JPH04273409A - Superconducting magnet device; particle accelerator using said superconducting magnet device - Google Patents

Abstract

PURPOSE:To correct an unmatched magnetic field generated when the side of a superconducting coil is displaced due to an electromagnetic force at a superconducting magnet device in which an opening has been formed on the outer circumferential side of the superconducting coil. CONSTITUTION:At a superconducting magnet device, one pair of superconducting coils 4, 5 which have been wound to be a fan shape are arranged so as to be faced on both faces of a particle circulation passage 2, and openings such as synchrotron radiation conducting ports 3a, 6a are installed at the outer circumferential side of the particle circulation passage. At the magnet device, displacement-correcting coils 9, 10 are wound so as to be adjacent to both side faces of coil sides situated on the opening side of the superconducting coils 4, 5, a compensation electric current flowing to the displacement-correcting coils 9, 10 is controlled and said unmatched magnetic field is corrected.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] The present invention relates to a superconducting magnet device and a particle accelerator using the superconducting magnet, and in particular to a superconducting magnet suitable as a fan-shaped superconducting deflection magnet for a particle accelerator such as a particle storage ring for synchrotron radiation generation. Concerning correction of irregular magnetic fields in devices.

0002

2. Description of the Related Art In a fan-shaped superconducting deflection magnet having an opening for leading out synchrotron radiation on its outer periphery, the superconducting coil is displaced by electromagnetic force generated by a current flowing through the superconducting coil, and an asymmetric magnetic field is generated.

[0003] Magnetic field correction technology for superconducting deflection magnets has been developed by IEEE Transactions on Magnetics (IEEE Tran
17, No. 1, 1981, pp. 728-731.
Lines and Accelerator Atsut
KEK” (Development of su
perconducting magnets f
or bean lines and acc
It is disclosed under the title ELERATORAT KEK). In this superconducting magnet, the cross-sectional shape of the superconducting coil in a cross section perpendicular to the charged particle trajectory is an aggregate shape of a plurality of superconductors arranged concentrically around the charged particle trajectory and symmetrically with respect to the central horizontal plane, and is in the form of a sheet. In this configuration, a plurality of magnetic field correction coils wound around the superconducting coil are arranged in the vicinity of the inner peripheral surface of the superconducting coil so as to be symmetrical with respect to a center horizontal plane and on a concentric circle centered on a charged particle trajectory.

However, in a structure in which an opening for leading out synchrotron radiation is provided on the outer circumferential side of a superconducting coil, such as in a fan-shaped superconducting deflection magnet of a particle storage ring for generating synchrotron radiation, a sheet-shaped magnetic field correction coil is used. Therefore, it is desired that other effective means for correcting the irregular magnetic field be developed.

[0005]

SUMMARY OF THE INVENTION Therefore, it is an object of the present invention to provide a superconducting magnet device having an opening on the outer circumferential side of a superconducting coil, such as a fan-shaped superconducting deflection magnet of a particle storage ring for synchrotron radiation generation. An object of the present invention is to provide a correcting means suitable for correcting an irregular magnetic field generated when a side of the superconducting coil is displaced by electromagnetic force caused by a current flowing through the superconducting coil.

[0006]

[Means for Solving the Problems] The present invention provides a pair of superconducting coils wound in a fan shape, which are arranged facing each other at a predetermined interval on both sides of a particle circulation passage, and an opening is provided on the outer circumferential side of the particle circulation passage. A superconducting magnet device comprising: a displacement correction coil wound adjacent to both sides of the coil side located on the opening side of the superconducting coil; and a compensation current control device for controlling a compensation current flowing through the displacement correction coil. It is characterized by having been established.

[0007]

[Operation] The current flowing through the displacement correction coil corrects the generation of an irregular magnetic field caused by the displacement of the sides of the superconducting coil due to the electromagnetic force caused by the current flowing through the superconducting coil.

[0008]

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a plan view of a fan-shaped superconducting deflection magnet device constituting an electron storage ring for synchrotron radiation generation, FIG. 2 is a sectional view taken along line II--II, and FIG. 3 is an electrical connection diagram.

The superconducting deflection magnet 1 deflects charged particles (electrons) orbiting in a particle orbit 2. One deflection magnet 1 takes charge of 90 degree deflection, and four deflection magnets 1 deflect charged particles (electrons) orbiting around the particle orbit 2. Configure a storage ring.

[0011] The iron core 3 of the superconducting magnet 1 has a planar shape that is approximately 90 degrees fan-shaped, and its vertical cross-section has a donut (arc) shaped space 3 in the center for arranging a cryostat.
a and a synchrotron radiation light outlet 3b opening from the space 3a to the outer circumferential side surface, forming a C-shape. The pair of superconducting coils 4 and 5 are saddle-shaped coils formed by winding superconducting conductors 4a and 5a each having a wedge-shaped cross section so as to have a fan-shaped planar shape, and are arranged along the particle orbit 2. The cross-sectional shape of the curved superconducting coil side is superconducting conductor 4a,
5a is a polymerized aggregate. Particle circulation path 6 in the center
A cryostat 7 having a C-shaped cross section for forming a synchrotron radiation light outlet 6a opening from the particle circulation passage 6 to the outer circumferential side face is connected to the synchrotron radiation light outlet 6.
a is arranged in the donut-shaped space 3a so as to face the synchrotron radiation light outlet 3b of the iron core 3, and is supported by the iron core 3 via a non-magnetic support 21.

The pair of superconducting coils 4 and 5 are mounted on a non-magnetic support 8 so as to face each other with the particle circulation path 6 and the synchrotron radiation light outlet 6a sandwiched between them from above and below.
is positioned and fixed in the cryostat 7 by a deflection magnetic field (dipolar magnetic field) B along the particle circulation path 6.
occurs.

[0013] Furthermore, the weight of the superconducting conductors 4a, 5a that constitute the coil sides of the pair of superconducting coils 4, 5 that are located on the side of the synchrotron radiation light outlet 6a and that face each other with the outlet 6a in between. Displacement correction coils 9 and 10 are arranged adjacent to the opposing sides of the combination and the opposite side. Each displacement correction coil 9, 10 is formed into a sheet shape by winding a conducting wire in a fan shape. The non-magnetic support 8 is arranged so that a compensation current flows in the opposite direction to the superconducting coils 4 and 5, and a compensation current flows in the same direction as the superconducting coils 4 and 5 to the side of the coil adjacent to the opposite side. It is fitted into and supported by the formed displacement correction coil fitting groove.

As detailed in FIG. 3, the compensation current control device for controlling the compensation current flowing through the displacement correction coils 9 and 10 connects the superconducting coil 4 (5) from the superconducting coil power supply 11.
), a superconducting coil current detector 12 that detects the value of the superconducting coil current im supplied to the superconducting coil current im, a function storage device 13 that stores a corresponding function of the optimum value of the compensation current is with respect to the value of the superconducting coil current im, and the superconducting coil Current detector 12
Based on the value of the superconducting coil current im detected by the superconducting coil current im, the optimum value of the compensation current value is is determined by referring to the corresponding function, and the displacement is corrected so as to supply the compensation current is to the displacement correction coil 9 (10). A compensation current command device 15 that controls the coil power supply 14 is provided. The function storage device 13 is provided with function changing means for storing or changing a corresponding function so as to enable optimal compensation current control in accordance with individual differences in generation of irregular magnetic fields of each superconducting deflection coil.

In the above configuration, the superconducting coils 4, 5
By passing a current through the magnetic field B, a deflecting magnetic field B is generated, which deflects the orbiting charged particles. And synchrotron radiation 1
6 is led out to the outside through the outlet ports 3b and 6a.

By the way, the superconducting coils 4 and 5 shown in FIG.
When a current im flows in the direction shown in a), 2 of the current flows between the opposing sides of the superconducting coils (superconducting conductors 4a and 5a).
An electromagnetic attractive force f proportional to the power of the force acts. This electromagnetic attraction force f acts on the inner coil sides and the outer coil sides, but the non-magnetic support 8 that supports both superconducting coils 4 and 5 secures the synchrotron radiation light outlet 6a. Since a C-shaped structure is formed within the cryostat 7 in order to elastically deforms to narrow it. This amount of elastic deformation is approximately equal to the superconducting coil current i
It is proportional to the square of m. Due to this deformation of the nonmagnetic support 8, the superconducting coils 4 and 5 are displaced as shown in FIG. 4(b). This displacement of the superconducting coil sides acts in the same manner as when a sheet-like current as shown in FIG. 4C is passed through the coil side arrangement region, and generates an irregular magnetic field.

In this embodiment, in order to correct this irregular magnetic field, a compensation current is flowing in the direction opposite to the sheet current through the displacement correction coils 9 and 10.

The displacement correction coils 9 and 10 are shown in FIG.
As shown in a) and (b), coil sides 9a and 10a through which compensation currents in the opposite direction to the superconducting coil current im flow are formed on opposite sides of the polymer of the superconducting conductor constituting the coil sides of the superconducting coils 4 and 5. A coil side 9 where a compensation current flows in the same direction as the superconducting coil current im on the opposite side of the polymer.
b and 10b, a current distribution state is created that approximately cancels out the sheet-like current, and generation of an irregular magnetic field is prevented.

Assuming that the non-magnetic support 8 supporting the superconducting coils 4 and 5 is elastically deformed, the amount of displacement δ on the side of the superconducting coil is proportional to the electromagnetic attractive force f, and the electromagnetic attractive force f is proportional to the superconducting coil current im. Since it is proportional to the square of δ∝f∝im
2 holds true. The magnetomotive force at which is generated in the irregular magnetic field based on the sheet-like current due to the displacement of the superconducting coil side is the product of the cross-sectional area (displacement area) of the sheet-like current and the current density j. Since the current density j of the sheet current is proportional to the superconducting coil current im, a
t∝δj∝im3 holds true. Therefore, in order to cause the displacement correction coils 9, 10 to generate a magnetomotive force that cancels the magnetomotive force at generated by the sheet-like current, the displacement correction coils 9, 10
It is necessary to supply a compensation current is approximately proportional to the third power of the superconducting coil current im.

In order to realize such compensation current supply control, the current detector 12 detects the value of the current im flowing through the superconducting coil 4 (5) and inputs it to the compensation current command device 15. The compensation current command device 15 refers to the function storage device 13 to determine the value of the compensation current is most suitable for canceling out the influence of the sheet-like current based on the displacement of the superconducting coil side due to the superconducting coil current im, and performs the compensation. The displacement correction coil power supply 14 is controlled to supply the current is to the displacement correction coil 9 (10).

[0021] If the value of the compensation current is is controlled in accordance with the value of the current im flowing through the superconducting coil 4 (5) in this way,
It is possible to stably accelerate or accumulate electrons ranging from low-energy electrons corresponding to a low deflection magnetic field to high-energy electrons corresponding to a high deflection magnetic field.

The uneven magnetic field correction technique using the displacement correction coils 9 and 10 described above can be applied to the inner coil side of the superconducting coil 4 (5) as well. Since the amount of displacement of the inner superconducting coil side is smaller than that of the outer superconducting coil side, the magnetomotive force (for example, the number of turns) of the displacement correction coil placed adjacent to the inner superconducting coil side is smaller than that of the outer superconducting coil side. The magnetomotive force of the displacement correction coil relative to the coil side may be smaller than, for example, the number of turns.

[0023] If displacement correction coils are provided on both the inner and outer periphery sides of the superconducting coil, more accurate correction of the irregular magnetic field can be realized.

In the above embodiment, the coil sides of the displacement correction coils 9 and 10 are arranged so as to correct the irregular magnetic field generated when the coil sides of the superconducting coils 4 and 5 are displaced in the direction of narrowing the synchrotron radiation light outlet 6a. Although the placement position has been determined, if the displacement direction of the coil sides of the superconducting coils 4 and 5 is perpendicular to this, the displacement correction coils 9 and 1
The arrangement position of the coil side 0 is also in the right angle direction, and when displacements in both directions occur in combination, the displacement correction coils 9 and 1
The placement position of 0 is also complex.

FIG. 6 is a longitudinal sectional side view showing another embodiment of the fan-shaped superconducting deflection magnet device constituting the electron storage ring for synchrotron radiation generation. This embodiment includes, in addition to the displacement correction coils 9 and 10, multipolar magnetic field correction coils 17 to 20 for compensating for irregular magnetic fields due to manufacturing errors. The multipolar magnetic field correction coils 17 to 20 are arranged on a concentric circle centered on the particle orbit 2 so as to be symmetrical with respect to a horizontal plane passing through the center. The rest of the structure is the same as the fan-shaped superconducting deflection magnet device described above.

By providing a correction coil for each cause of irregular magnetic field generation in this way, it becomes possible to correct the irregular magnetic field with high precision, and the uniformity of the deflection magnetic field can be greatly improved.

[0027]

As described above, the present invention is applicable to superconducting magnet devices in which an opening is provided on the outer circumferential side of a superconducting coil, such as a fan-shaped superconducting deflection magnet for an electron storage ring for synchrotron radiation generation. A uniform deflection magnetic field can be generated by correcting an irregular magnetic field generated by displacement of the sides of the superconducting coil by electromagnetic force caused by a current flowing through the coil.

[Brief explanation of the drawing]

FIG. 1 is a plan view of a fan-shaped superconducting deflection magnet device constituting an electron storage ring for synchrotron radiation generation according to an embodiment of the present invention.

FIG. 2 is a sectional view taken along line II-II in FIG. 1;

FIG. 3 is an electrical connection diagram of the magnet device.

FIG. 4 is an explanatory diagram showing the relationship between superconducting coil current, displacement of the superconducting coil side, and sheet current.

FIG. 5 is an explanatory diagram showing the relationship between the superconducting coil current, the displacement of the superconducting coil side, and the compensation current flowing through the displacement correction coil.

FIG. 6 is a longitudinal sectional side view of a fan-shaped superconducting deflection magnet device constituting an electron storage ring for synchrotron radiation generation according to another embodiment of the present invention.

[Explanation of symbols]

2 Particle orbit 3 Iron core 4, 5 Superconducting coil 6 Particle orbit passage 3b, 6a Synchrotron radiation light outlet 9, 10
Displacement correction coil 12 Current detector 13 Function storage device 14 Displacement correction coil power supply 15 Compensation current command device

Claims (9)

[Claims] 1. A superconducting magnet device in which a pair of superconducting coils wound in a fan shape are disposed facing each other at a predetermined interval on both sides of a particle circulation passage, and an opening is provided on the outer circumferential side of the particle circulation passage. A superconductor comprising: a displacement correction coil wound adjacent to both sides of the coil side located on the opening side of the coil; and a compensation current control device for controlling a compensation current flowing through the displacement correction coil. Magnetic device. 2. In claim 1, the displacement correction coil is provided not only on the curved outer circumference side of the superconducting coil side but also on the curved inner circumference side, and the number of turns of the coil located on the curved outer circumference side is changed to the curved inner circumference side. A superconducting magnet device characterized in that the number of turns is greater than the number of turns in the coil. 3. The superconducting magnet device according to claim 1, wherein the compensation current control device controls the value of the compensation current flowing through the displacement correction coil in accordance with the value of the current flowing through the superconducting coil. 4. In claim 1, the compensation current control device comprises a power source, a superconducting coil current detector, a function storage means for storing a correspondence function between a superconducting coil current value and an optimum compensation current value, and the correspondence function. and a function changing means for changing the superconducting coil current value detected by the superconducting coil current detector by referring to the corresponding function to obtain a compensation current value and supplying the compensation current to the displacement correction coil. and a control means for controlling the power source. 5. A fan-shaped iron core having a C-shaped cross section and having a synchrotron radiation outlet opening from an internal donut-shaped space to an outer circumferential side surface, a cryostat disposed in the donut-shaped space, and a fan-shaped core wound in a fan shape. A superconducting magnet device comprising a pair of superconducting coils disposed in the cryostat so as to face each other with a particle circulation path in between, the coil being located on the side of the synchrotron radiation light outlet of the superconducting coils. A superconducting magnet device comprising: a displacement correction coil wound adjacent to both sides of the side; and a compensation current control device for controlling a compensation current flowing through the displacement correction coil. 6. The superconducting magnet device according to claim 1, further comprising a multipolar magnetic field correction coil for compensating for irregular magnetic fields due to manufacturing errors of the superconducting coil. 7. The superconducting magnet device according to claim 6, wherein the multipolar magnetic field correction coil is formed by a plurality of sheet-shaped coils. 8. According to claim 1 or 5, a displacement correction coil fitting groove is provided in the non-magnetic support that supports the superconducting coil, and the displacement correction coil is fitted into the fitting groove. A superconducting magnet device. 9. A particle accelerator comprising the superconducting magnet device according to claim 1 or 5.