JP2945158B2 - Deflection magnet for charged particle devices - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a superconducting deflection magnet for charged particles used for bending a traveling direction of charged particles in a synchrotron radiation light generator or the like.

[0002]

2. Description of the Related Art FIG. 7 shows "Nakata et al.," Three-Dimensional Magnetic Field Analysis of Superconducting 180 ° Deflection Magnet by Vector Potential Method ", Conference on Computation of Electron Magnetic Field, Computer Mag (September 1989) 321. Pp. 324,
(J. NAKATA et al., "THREE-DIMENSI
ONAL MAGNETIC FIELD ANALY
SYS OF SUPERCONDUCTING 18
0 @ BENDING MAGNETS BY POTE
NTIAL FEM USING SUPERCOMP
UTERS ”, CONFERENCE ON COMP
UTATION OF ELECTROMAMAGNET
IC FIELDS, COMPUMAG SEPTEM
(BER 3-7, 1989, TOKYO, JAPAN)
FIG. 2 is an exploded perspective view showing the conventional superconducting deflection magnet shown in FIG. In the figure, coil 1
Consists of an outer-diameter coil winding 2, an inner-diameter coil winding 3, and a flip-up end coil winding 4 connecting these. Reference numeral 5 denotes a cryostat, 6 denotes charged particles, 11 denotes a return yoke made of a ferromagnetic material such as iron, and 51 denotes a window through which a beam duct is passed.

Next, the operation will be described. The charged particles 6 receive a force in the radial direction mainly by a vertical magnetic field generated by the coil 1 (a magnetic field interlinking a pair of opposing coils 1) and are deflected by 180 °. At this time, the charged particles 6 generate emitted light in a direction perpendicular to the radial direction (tangential direction of the beam orbit). In order to bend a high-energy beam with a small radius according to a design orbit, a highly uniform high magnetic field is required. A highly uniform magnetic field can be obtained by connecting the ends of the coil 1 with the flip-up end coil windings 4.

[0004] The cryostat 5 is a low-temperature container for keeping each coil 1 at a very low temperature. Cryostat 5
Is usually made of a non-magnetic metal such as stainless steel in order to prevent low-temperature brittleness and to prevent the magnetic field generated from the coil 1 from being distorted. In addition, when a high magnetic field is generated, a large leakage magnetic field is generated in the vicinity, which affects peripheral devices.
The return yoke 11 using a ferromagnetic material allows the coil 1
Shield.

The return yoke 11 has an inner diameter side return yoke 11 a and an outer diameter side return yoke 11 provided with a window 51 for passing a high vacuum beam duct through which the charged particles 6 pass.
b, upper and lower top plates 11c. When a high magnetic field is generated, each coil winding 2, 3, 4 and each return yoke 11
A strong electromagnetic force is generated in a complicated direction between a, 11b, and 11c.

[0006]

Since the conventional deflection magnet for a charged particle device is constructed as described above, it is impossible to adjust the distance between the coil winding and the return yoke. Electromagnetic force acting between the upper and lower ceilings, the electromagnetic force generated between the inner and outer coil windings and the inner return yoke, and a part of the outer and end coil windings It is difficult to balance the electromagnetic force generated between the return yoke and the outer diameter side return yoke, a strong electromagnetic force acts between the return yoke and the coil, and errors between the upper and lower coil windings and coil windings due to errors during coil assembly. There is a problem that an unbalanced magnetic attractive force is generated between the motor and the return yoke. Therefore, there is a problem that a supporting material for supporting a strong electromagnetic force is required, the structure of the deflection magnet becomes complicated, the total weight becomes heavy, and the consumption of the cryogen such as liquid helium increases.

Further, when a high magnetic field exceeding 2T is generated, the return yoke made of a ferromagnetic material causes magnetic saturation and lowers the magnetic permeability. The leakage magnetic field increases, adversely affecting the charged particles. Therefore, the amount of ferromagnetic material for shielding the leakage magnetic field is increased, the total weight of the deflection magnet is increased, and it is difficult to disassemble and transport the magnet.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide an electromagnetic force acting between an end coil winding and an upper and lower ceiling, and an inner coil and between an end coil and an inner return return yoke. And the electromagnetic force generated between the part end coil winding, the outer diameter side coil winding and the side return yoke can be balanced, and the radial electromagnetic force applied to the entire coil can be balanced. It is an object of the present invention to provide a deflection magnet for a charged particle device that does not substantially work and can adjust an installation error between a coil winding and a return yoke due to an error in assembling a coil or a manufacturing error.

It is another object of the present invention to provide a deflection magnet for a charged particle device capable of preventing a reduction in a leakage magnetic field shielding effect due to magnetic saturation of a ferromagnetic material and reducing a leakage magnetic field to the outside of the deflection magnet.

[0010]

A deflection magnet for a charged particle device according to the present invention has a plurality of movable ferromagnetic shims provided on a return yoke installed at a certain distance from a coil winding. is there.

In addition, a gap is provided in a return yoke installed at a certain distance from the coil winding, and the return yoke inside the deflection magnet is configured to be thicker than the outside return yoke across the gap. Things.

[0012]

According to the present invention, by providing a shim to adjust the distance between the coil winding and the return yoke, the electromagnetic force acting between the end coil winding and the upper and lower return yokes and the inner diameter side coil winding can be adjusted. The electromagnetic force generated between the wire and the end coil winding and the inner diameter return yoke and the electromagnetic force generated between the part end coil winding and the outer diameter coil and the outer diameter return yoke are substantially balanced. The electromagnetic force in the radial direction does not work between the entire coil and the return yoke, and the number of support members that support the electromagnetic force can be reduced. Further, by providing the movable ferromagnetic shim, it is possible to simplify correction of a coil assembly error and the like.

Further, by providing a gap between the return yokes, it is possible to prevent the leakage magnetic field from increasing due to the magnetic saturation of the ferromagnetic material, and to reduce the leakage magnetic field without increasing the weight of the ferromagnetic material.

[0014]

【Example】

Embodiment 1 FIGS. 1 and 2 show an embodiment of the present invention, where ρ is the radius of curvature of charged particles, o is the center of curvature, 7 is a movable ferromagnetic shim, and 8 moves the shim 7. Is a set screw. 9 is an air gap. In addition, the same reference numerals as those in FIG. 7 denote the same or corresponding parts.

The operation will be described below. When the coil 1 is energized, a magnetic field is generated in the magnet. With this magnetic field,
The charged particle receives Lorentz force. Utilizing this Lorentz force, charged particles 6 incident from the incident beam line
Bend. At that time, radiation light is generated in the tangential direction of the beam orbit. When a magnetic field is generated, an electromagnetic force is generated in which the coil windings 2, 3, and 4 are drawn to the return yoke 11. Since the return yoke 11 is installed so as to surround the winding of the coil 1, an electromagnetic force in a complicated direction is generated. By combining these forces, a strong radial electromagnetic force acts between the entire coil 1 and the return yoke 11. In this embodiment, a ferromagnetic shim 7 that is movable to the outside of the deflection magnet is provided on the upper and lower return yoke top plates 11c.
By installing such a return yoke 11,
The distance between the coil winding 1 and the upper and lower top plates 11c can be equivalently increased, and the electromagnetic force acting between the coil 1 and the return yoke 11 changes. Therefore, these electromagnetic forces can be balanced to make the radial electromagnetic force acting on the entire coil substantially zero.

Further, the coil 1 due to an assembly error of the coil 1
And the return yoke 11 can be finely adjusted , and the unbalanced magnetic attraction based on this error can be corrected. As a result, the radial electromagnetic force only corresponds to a small eccentricity such as a positional deviation when the magnet is excited, so that the supporting material to be supported can be extremely small. For this reason, the consumption of the cryogen such as liquid helium is drastically reduced, and the operating cost of the magnet becomes extremely low.

Further, when a high magnetic field is generated, the return yoke 11 made of a ferromagnetic material causes magnetic saturation. Therefore, the effect of shielding the leakage magnetic field is reduced, the leakage magnetic field to the outside of the deflection magnet is increased, and it is necessary to increase the amount of the ferromagnetic material for effective shielding, and the weight increases. However, in this embodiment, since the gap 9 is provided in the return yoke, the gap 9 temporarily increases the magnetic resistance. Therefore, the magnetic field penetrating into the outer return yoke W ₂ across the gap 9 is reduced, the magnetic saturation of the return yoke W ₂ is reduced, and the leakage magnetic field can be effectively shielded without increasing the amount of the return yoke 11. In particular, it is possible to reduce the magnetic field that invades the outside of the return yoke W ₂ by increasing the inside of the return yoke W ₁ across the air gap 9 more effectively.

Embodiments 2 to 4 FIGS. 3, 4 and 5 show other embodiments, respectively, in which ferromagnetic shims 7 having different moving directions are attached. FIG. 3 shows a movable ferromagnetic shim 7 operating inside the deflection magnet. FIG. 4 shows a movable ferromagnetic shim 7 shown in FIGS.
FIG. 5 shows a movable ferromagnetic shim operable in both directions inside and outside the magnet.

Although the shims 7 are attached to the upper and lower return yoke top plates 11c in FIGS. 3, 4 and 5, they may be installed on the outer return yoke 11b and the inner return yoke 11a. It can be adjusted in all directions by installing and using them in combination. Of course, it goes without saying that the same effects as those of the above embodiment can be obtained.

Embodiment 5 FIG. 6 shows another embodiment of the second invention, in which a gap 9 is provided in the upper and lower return yoke top plates 11c. Also,
The air gap 9 can be provided in the inner return yoke 11a, and can be provided in a plurality of places depending on the position and degree of magnetic saturation of the return yoke 11. Needless to say, the same effects as in the above embodiment can be obtained.

The first and second inventions of the present invention have their own effects. Therefore, even if they are used independently, the effects are not changed. Of course, the two effects can be simultaneously obtained by combining both. Can be.

Further, the coil 1 can use either superconducting or normal conducting. In the above embodiment, the deflection angle is 180 °, but the invention can be applied to other angles.

[0023]

As described above, according to the present invention, the distance between each coil winding and each return yoke can be adjusted by attaching a plurality of movable ferromagnetic shims to the return yoke. This makes it easy to balance the electromagnetic force acting between each coil winding and each return yoke, and the radial electromagnetic force acting between the coil and the return yoke can be made substantially zero. Further, the assembly error of the coil winding can be easily adjusted from the outside. Therefore, the number of support members can be reduced, the configuration of the apparatus can be easily made, the apparatus can be made high-performance, and the operation cost can be reduced.

Also, by providing a gap in the return yoke, it is possible to reduce the leakage magnetic field to the outside of the magnet without increasing the weight of the return yoke, to prevent the weight of the magnet from being increased, to move the deflection magnet, and to operate peripheral devices. There is an effect that the shield can be simplified.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of one embodiment of the present invention.

FIG. 2 is a plan sectional view of that of FIG.

FIG. 3 is a cross-sectional view of another embodiment of the present invention.

FIG. 4 is a cross-sectional view of yet another embodiment of the present invention.

FIG. 5 is a cross-sectional view of another embodiment of the present invention.

FIG. 6 is a cross-sectional view of another embodiment of the second or third aspect of the present invention.

FIG. 7 is an exploded perspective view, partly in section, of a conventional deflection magnet for a charged particle device.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 coil 2 outer diameter coil winding 3 inner diameter coil winding 4 end coil winding 6 charged particle 7 ferromagnetic shim 9 air gap 11 return yoke

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) H05H 7/00-7/22 G21K 1/08-1/093

Claims (3)

(57) [Claims] An outer diameter side coil winding, an inner diameter side coil winding,
And a return magnet surrounding the coil at a fixed distance, and a plurality of movable magnets. A deflection magnet for a charged particle device, comprising the return yoke provided with a ferromagnetic shim. 2. An outer diameter side coil winding, an inner diameter side coil winding,
And a return magnet surrounding the coil at a certain distance, and a return yoke surrounding the coil at a fixed distance. A deflection magnet for a charged particle device, comprising: the return yoke having a gap formed therein for reducing a magnetic field. 3. A charged particle apparatus for polarizing magnet of claim 2, wherein the across the gap from the magnet outside of the return yoke and thicker return yoke in the magnet.