US2617026A - Induction accelerator for electrons - Google Patents

Induction accelerator for electrons Download PDF

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Publication number
US2617026A
US2617026A US111839A US11183949A US2617026A US 2617026 A US2617026 A US 2617026A US 111839 A US111839 A US 111839A US 11183949 A US11183949 A US 11183949A US 2617026 A US2617026 A US 2617026A
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United States
Prior art keywords
path
electron
electrons
core
field
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Expired - Lifetime
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US111839A
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English (en)
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Bierman Aron
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Hartford National Bank and Trust Co
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Hartford National Bank and Trust Co
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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

Definitions

  • Induction accelerators for electrons generally comprise a substantially wholly closed iron circult for the magnetic power flux which is produced by coils carrying a low-frequency alternating current.
  • electrons are accelerated in an annular path by means of the electric power generated in this path by the field strength of the magnetic field which is variable with time.
  • the iron body comprising the yoke and the pole-shoes and serving for generating the magnetic flux is a considerable weight. Consequently, it has been suggested to make the device smaller, lighter and cheaper by omitting the llOll.
  • the electrons may describe a circular path, not only an accelerating field but also a magnetic control field is required.
  • the lines of force of the accelerating field are circumscribed by the electron path and those of the control field are intersected thereby. It is necessary that the field strength at the electron path should be half that which would occur throughout the surface circumscribed by the path if the central fiux were evenly distributed over this surface.
  • the central field is too weak to satisfy this condition.
  • this disadvantage is obviated by the provision in addition to the two coils arranged on each side of the discharge tube of a central coil surrounded by the annular discharge tube which is traversed by the electric load as well as the two coils arranged laterally of the tube.
  • a further means of obtaining the required contraction or expansion of the electron path is used in apparatus comprising a magnetic circuit constituted by an iron body.
  • apparatus comprising a magnetic circuit constituted by an iron body.
  • centre of the iron of the magnetic circuit is saturated earlier than the part in the vicinity of the electron path since the field is materially stronger at the centre.
  • auxiliary poles to modify the magnetic field in the vicinity of an electron path, in which the magnetic circuit of this control field is constructed with a portion having a smaller crosssectional area so that, upon increase of the field during the acceleration period, saturation occurs in this portion earlier than in the central core.
  • the present invention relates to such apparatus in which the magnetic circuit fundamentally comprises so little iron that the high-frequency oscillation of an electric load is required to enable magnetic fields of sufiicient strength to be generated.
  • the magnetic circuit fundamentally comprises so little iron that the high-frequency oscillation of an electric load is required to enable magnetic fields of sufiicient strength to be generated.
  • the invention instead of utilising a central coil, use is made of an open iron core, hence a core which extends not farther than is necessary for concentrating the central flux within the zone circumscribed by the discharge tube. It has been found possible with the use of the said core to fulfill the requirement concerning the ratio between the actual fiux and that of a homogeneously imagined field and to proportion the sectional area of the core in such manner that this ratio is disturbed at the end of the acceleration period as a result of saturation -of the core.
  • the proper ratio between the total flux and the field strength at the electron path is adjustable in a simple manner by providing an adjustable air-gap, in which event the core may consist of two portions which are relatively slidable.
  • the total flux decreases when the parts of the core are moved away from one another.
  • the presence of an air-gar) at the centre of the core located in the plane of the electron path furthermore favourably affects the configuration 3 of the magnetic control-field within the tube.
  • the so-called flux condition must be fulfilled, owing to which the electrons describe a circular path, it is of importance that electrons diverging from this path due to some reason or other, for example impact with gas molecules, should return to the path by the action of the magnetic directional field.
  • the magnetic field strength in the vicinity of the electron path is required to be proportional to r", I being theradius of the path and n a figure between 0 and 1.
  • the radial stability in the vicinity of the electron path is different from that at the path which the electrons have to follow, which results in the dimensions of the beam not being in conformityw-ith the choice of the ratio between the axial and the radial stability in the electron path. This may lead to a loss of electrons which, as a result of disturbing influences, diverge from the path of the beam to a greater extent than would otherwise be the case.
  • an air-gap is provided at the centre of the core, the stray field produced at this areamay serve to correct the configuration of the field within the tube.
  • the air-gap may be so adjusted so that n has a constant value over a suificiently' wide range.
  • Variation of the air-gap also varies the central flux so that th flux condition is affected.
  • one or more further air-gaps may be provided to permit of controlling the value of the flux and which are located at such a distance from the plane of the electron path as to act no longer upon the configuration of the magnetic field within the tube.
  • Fig. 1 shows a schematic representation of one embodiment of an induction accelerator accord-
  • the induction accelerator shown in Fig. 1 comprises a closed annular vessel I forming a discharge path for electrons emitted by a cathode 2 forming part of an electron gun 3.
  • the electrons are accelerated in an orbital path in the vessel by a pair of coaxial field coils 4 and 5 which are coaxial with the axis of the discharge vessel and are excited by a generator of electrical oscillations I3.
  • the flux generated by the coils traverses the path of the electron stream in the discharge vessel and the ratio of total flux to field strength at the. electron path, in. order to satisfy the condition that the magnetic: field strength in the vicinity of the electron path is proportional to r-, 1' being the radius of the path and n a figure between 0 and 1, is adjustable by providing a core 5, 1 coaxial with the coils having an adjustable air-gap.
  • the core shown in Fig. 1 is of the yokeless type and comprises two sections 6 and I which are separated by the air-gap but not joined by a yoke. By moving either or both sections of the core, th air-gap distance can be adjusted so that n has a constant value over a sufiiciently wide range.
  • the arrangement shown in Fig. 2 is similar to that shown in Fig. 1 except that the core comprises several. disconnected separate sections, 9, [0, II and 12 the central sections 9 and 10 being separated by an air-gap for determining the value of n. Thaadditional air-gaps afiorded by further dividing the core into a plurality of sections permits' greater control of the flux traversing the discharge path.
  • An electron induction accelerator comprising a closed vessel defining an annular discharge path, means including a cathode in said vessel for producing an electron stream in said vessel, and magnetic field producing means outside said vessel comprising a set of axially aligned opposed coils disposed on opposite sides of the discharge path and coaxial with the central axis of said discharge path, means connected to said coils to excite said coils for producing a time varying magnetic field, and an axially extending yokeiess core of magnetic material disposed between said coils and extending axially through said discharge path, said core having a cross-sectional area at which saturation of the core results at the end of the acceleration period of electrons in the discharge tube.
  • An electron induction accelerator as claimed in claim 1 in which the core comprises two separate and disconnected sections separated by an air-gap in the plane passing through the electron discharge path.
  • An electron induction accelerator as claimed in claim 1 in which the core comprises a plurality of separate disconnected sections separated by air-gaps spaced at a distance from the plane of the electron discharge path at which the configuration of the magnetic field within the vessel is substantially unafiected.

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Plasma & Fusion (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • Particle Accelerators (AREA)
US111839A 1948-08-27 1949-08-23 Induction accelerator for electrons Expired - Lifetime US2617026A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
NL278753X 1948-08-27

Publications (1)

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US2617026A true US2617026A (en) 1952-11-04

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US111839A Expired - Lifetime US2617026A (en) 1948-08-27 1949-08-23 Induction accelerator for electrons

Country Status (7)

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US (1) US2617026A (en, 2012)
BE (1) BE490815A (en, 2012)
CH (1) CH278753A (en, 2012)
DE (1) DE810886C (en, 2012)
FR (1) FR993767A (en, 2012)
GB (1) GB680008A (en, 2012)
NL (1) NL72343C (en, 2012)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2964627A (en) * 1957-07-01 1960-12-13 Trub Tauber & Co A G Double-focussing spectrometer for electrically charged particles
US20030048053A1 (en) * 2000-03-22 2003-03-13 Gunter Kornfeld Plasma accelerator arrangement

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1137964A (en) * 1913-04-26 1915-05-04 Robert H Goddard Method of and means for producing electrically-charged particles.
US2103303A (en) * 1935-03-06 1937-12-28 Siemens Ag Device for producing electron rays of high energy
US2191594A (en) * 1938-02-05 1940-02-27 Raytheon Mfg Co Controlled gaseous discharge device
US2297305A (en) * 1940-11-13 1942-09-29 Gen Electric Magnetic induction accelerator

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1137964A (en) * 1913-04-26 1915-05-04 Robert H Goddard Method of and means for producing electrically-charged particles.
US2103303A (en) * 1935-03-06 1937-12-28 Siemens Ag Device for producing electron rays of high energy
US2191594A (en) * 1938-02-05 1940-02-27 Raytheon Mfg Co Controlled gaseous discharge device
US2297305A (en) * 1940-11-13 1942-09-29 Gen Electric Magnetic induction accelerator

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2964627A (en) * 1957-07-01 1960-12-13 Trub Tauber & Co A G Double-focussing spectrometer for electrically charged particles
US20030048053A1 (en) * 2000-03-22 2003-03-13 Gunter Kornfeld Plasma accelerator arrangement
US6803705B2 (en) * 2000-03-22 2004-10-12 Thales Electron Devices Gmbh Plasma accelerator arrangement

Also Published As

Publication number Publication date
BE490815A (en, 2012)
FR993767A (fr) 1951-11-07
DE810886C (de) 1951-08-13
NL72343C (en, 2012)
CH278753A (de) 1951-10-31
GB680008A (en) 1952-10-01

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