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US2631234A - Magnetic induction accelerator - Google Patents

Magnetic induction accelerator Download PDF

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Publication number
US2631234A
US2631234A US793068A US79306847A US2631234A US 2631234 A US2631234 A US 2631234A US 793068 A US793068 A US 793068A US 79306847 A US79306847 A US 79306847A US 2631234 A US2631234 A US 2631234A
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US
United States
Prior art keywords
cathode
electrode
electron
stream
electrons
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Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US793068A
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English (en)
Inventor
Wideroe Rolf
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
BBC Brown Boveri AG Germany
Original Assignee
Bbc Brown Boveri & Cie
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Publication date
Application filed by Bbc Brown Boveri & Cie filed Critical Bbc Brown Boveri & Cie
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Publication of US2631234A publication Critical patent/US2631234A/en
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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

  • Fig..- 1- is a; view indiametricali section of induction. type electron accelerator provided with a conventional: type of electron injector;
  • Fig.- 2 is ahorizontal sectional view of the electron injector: shown in Fig. 1 but drawn to an enlarged scale;
  • Fig. 3- is a sectional view similar to'Fig. 2- illustrating the improved type of electron injector device embodyingv the principles of; theinvention;
  • Fig. 311 is a sectional view similar to- Fig. 3 shewingi'a slight modification of: the Fig. 3: arrangement;
  • Fig. 4 is aperspective: of the electron injector illustrated in Fig.v 3;
  • FIG. 5' is a: sectional view of: a somewhat difierent embodiment: of the invention particu.-'- larly' adapted f-o'r'use withinduction. type acceler'ators where-successive streams of electrons are accelerated inopp'osite directionsalong the orbit on opposite halves. of the alternating; current. which produces the magnetic field;
  • Fig. 6 is a 2: View in perspective of the electron injector' accordingto" Fig 5"; and
  • Figs: 7-11 are sectibna-l views similar to Fig- 3" illustrating several other modified embodiments of the latterpos'sible' within'the scope of the invention;
  • Poles" fl-l l" and 3--I3"' are surrounded by an annular winding preferably split into" two coil” sections l6*-l 6" connected in series for energi'zation from a" source of altern'ating current of suitable frequency as for example 10'0" cycles/sec. applied to terminals l'l'.
  • An annular. evacuated glass tube I 8 rests-in the air. gap [.4 between poles" l3-'t3" and thereby surrounds'the axial poles I l-l-l-.
  • Located within the tube I8 is an'electron emi'ssiVe cathode 2 0 the axis of which is arranged parallel to the axis a-a'.' Cathode 2i)" is placed within a" semicylindrical shaped" focus'sing electrode (Wehencountered properly guiding; the electron stream. into the. equilibrium circle 231' from the cathode 20.
  • emi'ssiVe cathode 2 0 the axis of which is arranged parallel to the axis a-a'.
  • Cathode 2i) is placed within a" semicylindrical shaped" focus'sing electrode (Wehencountered properly guiding; the electron stream. into the. equilibrium circle 231'
  • the single accelerating electrode 22 of Figs. 1 and 2 is replaced by separate electrodes (i. e. electrically independent) each being charged to a different potential.
  • One of these electrodes is located to one side of the cathode between the latter and the equilib rium circle and is given a potential that is positive with respect to the cathode; the other elecr trode being located at the opposite side of the cathode is given a different positive potential for instance greater than that of the aforementioned first electrode with respect to the cathode.
  • the accelerating electrode structure is comprised of a pair of parallel rectangular plates 26, 21 located on each side of the Wehnelt cylinder 2
  • cathode 20 can for instance be placed at'l0 kilovolts
  • electrostatic field produced between the plates 26, 2'! by the different potentials impressed upon them will then be such as to cause the electron stream to be deflected radially outward i. e. in the direction of arrow 28. borhood of the cathode 20, this field is distorted In the direct neighand on the electron emissive surface 20 itself the field is equal to zero. The force produced by the electric field between plates 26, 21 thus increases from zero at the cathode 20 in the direction of stream emission until a maximum value is reached.
  • This radially outward directed force accordingly follows a law similar to that followed by the radially inward directed Lorenz force of the guide field which likewise begins to increase at the instant 'of electron emission, the velocity v in Equation 1 of the emitted electrons being very small at the surface of the cathode, and is therefore effective to prevent the electron stream from taking an initial path of the wrong curvature as already explained.
  • the two forces generally compensate one another with the result that the electron stream leaves the space between plates 26, 2'! on an inward spiral path such as indicated by the curve 29 that will assure a clear and uninterrupted run into the equilibrium circle after a few turns around the tube l8.
  • a pair of juxtaposed curved electrodes 26', 21' may be employed as shown in Fig. 3a.
  • induction accelerator be of the type such as shown in my co-pending United States application, Ser. No. 720,544 filed January '7,
  • the compensating electrostatic field produced between plates 26 and 21 may be varied either by changing the radial distances 0 and d between the plates and the cathode or by chang ing the contour of the plates as shown in Figs. '7 to 11 or by using both of these expedients to suit particular operating conditions encountered.
  • , 32 are each provided with an outwardly bent portion 3
  • the electrode located at the side'of the cathode nearestthe equilibrium circle is a rectangular plane plate 34 while the other plate is curved or bent to alter the strength of the electrostatic field at successive points along the path taken by the stream as it passes between the plates.
  • the outer plate 35 has an outwardly bent plane wall section 35a beginning at the radius passing through the cathode 28 and the axis a-a.
  • the Fig. 9 construction is similar to that shown in Fig. 8 except that the bent portion 36a of the plate 36 s is offset radially inward and begins at a point immediately in front of the mouth of electrode 2 In Figs.
  • the outer electrode plate has a portion which arches inwardly towards the stream beginning at a point located substantially at the mouth of electrode 2
  • the curved portion 31a of the outer plate 31 conf-ormsto the arc of a relatively large circle while in Fig. 11, the
  • curved plate portion 38a of electrode 38 follows the arc of a circle of much smaller radius.
  • the two halves of the accelerating electrode such as the plates 26, 21 in Figs. 3 and 4 can also be used for imparting to the electron stream an initial radial speed component so that in the event the position of the cathode in a radial direction is not exactly correct with respect to the induction and control field structure, the stream will still be guided into the equilibrium circle along a satisfactory inwardly spiraling path.
  • the potential applied to at least plate 2! is made adjustable such as by rheostat 39 so that it can be set to the value best suited for a particular operating condition of the accelerator.
  • a magnetic induction accelerator for charged particles such as electrons including an annular chamber in which the electrons are accelerated to high velocity along a circle of equilibrium under the combined action of a magnetic inducing field and a magnetic control field whose respective field strengths vary with time and an electron emissive cathode located within said chamber to one side of said circle and from which electron streams are periodically emitted in timed relation with the variation in said fields, of electrode means for imparting an initial velocity to the electron stream, said electrode means being comprised of a pair of electrically independent electrode members located on each side of said cathode and which when charged establish therebetween an electrostatic field through which th electron stream passes en route to the equilibrium circle, and a charging input line individual to each of said electrode members, said electrode member nearest said circle being adapted to be charged through its associated input line to a potential positive in relation to that of the cathode and said other electrode member being adapted to be charged through its associated input line .to a different positive potential in relation to that of the cathode.
  • a magnetic induction accelerator as defined in claim 1 wherein the spacing between said electrode members varies in a direction substantially transverse to the emission path of the electron stream.
  • An accelerator for electrons comprising the combination of an annular evacuated tube providing a path for the acceleration of electrons, means for providing a time-varying magnetic field for causing acceleration of electrons in said tube, an electron source, means for projecting electrons from said source into said field and an electrode located adjacent the emergence of said electrons for guiding said electrons into a direction substantially parallel to the orbital path of said electrons in said tube.

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Plasma & Fusion (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • Particle Accelerators (AREA)
US793068A 1944-11-20 1947-12-22 Magnetic induction accelerator Expired - Lifetime US2631234A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE260726X 1944-11-20

Publications (1)

Publication Number Publication Date
US2631234A true US2631234A (en) 1953-03-10

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Application Number Title Priority Date Filing Date
US793068A Expired - Lifetime US2631234A (en) 1944-11-20 1947-12-22 Magnetic induction accelerator

Country Status (5)

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US (1) US2631234A (xx)
CH (1) CH260726A (xx)
FR (1) FR956809A (xx)
GB (1) GB658255A (xx)
NL (1) NL68946C (xx)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4543509A (en) * 1982-12-23 1985-09-24 Atomic Energy Of Canada Limited Off-axis electron gun
US20090267543A1 (en) * 2006-10-28 2009-10-29 Bermuth Joerg Betatron with a removable accelerator block
US20090267542A1 (en) * 2006-10-28 2009-10-29 Bermuth Joerg Betatron with a variable orbit radius

Citations (3)

* 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
US2394073A (en) * 1943-09-10 1946-02-05 Gen Electric Electron accelerator
US2484549A (en) * 1947-07-30 1949-10-11 Gen Electric Electron injection apparatus

Patent Citations (3)

* 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
US2394073A (en) * 1943-09-10 1946-02-05 Gen Electric Electron accelerator
US2484549A (en) * 1947-07-30 1949-10-11 Gen Electric Electron injection apparatus

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4543509A (en) * 1982-12-23 1985-09-24 Atomic Energy Of Canada Limited Off-axis electron gun
US20090267543A1 (en) * 2006-10-28 2009-10-29 Bermuth Joerg Betatron with a removable accelerator block
US20090267542A1 (en) * 2006-10-28 2009-10-29 Bermuth Joerg Betatron with a variable orbit radius
US7994740B2 (en) * 2006-10-28 2011-08-09 Smiths Heimann Gmbh Betatron with a removable accelerator block
US8013546B2 (en) * 2006-10-28 2011-09-06 Smiths Heimann Gmbh Betatron with a variable orbit radius

Also Published As

Publication number Publication date
CH260726A (de) 1949-03-31
NL68946C (xx)
FR956809A (xx) 1950-02-08
GB658255A (en) 1951-10-03

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