US3056069A - Variable induction magnets of the type used in synchrotrons - Google Patents

Variable induction magnets of the type used in synchrotrons Download PDF

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Publication number
US3056069A
US3056069A US665064A US66506457A US3056069A US 3056069 A US3056069 A US 3056069A US 665064 A US665064 A US 665064A US 66506457 A US66506457 A US 66506457A US 3056069 A US3056069 A US 3056069A
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Prior art keywords
induction
correction
curve
zone
index
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US665064A
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English (en)
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Parain Jacques
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Commissariat a lEnergie Atomique et aux Energies Alternatives CEA
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Commissariat a lEnergie Atomique CEA
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H33/00—High-tension or heavy-current switches with arc-extinguishing or arc-preventing means
    • H01H33/02—Details
    • H01H33/44—Devices for ensuring operation of the switch at a predetermined point in the AC cycle
    • 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
    • H05H7/04—Magnet systems, e.g. undulators, wigglers; Energisation thereof

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  • the object of this invention is to provide a magnet of this type in which the deformations of the field in the air gap due to magnetic saturation under the effect of high induction are corrected in a simple and efficient manner.
  • the essential feature of this invention consists in the fact that, in the portion of at least one of the pole pieces of the magnet Which is adjoining the air gap, there is provided a Zone the permeability of which is different from that of the material which constitutes the remainder of said pole piece, and is lower than it, so as automatically to correct at least partly the deformations of the magnetic modified for relatively low values of the induction.
  • index of the magnetic field will be used to designate the quantity:
  • the induction in the air gap may generally vary from 300 to 15,000 gausses for instance, it is not possible to avoid, for values of the induction above approximately 10,000 gausses, a saturation of the magnetic circuit of the magnet (yoke and pole pieces) which deteriorates the and leads to a substantial increase of index n.
  • FIG. 1 is a diagrammatic sectional view of a magnet including yoke 1, pole pieces 2 and 3 removably fixed on said yoke and excitation windings 4 and 5.
  • the faces 6 and 7 of pole pieces 2 and 3 are equipotential surfaces of the mag the induction gradually faces of the pole pieces; they become oblique thereto, as shown at 8 and 9, which has for its effect to modify the field in the air gap in an undesirable manner.
  • the curves of FIG. 2 illustrate the modification of the field in the air gap of a synchrotron magnet.
  • Zthevalues of the index n of the field are plotted along the ordinates, and for points of the air gap the positions of which, with respect to the pole pieces, are plotted along the abscissa.
  • R is the radius of the stable orbit, the radii increasing from left to right in the direction of arrow R.
  • FIG. 2 shows curves 10, 11, 12, 13, 14 and 15 representing the variations of the field index n at different points of the air gap for the following values of the induction B Curve 10-from 3,000 to 7,000 gausses, Curve 11 l0,000 gausses,
  • n is due to the fact that the difference of consumption of ampere-turns in the yoke along two induction lines of different total lengths, such as 16 and 17 on FIG. 1, has a greater influence for high values of the induction.
  • this correction zone and the permeability of this zone are determined in accordance with the desired chart of the field to be obtained.
  • Correction of the defects of the field index for high values of the induction by creating a correction zone in the pole piece therefore permits of eliminating the drawbacks of correcting windings and of increasing the potentialities of a magnet intended to work with a variable induction (synchrotron or mass separator magnet for instance).
  • the defects of the magnet resulting from magnetic saturation may thus be corrected according to the invention in two difierent manners, corresponding to two different causes;
  • FIGS. 4 and 5 are diagrammatic cross sections of pole pieces made according to the invention to correct the two above mentioned defects respectively.
  • FIGS. 6 and 7 on the one hand, and FIGS. 8 and 9, on the other hand, give curves showing the influence upon induction B and index n of the correction zones illustr-ated by FIGS. 4 and 5 respectively.
  • FIG. 10 is a part perspective view of the suriace of a pole piece, provided with notches, made according to my invention, said pole piece being intended to be used in a synchrotron.
  • FIG. 11 shows curves giving the equivalent permeability p. of the correction zone as a function of the induction B and of the dimensions of the above mentioned notches.
  • FIG. 12 shows curves giving function of the same parameters.
  • FIG. 13 shows curves giving the values of index n as a function of the radius R in the air gap.
  • FIGS. 14 and 15 diagrammatically illustrate modifications of the correction zone according to my invention.
  • the correction zones and 21 are of varying thickness from one edge to the other of the air gap so as to compensate for the increase of the field due to saturation of the whole of the magnetic circuit.
  • FIG. 5 shows correction zones 26 and 27 of uniform thickness used to compensate for the effect of the saturation of the pole piece horns 22, 23, 24 and 25.
  • FIG. 6 shows curves obtained by plotting in ordinates the induction in the air gap at different points and in abscissas the radial distances of said points.
  • FIG. 7 the field index in the air gap is plotted in ordinates and the radial distances in abscissas.
  • curve 28 shows the initial induction (B (the magnetic circuit being unsaturated) and curve 29 shows the maximum induction (B (the magnetic circuit being saturated); the values of the induction are measured with units equal to B
  • the curve 30 is obtained after correction, which curve is substantially the same for all values of induction B
  • the cross-hatched area clearly shows the effect of the correction zone of variable height.
  • FIG. 6 also shows that, in the central portion of the pole piece where curves 28 and 30 are substantially rectilinear, said curves have the same slope which means that index n, according to the invention, has been kept practically constant for the whole range of variations of the induction, that is to say from (B to o)m- FIG.
  • FIG. 7 shows straight lines 31 and 32 which respectively represent the values of index n for inductions equal respectively to (B and (B when there is no correction zone; the difference between these two values of index n is equal to the above defined quantity An.
  • the field index n remains at its initial value (curve 31) for all values of the induction, even (B
  • FIG. 8 shows curves where the induction in the air gap has been plotted in ordinates and the radial distances in abscissas.
  • FIG. 9 shows in ordinates the field index in the air gap and in abscissas the radial distance.
  • Curve 34 is substantially a parabola, and consequently curve 36 of FIG. 9 which represents, for induction (B,,),,,, the variations of index n as a function of radius R, is practically a straight line.
  • An will designate the variations, measured at the limit of the useful zone having a half length equal to r, of the field index n due only to saturation of the pole piece horns (FIG. 9).
  • Angle Afi must of course be of a direction such that it produces a correction zone opposed to the defect to be corrected.
  • Arugu D in which: ,u is the value of the permeability in the yoke, D is a constant for a given magnet.
  • Formula III becomes r (FIG. 5) being the half width of the useful zone and 0 (FIG. 4) the half width of the correction zone of variable thickness.
  • This Formula V gives a thickness Ah which is always very small.
  • FIGS. 10 to illustrate different embodiments of the present invention as applied to variable induction magnets of the type used in synchrotrons.
  • the correction zone consists partly of iron and partly of air so as to comply with condition (H).
  • condition (H) For this purpose, notches are provided in pole piece 37 by juxtaposing metal sheets of different outlines, 38 being the initial outline of the pole piece.
  • B is chosen at will so that, knowing the curve F (B for the iron that is used, first and then ,u' are deduced by means of Formula VI.
  • Formula VII then gives B so that one point of the curve of FIG. 11 is obtained.
  • Curves 48, 49, 50, 51, 52 and 53 of FIG. 13 represent, in an improved magnet according to the invention, the variations of index n as a function of the radius for the same values of the induction as in FIG. 2 (that is to say respectively from 3,000 to 7,000 gausses, and for 10,000, 12,000, 13,000, 14,000 and 15,000 gausses) and show by comparison with said FIG. 2. the efficiency of the correction zone thus obtained.
  • pole piece 54 is divided into three elementary portions 55, 56 and 57 for each of which the index variation An and the corresponding angle A13 have been determined by means of the above Formula I.
  • the correction instead of being obtained by providing radial notches, might be achieved by making use of different geometrical arrangements (holes transverse grooves in the pole piece) or by making use of a homogeneous material such as a sintered alloy.
  • the correction zone would consist of a plate 58 (FIG. 15) fixed on the pole piece.
  • the defects due to the remanant field may also be corrected by a correction zone according to the invention.
  • a variable induction magnet of the type for establishing inductions varying from very high values, close to iron saturation value, to
  • a substantially annular yoke of magnetic material having said axis as a center and a substantially C-shaped cross section along its annular length
  • annular pole pieces in opposed face to face relationship terminating the ends of said yoke and having substantially parallel surfaces defining an air gap therebetween in which the orbit of said particles falls,
  • annular correction zone substantially co-extensive with at least one of said pole pieces of a magnetic permeability lower than that of the material of which the remainder of said yoke is made
  • annular correction Zone partially defined by an annular inner edge closest to said axis
  • the thickness of said correction zone defined by one 6 is said angle; E is the distance between said parallel surfaces; R is the radius between said axis and said orbit; and being the permeability of the material of which said correction zone is made; and
  • B is the value of the magnetic field along said orbit
  • 1 dR is the derivative of the magnetic field value with the orbit radius

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Optics & Photonics (AREA)
  • Plasma & Fusion (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • Power Engineering (AREA)
  • Particle Accelerators (AREA)
US665064A 1940-12-23 1957-06-11 Variable induction magnets of the type used in synchrotrons Expired - Lifetime US3056069A (en)

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FR1152327T 1940-12-23

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BE (1) BE558121A (en))
CH (1) CH345953A (en))
DE (1) DE1036418B (en))
FR (1) FR1152327A (en))
GB (1) GB845668A (en))
LU (1) LU35195A1 (en))
NL (1) NL104421C (en))

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3175131A (en) * 1961-02-08 1965-03-23 Richard J Burleigh Magnet construction for a variable energy cyclotron
US3225270A (en) * 1962-04-16 1965-12-21 Philips Corp Pole shoe assembly for a cyclotron electromagnet
US3417280A (en) * 1966-03-31 1968-12-17 Csf Traveling wave time delay device having a magnetic field in the drift region different from that in the delay line regions
US3459205A (en) * 1965-06-28 1969-08-05 Electro Optical Systems Inc Magnetically controlled fluid amplifier

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102008047197B4 (de) * 2008-09-15 2013-01-17 Bernhard Franczak Verfahren zur Strahlentherapie mit Ionenstrahlen und Teilchenbeschleuniger zur Durchführung des Verfahrens

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2297305A (en) * 1940-11-13 1942-09-29 Gen Electric Magnetic induction accelerator
US2394070A (en) * 1942-06-02 1946-02-05 Gen Electric Magnetic induction accelerator
CA492901A (en) * 1953-05-12 Goldman Jacob Electromagnet
DE938085C (de) * 1943-09-01 1956-01-19 Brown Ag Strahlentransformator
US2777099A (en) * 1955-08-26 1957-01-08 Martyn H Foss Pole structure of magnets

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CA492901A (en) * 1953-05-12 Goldman Jacob Electromagnet
US2297305A (en) * 1940-11-13 1942-09-29 Gen Electric Magnetic induction accelerator
US2394070A (en) * 1942-06-02 1946-02-05 Gen Electric Magnetic induction accelerator
DE938085C (de) * 1943-09-01 1956-01-19 Brown Ag Strahlentransformator
US2777099A (en) * 1955-08-26 1957-01-08 Martyn H Foss Pole structure of magnets

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3175131A (en) * 1961-02-08 1965-03-23 Richard J Burleigh Magnet construction for a variable energy cyclotron
US3225270A (en) * 1962-04-16 1965-12-21 Philips Corp Pole shoe assembly for a cyclotron electromagnet
US3459205A (en) * 1965-06-28 1969-08-05 Electro Optical Systems Inc Magnetically controlled fluid amplifier
US3417280A (en) * 1966-03-31 1968-12-17 Csf Traveling wave time delay device having a magnetic field in the drift region different from that in the delay line regions

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BE558121A (en))
FR1152327A (fr) 1958-02-14
CH345953A (fr) 1960-04-30
DE1036418B (de) 1958-08-14
NL104421C (en))
GB845668A (en) 1960-08-24
LU35195A1 (en))

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