US2465786A - Accelerating apparatus for charged particles - Google Patents

Accelerating apparatus for charged particles Download PDF

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Publication number
US2465786A
US2465786A US724066A US72406647A US2465786A US 2465786 A US2465786 A US 2465786A US 724066 A US724066 A US 724066A US 72406647 A US72406647 A US 72406647A US 2465786 A US2465786 A US 2465786A
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United States
Prior art keywords
coils
orbit
field
accelerating
electrons
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Expired - Lifetime
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US724066A
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English (en)
Inventor
John P Blewett
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General Electric Co
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General Electric Co
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Filing date
Publication date
Priority to BE479999D priority Critical patent/BE479999A/xx
Priority to BE507189D priority patent/BE507189A/xx
Priority to FR962863D priority patent/FR962863A/fr
Priority to US724066A priority patent/US2465786A/en
Application filed by General Electric Co filed Critical General Electric Co
Priority to GB2296/48A priority patent/GB665828A/en
Application granted granted Critical
Publication of US2465786A publication Critical patent/US2465786A/en
Priority claimed from US196482A external-priority patent/US2622194A/en
Priority to CH298296D priority patent/CH298296A/de
Priority to DEI4861A priority patent/DE900853C/de
Priority to GB27086/51A priority patent/GB711916A/en
Priority to FR62813D priority patent/FR62813E/fr
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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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
    • 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
    • H05H13/00—Magnetic resonance accelerators; Cyclotrons
    • H05H13/04—Synchrotrons
    • 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
    • H05H7/00—Details of devices of the types covered by groups H05H9/00, H05H11/00, H05H13/00

Definitions

  • the present invention comprises an improved apparatus for accelerating charged particles and in particular to electrons.
  • Kerst Patent 2,297,305 issued September 29, 1942, and other patents of later dated, describe magnetic induction accelerating apparatus whereby charged particles are accelerated in an annular chamber by a magnetic field, the apparatus including a magnetic core of iron which is interlinked with the acceleration orbit in the annular chamber.
  • the iron core which forms partof conventional accelerating apparatus presents some disadvantages.
  • Such an iron core is costly. Because of its great weight, it is difiicult to fabricate and handle. results in field distortions which may produce disturbances in the operation of the device. Field distortions may be particularly troublesome at the moment of electron injection when the timevarying field has just passed through a zero value.
  • An apparatus containing an iron core is limited to field values of a maximum of approximately 15,000 to 20,000 gauss.
  • an apparatus which comprises a modified accelerating structure having an air core, that is charged particles are caused to be accelerate-d therein without the emotion of iron core. It is desirable in such air core apparatus that the means whereby the magnetic accelerating field is generated should couple as closely as possible with the electron beam so that energy will not be stored in a greater volume of air than necessary. It is desirable that the magnetic field which is generated by this means should be relatively small at the electron orbit and that its variation with the radius should-be so small that it will not interfere with the guide field. These are contradictory conditions to be met by a single magnetic winding. An elongated coil will have a small external field but the coupling coefiicient will be low. A short coil will result in good coupling but the accelerating field at the orbit will be highly dependent on the radius.
  • a magnetic guide field and a magnetic time-varying field are generated by separate means.
  • One field-generating means generates a guide field which varies in a predetermined-relation with respect to the radius of the orbit of acceleration and another magnetic meansis provided to generate time-varying magnetic fields which so neutralize one another that they do not appreciably modify the magnetic guide field at the orbit of the accelerated electrons; the coupling of such
  • Fig. 1 is a diagram showing spatial relationships of magnetic fields
  • Fig. 2 is a graph of field distribution and magnitude
  • Fig. 3 shows in vertical section an accelerator having a plurality of correlated magnetic windings for generating magnetic fields for guiding and accelerating electrons
  • FIG. 4 shows a portion of the acceleration chamber which contains an electron gun for introducing electrons to be accelerated
  • Fig. 5 is a circuit connection diagram
  • Fig. 6 is a sectional plan view of an accelerating chamber which is equipped with means for supplemental high frequency acceleration
  • Fig. 7 is a graph showing diagrammatically the relation of cooperating accelerating fields in the latter device
  • Fig. 8 is a diagram of coil connections
  • Fig. 9 is an alternative circuit con-
  • a coil arrangement suitably applying the invention is shown diagrammatically in Fig. 1.
  • the point 0 represents the location of the orbit of electrons whose motion is to be controlled by the coil arrangement. It will be shown that by proper distribution and energization of the coils they can be caused both to accelerate and to guide electrons in the orbit O in a manner which fully realizes the objects previously set forth.
  • coils C1, C2 and D1, D2 which have the primary function of providing an accelerating flux within the electron orbit.
  • the field in their plane of symmetry can be calculated as :a function of radial distance from the axis of the coils and proves to have the form indicated by the graph R of Fig. 2. If taken with respect to the plane of symmetry, the field thus plotted will have an axial but no radial component.
  • the radius of the coils is so chosen that the minimum of the field pattern indicated at A lies at the radius of the electron orbit.
  • a second pair of coils D1 and D2 can be located such that the maximum field due to the coils D1, D2 will lie at over the minimum due to the coils C1, C2.
  • loci OF along Which this condition can be satisfied referring to Fig. 1, there exist loci OF along Which this condition can be satisfied. If now the ampere turns in the coils D1, D2 bear the right relation to the ampere turns in the coils C1, C2, the fields at 0 due to the two pairs of coils will cancel because of the establishment by the coils D1, D2 of the field having the distribution and magnitude indicated by the curve S of Fig. 2.
  • the first derivative of the field with radius also disappears at 0. If now the correct location on OF is chosen for the coils D1, D2, the second derivatives of the field may also be made to cancel. Under these conditions the field due to the four coils will be efiectively zero over a considerable region around the orbit. In practice, however, it may prove that exact cancellation of the second derivatives is not as desirable as an approximate matching of field characteristics which may give a field which is not zero but is small over a larger region. It is worthy of note that Maxwells equations insure that zero field over a range of radius in the plane of symmetry also results in low fields as one leaves the plane of symmetry in the axial direction.
  • FIG. 3 The application of a coil system such as that which has thus been described to a practical apparatus is illustrated in Fig. 3.
  • the apparatus shown in Fig, 3 comprises a frame 1 consisting of any suitable insulating material, such as wood,
  • annular evacuated accelerating chamber 2 Communicating with chamber 2 is a side chamber 3 into which are sealed conductors 4 (see Fig. 4) leading to an electron gun 5 whereby electrons to be accelerated are introduced into the annular chamber 2.
  • the chamber 2 is highly evacuated.
  • the coil system provided includes a coil pair l4, 15 which corresponds to the coils G1, G2 of Fig. l, a solenoidal coil l6 which corresponds to the coil H of Fig. 1, and coil pairs I8, l9 and 20, 2
  • An energizing circuit for use with the structure of Fig. 3 is shown diagrammatically in Fig. 5. It includes a pair of capacitors, or capacitor banks, 23 and 24 connected to the windings
  • the guide field will be essentially independent of the current flow in these coils. It may be desirable in order to minimize field variations due to the coil leads to subdivide the windings, as shown in Fig, 8, into several closely spaced sections connected in parallel, the leads l1, emerging as shown at spaced circumferential points.
  • the electrons so provided in the annular enclosure may be accelerated to an energy level on the order of several million electron volts provided proper balance exists between the guide field and accelerating flux as established by the various coils. As is well known from betatron theory, this balance requires that the following relationship "exist:
  • Average magnetic flux included within the orbit twice magnetic field at the orbit extended over the entire area enclosed by the orbital path.
  • the following cycle of operations occurs starting from the moment when the switch 30 of Fig. is closed. In. a few microseconds, when the magnetic field at the orbit has reached a value which will cause electrons of several kilovolts energy to be constrained to travel in the orbit afforded by the annular chamber, the electron gun 5 is automatically energized to inject electrons at such an energy level.
  • the electron gun may be operated for only a brief period or pulse of perhaps a few microseconds length.
  • the electrons which are thus introduced into the evacuated accelerating space are accelerated by the time varying magnetic flux within the orbit while being guided by the field at the orbit to a velocity equivalent to 2 or 3 million electron volts.
  • the chamber 2 may be provided with.
  • conducting coatings 6, l which are separated by insulating gaps 8, 9 across which high frequency fields may be set up.
  • Lead-in conductors i6, II which are illustrated conventionally are provided to supply high frequency potentials to the conducting coatings 6, 1 which constitute interior electrodes.
  • the curve V correspondingly represents the variation in the accelerating flux produced by the accelerating coils l8, l9 and 20, 21, it being 'noted that the resonant frequency of the flux producing circuit is, in this instance, made many times that of the guide field producing circuit.
  • This high frequency field may be initiated at a proper time in one way by a circuit arrangement such as that shown in Fig. 5 in which a high frequency source 36 is connected to the energizing circuit of the accelerating and guide field coils through a properly timed delay device 34 which is so adjusted as to assure the abrupt energization of the high frequency source at the time b (Fig. '7).
  • the high frequency source connects with conductors H], H which correspond to the similarly numbered conductors shown in Fig. 6.
  • De-energization of the high frequency source may be accomplished through a second delay device 3! (Fig. 5) which will act at a time c (Fig. 7) which is near the peak of the accelerating flux wave. This will permit the accelerated electrons to diverge from the accelerating orbit and to impinge upon a target placed outside the orbit.
  • the frequency of the field applied to the electrodes 6 and i must be correlated to the dimensions of the accelerating chamber 2. For an orbit radius of about 18 inches diameter, a frequency on the order of 200 megacycles is satisfactory.
  • the connections may be modified.
  • the windings l6, l9 and 20 may be connected in series to a capacitor bank 3%.
  • the windings l4, l5 and I6 are connected in series to a capacitor bank 46.
  • the capacitors 36, it are charged in series with a single impedance t l.
  • An air core electron accelerating apparatus comprising means providing a space for the gymtion of electrons in a generally circular orbit, means for introducing electrons into said space,
  • said guide field generating means comprising coils respectively located inside of and outside of the orbit and connected to cause their action to be cumulative at the orbit so as effectively to restrain said particles to said orbit, and said accelerating flux generating means comprising additional coils inside of and outside of the orbit and connected to cause their magnetic fields to be neutralizing at the orbit.
  • An air core electron accelerating apparatus comprising means providing a space for the gymtion of electrons in a generally circular orbit, means for introducing electrons into said space, means for generating a time-varying magnetic flux to accelerate said electrons in said orbit, and separate means for generating a time-varying magnetic guide field for maintaining said electrons in said orbit, said guide field generating means comprising coils respectively located inside of and outside of the orbit and connected to cause their action to be cumulative at the orbit so as effectively to restrain said particles to said orbit, and said accelerating flux-generating means comprising a pair of axially spaced coils inside of said orbit and a second pair of axially spaced coils outside of said orbit, the mutual spacing of the members of said coil pairs being effective to cause their magnetic fields at the orbit to be self-neutralizing.
  • Apparatus for accelerating charged parti cles along an orbital path comprising: air-cored guide field windings adjacent said path including first coils inside said path and second coils outside said path, said first and second coils being magnetically coupled to said path to produce conjointly a time-varying magnetic field which constrains said particles to said path; and aircored flux generating windings adjacent said guide field windings including coils inside said first coils and coils outside said second coils, said coils being magnetically coupled to said path to produce conjointly a time-varying magnetic flux which links said path to accelerate said particles but which exerts substantially no deflecting force upon said particles within said path.
  • Apparatus for accelerating charged particles along an orbital path comprising: air-cored guide field windings adjacent said path including first coils inside said path and second coils outside said path, said coils being magnetically coupled to said path to produce conjointly a timevarying magnetic field which constrains said particles to said path; and air-cored fiux generating windings adjacent said guide field windings including coils inside said first coils respectively axially spaced on opposite sides of a plane in which said orbit lies and coils outside said sec. ond coils respectively axially spaced on opposite sides of said plane, said last positively named coils being magnetically coupled to said path to produce conjointly a time-varying magnetic flux which links said path to accelerate said particles but which exerts substantially no deflecting force upon said particles within said path.
  • a source of voltage air-cored flux generating windings adjacent said path including first coils inside said path respectively axially spaced on opposite sides of a plane in which said orbit lies and second coils outside said path respectively axially spaced on opposite sides of said plane, all said coils being connected to said voltage source to produce conjointly a time-varying magnetic fiux which links said path to accelerate said particles during at least a portion of said predetermined cycle; and air-cored guide field generating windings including coils between said path and said first coils and coils between said path and said second coils, all said last positively named coils being connected to said voltage source to produce conjointly a timevarying magnetic field at said orbit to constrain said particles to said path during said predetermined cycle.
  • flux generating windings adjacent said path including first coils inside said path respectively axially spaced on opposite sides of a plane in which said orbit lies and second coils outside said path respectively axially spaced on opposite sides of said plane, the flux paths within said inner coils and between said inner and outer coils being substantially free of ferromagnetic material and all said coils being connected so that upon excitation of said apparatus current flow in them is in the same direction with respect to their common axis whereby their magnetic fields neutralize one another in the region of said orbital path; and additional windings in close proximity to said orbit for providing upon excitation of the apparatus a radially varying guide field to constrain said particles within said orbit.
  • a timevarying magnetic flux links said path to accelerate the particles while a time-varying magnetic guide field acts to restrain the particles to the path
  • the combination which includes a first pair of coils within said orbit axially spaced on opposite sides of a plane in which said orbit lies and enclosing a space substantially free of ferromagnetic material, and a second pair of coils outside said orbit axially spaced on opposite sides of said plane and enclosing a space substantially free of ferromagnetic material, both said pairs of coils being spatially interrelated to produce upon energization of said apparatus a combined magnetic field which is substantially zero in the region of said orbit while producing the timevarying magnetic fiux which links said orbit to accelerate the particles.

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Plasma & Fusion (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • Particle Accelerators (AREA)
US724066A 1947-01-24 1947-01-24 Accelerating apparatus for charged particles Expired - Lifetime US2465786A (en)

Priority Applications (9)

Application Number Priority Date Filing Date Title
BE479999D BE479999A (US08066781-20111129-C00013.png) 1947-01-24
BE507189D BE507189A (US08066781-20111129-C00013.png) 1947-01-24
FR962863D FR962863A (US08066781-20111129-C00013.png) 1947-01-24
US724066A US2465786A (en) 1947-01-24 1947-01-24 Accelerating apparatus for charged particles
GB2296/48A GB665828A (en) 1947-01-24 1948-01-26 Improvements in and relating to magnetic induction accelerating apparatus for charged particles
CH298296D CH298296A (de) 1947-01-24 1951-11-09 Apparat zur Beschleunigung von elektrisch geladenen Teilchen.
DEI4861A DE900853C (de) 1947-01-24 1951-11-14 Anordnung zur Beschleunigung geladener Teilchen
GB27086/51A GB711916A (en) 1947-01-24 1951-11-19 Improvements in and relating to apparatus for accelerating charged particles
FR62813D FR62813E (fr) 1947-01-24 1951-11-19 Accélérateur de particules chargées

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Application Number Priority Date Filing Date Title
US724066A US2465786A (en) 1947-01-24 1947-01-24 Accelerating apparatus for charged particles
US196482A US2622194A (en) 1950-11-18 1950-11-18 Apparatus for accelerating charged particles

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US2465786A true US2465786A (en) 1949-03-29

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US724066A Expired - Lifetime US2465786A (en) 1947-01-24 1947-01-24 Accelerating apparatus for charged particles

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US (1) US2465786A (US08066781-20111129-C00013.png)
BE (2) BE479999A (US08066781-20111129-C00013.png)
CH (1) CH298296A (US08066781-20111129-C00013.png)
DE (1) DE900853C (US08066781-20111129-C00013.png)
FR (2) FR62813E (US08066781-20111129-C00013.png)
GB (2) GB665828A (US08066781-20111129-C00013.png)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2576601A (en) * 1949-10-06 1951-11-27 Earl E Hays Method of accelerating ions
US2622194A (en) * 1950-11-18 1952-12-16 Gen Electric Apparatus for accelerating charged particles
US2675470A (en) * 1948-07-28 1954-04-13 Bbc Brown Boveri & Cie Electron accelerator
US2738420A (en) * 1950-12-28 1956-03-13 Gen Electric Injection into charged particle accelerators
US2829249A (en) * 1952-08-21 1958-04-01 Gen Electric Apparatus for accelerating charged particles
DE102007045495B4 (de) * 2006-09-26 2019-06-19 Mitsubishi Electric Corp. Kreisbeschleunigungsvorrichtung, Generator für elektromagnetische Wellen und elektromagnetische Wellen verwendendes Abbildungssystem

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CH380250A (de) * 1959-09-30 1964-07-31 Ceskoslovenska Akademie Ved Schaltungsanordnung zur Stabilisierung des Stromes eines Wechselstrommagneten, insbesondere eines Betatron- oder Synchrotronmagneten

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2103303A (en) * 1935-03-06 1937-12-28 Siemens Ag Device for producing electron rays of high energy

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2103303A (en) * 1935-03-06 1937-12-28 Siemens Ag Device for producing electron rays of high energy

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2675470A (en) * 1948-07-28 1954-04-13 Bbc Brown Boveri & Cie Electron accelerator
US2576601A (en) * 1949-10-06 1951-11-27 Earl E Hays Method of accelerating ions
US2622194A (en) * 1950-11-18 1952-12-16 Gen Electric Apparatus for accelerating charged particles
US2738420A (en) * 1950-12-28 1956-03-13 Gen Electric Injection into charged particle accelerators
US2829249A (en) * 1952-08-21 1958-04-01 Gen Electric Apparatus for accelerating charged particles
DE102007045495B4 (de) * 2006-09-26 2019-06-19 Mitsubishi Electric Corp. Kreisbeschleunigungsvorrichtung, Generator für elektromagnetische Wellen und elektromagnetische Wellen verwendendes Abbildungssystem

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Publication number Publication date
CH298296A (de) 1954-04-30
BE507189A (US08066781-20111129-C00013.png)
DE900853C (de) 1954-01-04
BE479999A (US08066781-20111129-C00013.png)
GB711916A (en) 1954-07-14
FR62813E (fr) 1955-06-24
FR962863A (US08066781-20111129-C00013.png) 1950-06-22
GB665828A (en) 1952-01-30

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