the closed path of the magnetic flux through the plates.
  • Electrons are emitted periodically in timed relation with the time-Varied magnetic eld set up in the magnetic structure from an electron gun 9 located to one side of the orbit 7c in tube 2 along which the electrons are to be accelerated, and the tube 2 includes an oscillator driven resonant cavity section which provides a high frequency gap across which the electrons are pulled each revolution for increasing their energy after the initial acceleration by the magnetic induction principle (betatron operation) ⁇ has terminated.
  • the specific construction of the cavity nor the manner for switching in the same are of concern here insofar as the present invention is concerned they have accordingly not been included in the interest of simplifying the drawings.
  • One practical form, however, is shown and described in an article entitled Atomic Artillery that appears in the June 1947 issue or the General Electric Review.
  • the inducing field at higher frequency is set up in a separate magnetic structure II which as illustrated has the form of a hollow rectangle made up from laminated plates.
  • One leg Ila of the core passes axially through the opening Ill and has a coil I2 wound thereon which is connected in series with the energizing coils v5 5.
  • the winding I2 has the same number of turns as coils 5--5' combined and its winding direction is opposite to that of the coils 5 5 thus establishing a magnetic eld which not only opposes or bucks the eld produced by coils 5--5 but is of the same magnitude so as to prevent the latter from setting up any inducing field component in the separate core leg IIa.
  • the control field and the inducing eld are maintained entirely independent of one another. Consequently the control iield which threads the tube 2 between poles 4--4' closes through the outer legs 6 as indicated by the flux path 4) depicted in Fig. 1.
  • the inducing eld to be set up in the core leg IIa is produced by a coil I3 which surrounds leg I Ib of the separate core II.
  • Coil IS connected via switch I4 to a source I5 of alternating current of the same phase and frequency as the source 'l and a condenser I5 is connected across the source I5.
  • switch I4 is illustrated as being of the blade type, the switch in practice would be of the thyratron or similar type as shown in 3 and so controlled that it closes at the instant when the magnetic control flux produced in the control poles 4 4' passes through the zero point in its cycle and at which instant the electron stream is injected into the tube.
  • the wavelength of the inducing field, i. e. magnetic flux q curve set up in the core II is about one fourth that of the control field, i. e.. magnetic flux curve 1, is constituted by a succession of pulses; having a 'repetition rate equal -to the frequency -of the; control field and attainsra much lowerA .maximum amplitude.
  • both fluxes gb and v151y have substantially the same slope and vary in like manner with time, so that in this neighborhood, the necessary 1:2 relation between the control and inducing rfield components essential to operation on the beta-tron prin-- ciple, and which is explained in the aforementioned Steenbeek patent, can be established without diiilculty through proper selection of the peak amplitudeof the voltage at source
  • Fig. 3 shows another practical construction for asynchrotron embodying the principles of the invention.
  • the magnetic structure of the synchrotron differsfrom vthat shown in Fig. l in that the central leg l8- in which. the inducing field is produced is structurally united with the control ⁇ poles IS--IS' by means of inner yokes 20--26 in addition to the outer yokes 2i.
  • the central leg I8 is surrounded by a coil 22 and the latter contains a few less turns than the magnetizing coils 23-23 to-assure that none of the flux produced by the latter coils closes through the central leg I8. That is, all of the flux which passes through the control poles lil-IS. is returned via the outer yokes 2 I. only.
  • Coils 22 and 23--23 are arranged in series and connected to a source of alternating current 24 of relatively low frequency, .and a Wattless power condenser 25 is connectedacross the coils in the same manner and for the samey purposeas condenser 8 in the-Fig. l construction.
  • the circuit for producing the higher frequency current for establishing the inducing field in the central leg I8 is comprised of anY autotransformer 25 connected across the alternating current source 24, a condenser 2.1 connected for energization periodically from the autotransformer, and a pair of thyratron tubes 28, 29 connected in parallel and arranged in front-to-back relation for periodically discharging the condenser 2l through coil 22'.
  • Condenser 21 thus corresponds in function to condenser I6 in Fig. l.
  • a saturable core peaking transformer 30 For switching in the thyratrons alternately at the proper instant in each half wave of the magnetic control flux produced in the control poles lr--IB by coils 23-23, a saturable core peaking transformer 30 is utilized.
  • the latter includes a primary windiru.; ⁇ 3l on core 32 connected in series with coils 22, 23-23 and two secondary windings 33, 343, Wound in relatively opposite directions.
  • One side of winding 33 is connected through a direct current biasing battery 35 to 'the cathode 23a of thyratron tube 28 and the other side therecf to the control grid 28h of such tube; the grid 29h and cathode 29a. of thyratron 29 are connected in a similar manner through biasing battory 3S to the terminal ends of the transformer secondary 34.
  • resistor 39 is connected in the circuit between the thyratrons 28, 29 and one side of the coil 22.
  • the effect of this resistor is to. flatten out the slope of the flux curve c4.
  • a device foi ⁇ accelerating electrons to high energy levelsy and in which an initial acceleration to substantially the speed of light is effected through magnetic induction
  • the combination comprising, an annular evacuated tube providing a closed orbital path for electron travel, a magnetic structure associated with said tube and which includes a central core extending axially through said tube, a pair of control poles confronting each other on opposite sides of said tube at said orbital path and yoke means disposed radially outwardv of 'said control poles and connectedtherewith, a main winding surrounding said control poles and adapted to be energized by a first. alternating current of relative r' low.
  • ⁇ and means including winding means associated with said ⁇ central core arranged for energization from a source of a second alternating current having a wavelength substantially shorter than that of said first alternating current, said second alternating current being applied to said winding means in pulse form having a repetition rate equal to the frequency of said first alternating current and which produces a time varied magnetic inducing field in said central core in phase with said magnetic control field as the latter passes through the zero point in its wave.
  • An electron accelerator as defined in claim 4 wherein the said periodic discharge of said ccndenser is effected through a grid-controlled electric discharge valve of the thyratron type and in which the grid voltage varies with and reaches the ignition point of said valve when said time varied contro1 field passes through zero.
  • a device for accelerating electrons to high energy levels and in which an initial acceleration to substantially the speed of light is effected through magnetic induction comprising, an annular evacuated tube providing a closed orbital path for electron travel, a unitary magnetic structure associated with said tube comprising a central core extending axially through said tube and provided with an air gap and a pair of confronting control poles disposed on opposite sides of said tube at said orbital path, yoke means disposed radially outward of said control poles, a main energizing winding surrounding said control poles and adapted to be energized from a first relatively low frequency alternating current to produce a time varied magnetic control field in said control poles, an auxiliary winding surrounding said central core, said auxiliary Winding having the same number of turns as said main winding and connected in series therewith for producing a field in said core bucking and nullifying the field which otherwise would be produced in said core by said main winding whereby said control field closes through said yoke means

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Plasma & Fusion (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • Particle Accelerators (AREA)
US87021A 1948-07-28 1949-04-12 Electron accelerator Expired - Lifetime US2675470A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CH661247X 1948-07-28

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US2675470A true US2675470A (en) 1954-04-13

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US87021A Expired - Lifetime US2675470A (en) 1948-07-28 1949-04-12 Electron accelerator

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US (1) US2675470A (en, 2012)
CH (1) CH268673A (en, 2012)
DE (1) DE842519C (en, 2012)
FR (1) FR991920A (en, 2012)
GB (1) GB661247A (en, 2012)
NL (1) NL75180C (en, 2012)

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2839680A (en) * 1952-05-14 1958-06-17 Bbc Brown Boveri & Cie Process and device for testing materials by means of energy-rich x-rays
US2956195A (en) * 1959-08-14 1960-10-11 John S Luce Hollow carbon arc discharge
US2964627A (en) * 1957-07-01 1960-12-13 Trub Tauber & Co A G Double-focussing spectrometer for electrically charged particles
US3031596A (en) * 1958-03-13 1962-04-24 Csf Device for separating electrons in accordance with their energy levels
US3036963A (en) * 1960-01-25 1962-05-29 Nicholas C Christofilos Method and apparatus for injecting and trapping electrons in a magnetic field
US3255369A (en) * 1959-06-20 1966-06-07 Commissariat Energie Atomique Variable polarization saturable magnetic circuits
US3255404A (en) * 1961-05-29 1966-06-07 Robert P Kidwell Electrical energy transmission system
US20070182498A1 (en) * 2006-02-06 2007-08-09 Mitsubishi Electric Corporation Electromagnetic wave generating device
US20090153279A1 (en) * 2007-12-14 2009-06-18 Schlumberger Technology Corporation Single drive betatron
US20090267542A1 (en) * 2006-10-28 2009-10-29 Bermuth Joerg Betatron with a variable orbit radius
US20090267543A1 (en) * 2006-10-28 2009-10-29 Bermuth Joerg Betatron with a removable accelerator block
US20100148705A1 (en) * 2008-12-14 2010-06-17 Schlumberger Technology Corporation Method of driving an injector in an internal injection betatron

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1097052B (de) * 1958-08-30 1961-01-12 Licentia Gmbh Einrichtung zur Erzeugung periodischer, durch das eigene Magnetfeld eingeschlossener Gasentladungen hoher Stromstaerke
BE639169A (en, 2012) * 1962-11-02
US3975689A (en) * 1974-02-26 1976-08-17 Alfred Albertovich Geizer Betatron including electromagnet structure and energizing circuit therefor

Citations (6)

* 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
US2394072A (en) * 1943-09-10 1946-02-05 Gen Electric Electron accelerator control system
US2465786A (en) * 1947-01-24 1949-03-29 Gen Electric Accelerating apparatus for charged particles
US2480169A (en) * 1946-10-26 1949-08-30 Gen Electric Apparatus for imparting high energy to charged particles
US2533859A (en) * 1943-07-14 1950-12-12 Bbc Brown Boveri & Cie Improved injection system for magnetic induction accelerators
US2535710A (en) * 1942-06-17 1950-12-26 Gen Electric Controller for magnetic induction accelerators

Patent Citations (6)

* 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
US2535710A (en) * 1942-06-17 1950-12-26 Gen Electric Controller for magnetic induction accelerators
US2533859A (en) * 1943-07-14 1950-12-12 Bbc Brown Boveri & Cie Improved injection system for magnetic induction accelerators
US2394072A (en) * 1943-09-10 1946-02-05 Gen Electric Electron accelerator control system
US2480169A (en) * 1946-10-26 1949-08-30 Gen Electric Apparatus for imparting high energy to charged particles
US2465786A (en) * 1947-01-24 1949-03-29 Gen Electric Accelerating apparatus for charged particles

Cited By (17)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2839680A (en) * 1952-05-14 1958-06-17 Bbc Brown Boveri & Cie Process and device for testing materials by means of energy-rich x-rays
US2964627A (en) * 1957-07-01 1960-12-13 Trub Tauber & Co A G Double-focussing spectrometer for electrically charged particles
US3031596A (en) * 1958-03-13 1962-04-24 Csf Device for separating electrons in accordance with their energy levels
US3255369A (en) * 1959-06-20 1966-06-07 Commissariat Energie Atomique Variable polarization saturable magnetic circuits
US2956195A (en) * 1959-08-14 1960-10-11 John S Luce Hollow carbon arc discharge
US3036963A (en) * 1960-01-25 1962-05-29 Nicholas C Christofilos Method and apparatus for injecting and trapping electrons in a magnetic field
US3255404A (en) * 1961-05-29 1966-06-07 Robert P Kidwell Electrical energy transmission system
US20070182498A1 (en) * 2006-02-06 2007-08-09 Mitsubishi Electric Corporation Electromagnetic wave generating device
US7619375B2 (en) * 2006-02-06 2009-11-17 Mitsubishi Electric Corporation Electromagnetic wave generating device
US7994740B2 (en) * 2006-10-28 2011-08-09 Smiths Heimann Gmbh Betatron with a removable accelerator block
US20090267542A1 (en) * 2006-10-28 2009-10-29 Bermuth Joerg Betatron with a variable orbit radius
US20090267543A1 (en) * 2006-10-28 2009-10-29 Bermuth Joerg Betatron with a removable accelerator block
US8013546B2 (en) * 2006-10-28 2011-09-06 Smiths Heimann Gmbh Betatron with a variable orbit radius
US20090153279A1 (en) * 2007-12-14 2009-06-18 Schlumberger Technology Corporation Single drive betatron
US7638957B2 (en) * 2007-12-14 2009-12-29 Schlumberger Technology Corporation Single drive betatron
US20100148705A1 (en) * 2008-12-14 2010-06-17 Schlumberger Technology Corporation Method of driving an injector in an internal injection betatron
US8362717B2 (en) 2008-12-14 2013-01-29 Schlumberger Technology Corporation Method of driving an injector in an internal injection betatron

Also Published As

Publication number Publication date
GB661247A (en) 1951-11-21
NL75180C (en, 2012)
DE842519C (de) 1952-06-26
FR991920A (fr) 1951-10-11
CH268673A (de) 1950-05-31

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