Electromagnet for accelerator, method for modifying electromagnet for accelerator, and method for manufacturing electromagnet for accelerator

Abstract

To achieve the suppression of leakage magnetic fields and alignment of the beam direction with a minimum magnetomotive force.SOLUTION: An insertion light source electromagnet 10 includes a yoke 3, first coils 1a and 1b, entry-side second coils 2a and 2b, and exit-side second coils 2c and 2d arranged between the yoke 3, an entry-side upper end magnetic body 6a, an entry-side lower end magnetic body 6b, an exit-side upper end magnetic body 6c, and an exit-side lower end magnetic body 6d, the material volumes of the entry-side upper end magnetic body 6a and the entry-side lower end magnetic body 6b are the same or decreasing in the direction of beam propagation, and the material volumes of the exit-side upper end magnetic body 6c and the exit-side lower end magnetic body 6d are the same or decrease in the direction opposite to the beam propagation direction.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an accelerator electromagnet, a method for modifying an accelerator electromagnet, and a method for manufacturing an accelerator electromagnet, and more particularly to an accelerator electromagnet, a method for modifying an accelerator electromagnet, and a method for manufacturing an accelerator electromagnet that are highly suitable for an insertion light source device in a synchrotron radiation facility. [Background technology]

[0002] As an example of a deflection magnet with a sub-pole and a device using a deflection magnet, Patent Document 1 describes a deflection magnet with a main pole that deflects a charged particle beam, in which a sub-pole that generates a magnetic field of opposite polarity to that of the main pole is provided at the front end face of the main pole, and this sub-pole changes the distribution of the leakage magnetic field of the main pole, thereby adjusting the focusing force of the beam. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2001-23798 Summary of the Invention [Problem to be solved by the invention]

[0004] An accelerator is a device that accelerates charged particles such as electrons, protons, and ions to high speeds, and is used in nuclear and particle physics experimental facilities, medical application facilities such as particle beam therapy, and synchrotron radiation facilities.

[0005] Of these, synchrotron radiation facilities accelerate charged particle beams (mainly electrons) to speeds close to the speed of light and utilize the synchrotron radiation generated when the electrons are bent as they move along an orbit formed by a combination of bending electromagnets.

[0006] The synchrotron radiation used includes white synchrotron radiation emitted from bending electromagnets and synchrotron radiation with the desired optical energy as electromagnetic waves emitted when electrons installed in the linear section of the accelerator are made to meander using an inserted light source.

[0007] To make the electrons meander, the insertion device must generate an internal magnetic field that is different from the magnetic field of the bending magnet. However, because the generated magnetic field affects the beam trajectory outside the insertion device, the magnetomotive force and shape of the insertion device magnet must be adjusted to minimize the magnetic field on the surrounding area. Adjustments to the magnetomotive force and shape of the magnet coil are also required for accelerator magnets other than the insertion device.

[0008] The following ideas have been proposed to minimize the influence of magnetic fields on accelerator magnets and insertion device magnets in applications other than their primary use:

[0009] Patent Document 1 proposes a structure in which a sub-magnetic pole of opposite polarity to the main magnetic pole is provided at the end of the magnet to minimize the effect of the magnetic field generated by the bending magnet on the beam outside the magnet.

[0010] As mentioned above, the influence of the magnetic field should be suppressed as much as possible in applications other than the main applications of accelerator magnets and, in particular, insertion magnets. Therefore, providing a magnetic body at the end of the insertion magnet is an effective method to suppress as much as possible the magnetic field acting on the beam outside the magnet (leakage magnetic field), as in Patent Document 1.

[0011] However, since the magnetic field generating region inside the electromagnet becomes narrower, the electrons may not be deflected to the desired degree, and the beam direction at the entrance and exit may shift, resulting in increased beam loss, so improvements are required.

[0012] The present invention provides an accelerator electromagnet that suppresses leakage magnetic fields and aligns beam directions with a minimum magnetomotive force, a method for modifying an accelerator electromagnet, and a method for manufacturing an accelerator electromagnet. [Means for solving the problem]

[0013] The present invention includes multiple means for solving the above-mentioned problems, and one example thereof includes a pair of upper and lower yokes, one or more coils arranged between the pair of upper and lower yokes, an entry-side upper end magnetic body arranged at an upper end of the yoke on the entry side in the direction of beam travel relative to the coils, an entry-side lower end magnetic body arranged at an end of the yoke on the entry side in the direction of beam travel below the coils, an exit-side upper end magnetic body arranged at an upper end of the yoke on the exit side in the direction of beam travel relative to the coils, and an exit-side lower end magnetic body arranged at an end of the yoke on the exit side in the direction of beam travel below the coils, wherein the material amounts of the entry-side upper end magnetic body and the entry-side lower end magnetic body are the same or smaller in the direction of beam travel, and the material amounts of the exit-side upper end magnetic body and the exit-side lower end magnetic body are the same or smaller in the direction opposite to the direction of beam travel. [Effects of the Invention]

[0014] According to the present invention, it is possible to suppress the leakage magnetic field and align the beam direction with a minimum magnetomotive force. Problems, configurations, and effects other than those described above will become clear from the following description of the embodiments. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a bird's-eye view of an insertion light source electromagnet according to a first embodiment. [Figure 2] 1 is a diagram showing a cross section of an insertion light source electromagnet according to a first embodiment. [Figure 3] FIG. 1 is a cross-sectional view of a conventional insertion source electromagnet. [Figure 4] FIG. 1 is a cross-sectional view of a conventional insertion source electromagnet. [Figure 5] 10 is a diagram showing a cross section of an insertion light source electromagnet according to a second embodiment. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0016] Hereinafter, an accelerator electromagnet, a method for modifying an accelerator electromagnet, and a method for manufacturing an accelerator electromagnet according to embodiments of the present invention will be described with reference to the drawings.

[0017] It should be noted that the following are merely examples of implementation and are not intended to limit the content of the invention to the specific embodiments described below. The invention itself can be implemented in various forms in accordance with the content described in the claims.

[0018] In the following embodiments, an example in which the present invention is applied to a three-pole insertion source electromagnet will be described, but the present invention can also be applied to electromagnets with five or more poles, for example. Also, the present invention can be applied to general accelerator electromagnets used to deflect charged particles.

[0019] Furthermore, in the drawings used in this specification, the same or corresponding components are denoted by the same or similar reference numerals, and repeated description of these components may be omitted.

[0020] <Embodiment 1> A first embodiment of the accelerator electromagnet, accelerator electromagnet remodeling method, and accelerator electromagnet manufacturing method of the present invention will be described with reference to FIGS. 1 to 4. FIG.

[0021] First, the overall configuration of the insertion source electromagnet will be described with reference to Fig. 1. Fig. 1 shows a bird's-eye view of the insertion source electromagnet in the first embodiment.

[0022] The insertion device electromagnet 10 shown in Figure 1 is a device that significantly deflects a charged particle beam (mainly electrons), generating high-energy synchrotron radiation as the electrons are deflected. The beam entering from the left side of Figure 1 traces an orbit that results in the maximum deflection near the center of the insertion device electromagnet 10, and exits the electromagnet from the right side of Figure 1.

[0023] The insertion light source electromagnet 10 includes a first coil 1, a second coil 2, a yoke 3, a first magnetic pole 4, a second magnetic pole 5, and a magnetic body 6.

[0024] FIG. 2 shows a cross-sectional view of the electromagnet for an insertion device according to the first embodiment.

[0025] As shown in FIG. 2, the first coil 1 is a coil that generates a strong magnetic field that significantly deflects the beam, and is composed of first coils 1a and 1b that are placed vertically opposite each other between a pair of upper and lower yokes 3 so as to generate a magnetic field that is directed from bottom to top at the center of the insertion device electromagnet 10.

[0026] The second coil 2 is a coil that generates a magnetic field of opposite polarity to the magnetic field generated by the first coil 1 in order to align the beam entrance and exit positions in the propagation direction of the beam in the insertion light source electromagnet 10. As shown in FIG. 2, the second coil 2 is composed of entrance-side second coils 2a and 2b that are placed vertically opposite each other between a pair of upper and lower yokes 3 on the left side of FIG. 2 so as to generate a magnetic field that flows from top to bottom, and exit-side second coils 2c and 2d that are placed vertically opposite each other between a pair of upper and lower yokes 3 on the right side of FIG. 2 so as to generate a magnetic field that flows from top to bottom.

[0027] The pair of upper and lower yokes 3 are members made of a magnetic material that strengthen the magnetic field generated by the first coil 1 and the second coil 2 and suppress the leakage magnetic field to the outside.

[0028] The first magnetic pole 4 is a magnetic pole for strengthening the magnetic field generated by the first coil 1, and is composed of a first magnetic pole 4a installed between the first coil 1a provided on the opposing surface of the yoke 3 on the vertically upper side, and a first magnetic pole 4b installed between the first coil 1b provided on the opposing surface of the yoke 3 on the vertically lower side, so as to strengthen the magnetic field in the central part in Figure 2.

[0029] The second magnetic pole 5 is a magnetic pole for strengthening the magnetic field generated by the second coil 2, and as shown in Figure 2, is composed of a second magnetic pole 5a installed between the entry side second coils 2a provided on the opposing surface of the yoke 3 on the vertically upper side, and a second magnetic pole 5b installed between the entry side second coils 2b provided on the opposing surface of the yoke 3 on the vertically lower side, so as to strengthen the magnetic field on the left side in Figure 2 (the entry side in the direction of beam propagation), and a second magnetic pole 5c installed between the exit side second coils 2c provided on the opposing surface of the yoke 3 on the vertically upper side, and a second magnetic pole 5d installed between the exit side second coils 2d provided on the opposing surface of the yoke 3 on the vertically lower side, so as to strengthen the magnetic field on the right side in Figure 2 (the exit side in the direction of beam propagation).

[0030] The magnetic body 6 is a component installed at the end of the yoke 3 to suppress leakage magnetic fields in the beam propagation direction and counter-propagation direction and to prevent excessive narrowing of the magnetic field region generated by the second coil 2. As shown in Fig. 2, the magnetic body 6 is composed of an entry-side upper-end magnetic body 6a installed at the end of the yoke 3 above the entry-side second coil 2a on the entry side of the yoke 3 in the beam propagation direction, an entry-side lower-end magnetic body 6b installed at the end of the yoke 3 below the entry-side second coil 2b on the entry side of the yoke 3 in the beam propagation direction, an exit-side upper-end magnetic body 6c installed at the end of the yoke 3 above the exit-side second coil 2c on the exit side of the yoke 3 in the beam propagation direction, and an exit-side lower-end magnetic body 6d installed at the end of the yoke 3 below the exit-side second coil 2d on the exit side of the yoke 3 in the beam propagation direction.

[0031] In the insertion device electromagnet 10, moving charged particles emit synchrotron radiation of the desired energy due to the magnetic field generated by the first coil 1 and the first magnetic pole 4, but if only this magnetic field is used, the beam direction at the entrance and exit of the insertion device electromagnet 10 will be significantly misaligned, making it impossible to form a circular orbit. Furthermore, if the magnetic field leaking from the insertion device electromagnet 10 in the beam direction is large, the beam direction will be misaligned, leading to beam loss.

[0032] The former problem is addressed by the insertion light source electromagnet 10 of this embodiment, which uses the magnetic field of opposite polarity generated by the second coil 2 and the second magnetic pole 5 to return the deviated beam direction to its original state.

[0033] To address the latter issue, the insertion light source electromagnet 10 of this embodiment has an entry-side upper end magnetic body 6 a, an entry-side lower end magnetic body 6 b, an exit-side upper end magnetic body 6 c, and an exit-side lower end magnetic body 6 d provided at the entry and exit ends of the yoke 3 in the direction of travel, in order to concentrate magnetic flux at the ends of the insertion light source electromagnet 10.

[0034] Here, to align the beam direction, it is necessary to make the sum of the integral of the magnetic field in the central magnetic field region in the beam direction (positive BL product) and the integral of the magnetic fields of opposite polarity in the magnetic field regions on both sides in the beam direction (negative BL product) zero; therefore, it is important to adjust the magnetomotive force and the shape of the electromagnet so that the sum becomes zero.

[0035] For this reason, in this embodiment, the material quantities of the inlet upper end magnetic body 6a and the inlet lower end magnetic body 6b are the same or smaller in the direction of beam travel, and the material quantities of the outlet upper end magnetic body 6c and the outlet lower end magnetic body 6d are the same or smaller in the direction opposite to the beam travel.

[0036] In this embodiment, the inlet upper end magnetic body 6a, the inlet lower end magnetic body 6b, the outlet upper end magnetic body 6c, and the outlet lower end magnetic body 6d have a stepped shape with their material amounts gradually decreasing.

[0037] That is, a pair of vertically arranged magnetic bodies, an upper entry-side end magnetic body 6a and a lower entry-side end magnetic body 6b, are provided at the most forward end of the yoke 3 in the beam traveling direction, and a pair of vertically arranged magnetic bodies, an upper exit-side end magnetic body 6c and a lower exit-side end magnetic body 6d, are provided at the most forward end of the yoke 3 in the beam traveling direction. Furthermore, the vertical spacing between the pair of magnetic bodies is narrowest at the most forward part in the beam traveling direction on the side of the upper exit-side end magnetic body 6c and the lower exit-side end magnetic body 6d, and remains constant or widens toward the rear in the beam traveling direction, while it is narrowest at the most rear part in the beam traveling direction on the side of the upper entry-side end magnetic body 6a and the lower entry-side end magnetic body 6b, and remains constant or widens toward the front.

[0038] The vertical spacing at the narrowest position between the inlet upper end magnetic body 6a and the inlet lower end magnetic body 6b, and the vertical spacing at the narrowest position between the outlet upper end magnetic body 6c and the outlet lower end magnetic body 6d can be the same as or wider than the first magnetic pole 4 and the second magnetic pole 5, which are the minimum spacings required to ensure beam passage space.

[0039] Furthermore, the inlet upper end magnetic body 6a, the inlet lower end magnetic body 6b, the outlet upper end magnetic body 6c, and the outlet lower end magnetic body 6d all have the same shape in the beam traveling direction.

[0040] Furthermore, the inlet upper end magnetic body 6a, the inlet lower end magnetic body 6b, the outlet upper end magnetic body 6c, and the outlet lower end magnetic body 6d all have the same shape in the direction perpendicular to the beam traveling direction.

[0041] It goes without saying that manufacturing errors are allowed for both the shape in the beam propagation direction and the shape in the direction perpendicular to the beam propagation direction.

[0042] Next, a method for modifying the insertion light source electromagnet 10 according to this embodiment, which includes a pair of upper and lower yokes 3, and one or more first coils 1a, 1b, entry-side second coils 2a, 2b, and exit-side second coils 2c, 2d provided between the pair of upper and lower yokes 3, will be described below.

[0043] First, the entry-side upper-end magnetic body 6a and the entry-side lower-end magnetic body 6b, whose material quantities are the same or smaller in the direction of beam propagation, are provided at the upper and lower ends of the yoke 3 on the entry side of the beam propagation direction from the coils of the existing insertion source electromagnet (here, the entry-side second coils 2a and 2b). In no particular order, the exit-side upper-end magnetic body 6c and the exit-side lower-end magnetic body 6d, whose material quantities are the same or smaller in the direction opposite to the beam propagation direction, are provided at the upper and lower ends of the yoke 3 on the exit side of the beam propagation direction from the coils of the insertion source electromagnet (here, the exit-side second coils 2c and 2d). This results in the insertion source electromagnet 10 according to this embodiment, as shown in FIG. 1 above.

[0044] Next, a method for manufacturing the insertion source electromagnet 10 according to this embodiment will be described below.

[0045] First, the pair of upper and lower yokes 3, and one or more first coils 1a, 1b, entry-side second coils 2a, 2b, and exit-side second coils 2c, 2d provided between the pair of upper and lower yokes 3 are fabricated and installed at predetermined positions. These first coils 1a, 1b, entry-side second coils 2a, 2b, and exit-side second coils 2c, 2d can be fabricated by known methods.

[0046] Next, in no particular order, entry-side upper-end magnetic bodies 6a and entry-side lower-end magnetic bodies 6b, whose material quantities are the same or decrease in accordance with the beam propagation direction, are fabricated from entry-side second coils 2a and 2b at the upper and lower ends of yoke 3 on the entry side of the beam propagation direction, and installed at the entry side end of yoke 3 in the beam propagation direction, and exit-side upper-end magnetic bodies 6c and exit-side lower-end magnetic bodies 6d, whose material quantities are the same or decrease in accordance with the direction opposite to the beam propagation direction, are fabricated from exit-side second coils 2c and 2d at the upper and lower ends of yoke 3 on the exit side of the beam propagation direction, and installed at the exit side end of yoke 3 in the beam propagation direction. This results in the insertion light source electromagnet 10 according to this embodiment as shown in FIG. 1 described above.

[0047] The effects of this embodiment will be described below by comparing Conventional Example 1 and Conventional Example 2.

[0048] FIG. 3 shows a cross-sectional view of the insertion source electromagnet 10A of Conventional Example 1. This is a configuration in which no magnetic body is provided at the end of the yoke 3A that constitutes the insertion source electromagnet 10A. In the insertion source electromagnet 10A shown in FIG. 3, no magnetic body is provided at the end of the yoke 3A, so the magnetic flux at the end spreads widely outside the insertion source electromagnet 10A. Note that this insertion source electromagnet 10A has the advantage that the integral range of the negative BL product generated by the second coil 2 and the second magnetic pole 5 is widened, thereby making it possible to reduce the magnetomotive force of the second coil 2, and therefore this configuration may be adopted depending on the application.

[0049] FIG. 4 shows a cross-sectional view of an insertion light source electromagnet 10B according to a second conventional example. This shows a configuration in which rectangular parallelepiped magnetic bodies are provided at the ends of the yoke 3B of the insertion light source electromagnet 10B. In the insertion light source electromagnet 10B shown in FIG. 4, the upper entry-side end magnetic body 7a, the lower entry-side end magnetic body 7b, the upper exit-side end magnetic body 7c, and the lower exit-side end magnetic body 7d are all rectangular parallelepiped. This has the advantage that the magnetic flux does not spread outside the insertion light source electromagnet 10B, thereby suppressing leakage of the magnetic field. However, the insertion light source electromagnet 10B has a problem in that the integration range of the negative BL product generated by the second coil 2 and the second magnetic pole 5 is narrowed, which requires a large magnetomotive force from the second coil 2.

[0050] In contrast, in the insertion source electromagnet 10 of this embodiment, the material volumes of the entry-side upper end magnetic body 6a and the entry-side lower end magnetic body 6b are the same or smaller in the beam propagation direction, and the material volumes of the exit-side upper end magnetic body 6c and the exit-side lower end magnetic body 6d are the same or smaller in the direction opposite to the beam propagation direction, thereby suppressing outward magnetic flux. Furthermore, the material volume of the magnetic body is gradually reduced from the end of the insertion source electromagnet 10 to the second coil 2, thereby enabling the magnetic field region generated by the second coil 2 and the second magnetic pole 5 to be wider than that of the insertion source electromagnet 10B of Prior Art 2 shown in Fig. 4 . Therefore, the magnetomotive force of the second coil 2 can be reduced to a value smaller than that of the insertion source electromagnet 10A of Prior Art 1 shown in Fig. 3 . Therefore, the desired amount of electron deflection can be achieved with a minimum magnetomotive force, and the beam direction at the entrance and exit of the insertion source electromagnet 10 can be more easily aligned than in the past.

[0051] Furthermore, the inlet upper end magnetic body 6a, the inlet lower end magnetic body 6b, the outlet upper end magnetic body 6c, and the outlet lower end magnetic body 6d have a stepped shape and the material volume decreases in stages, making the structure easy to manufacture.

[0052] Furthermore, the inlet upper end magnetic body 6a, the inlet lower end magnetic body 6b, the outlet upper end magnetic body 6c, and the outlet lower end magnetic body 6d all have the same shape in the direction of beam travel, and the inlet upper end magnetic body 6a, the inlet lower end magnetic body 6b, the outlet upper end magnetic body 6c, and the outlet lower end magnetic body 6d all have the same shape in the direction perpendicular to the direction of beam travel, which makes it very easy to adjust the magnetomotive force.

[0053] <Embodiment 2> An accelerator electromagnet, a method for modifying an accelerator electromagnet, and a method for manufacturing an accelerator electromagnet according to a second embodiment of the present invention will be described with reference to Fig. 5. Fig. 5 shows a cross-sectional view of an insertion source electromagnet according to the second embodiment.

[0054] In the insertion light source electromagnet 10C of this embodiment shown in FIG. 5, the entry-side upper-end magnetic body 8a provided at the upper end of the yoke 3C on the entry side in the beam traveling direction, the entry-side lower-end magnetic body 8b provided at the lower end of the entry side in the traveling direction, the exit-side upper-end magnetic body 8c provided at the upper end of the yoke 3C on the exit side in the beam traveling direction, and the exit-side lower-end magnetic body 8d provided at the lower end of the exit side in the traveling direction have smoothly inclined shapes and small amounts of material.

[0055] The other configurations and operations are substantially the same as those of the accelerator electromagnet, accelerator electromagnet modification method, and accelerator electromagnet manufacturing method of the first embodiment described above, and details thereof will be omitted.

[0056] The accelerator electromagnet, accelerator electromagnet modification method, and accelerator electromagnet manufacturing method of embodiment 2 of the present invention also provide substantially the same effects as the accelerator electromagnet, accelerator electromagnet modification method, and accelerator electromagnet manufacturing method of embodiment 1 described above.

[0057] Furthermore, the inlet upper end magnetic body 8a, the inlet lower end magnetic body 8b, the outlet upper end magnetic body 8c, and the outlet lower end magnetic body 8d have a smoothly inclined shape with a small amount of material, which makes them easy to process and therefore easy to manufacture.

[0058] <Embodiment 3> An accelerator electromagnet, a method for modifying an accelerator electromagnet, and a method for manufacturing an accelerator electromagnet according to a third embodiment of the present invention will be described.

[0059] In this embodiment, the inlet upper end magnetic body 6a, the inlet lower end magnetic body 6b, the outlet upper end magnetic body 6c, and the outlet lower end magnetic body 6d of embodiment 1 are manufactured by combining rectangular block parts.

[0060] The other configurations and operations are substantially the same as those of the accelerator electromagnet, accelerator electromagnet modification method, and accelerator electromagnet manufacturing method of the first embodiment described above, and details thereof will be omitted.

[0061] The accelerator electromagnet, accelerator electromagnet modification method, and accelerator electromagnet manufacturing method of embodiment 3 of the present invention also provide substantially the same effects as the accelerator electromagnet, accelerator electromagnet modification method, and accelerator electromagnet manufacturing method of embodiment 1 described above.

[0062] Furthermore, the inlet-side upper end magnetic body 6a, the inlet-side lower end magnetic body 6b, the outlet-side upper end magnetic body 6c, and the outlet-side lower end magnetic body 6d are configured by combining rectangular parallelepiped block components. This allows the amount of material to be increased or decreased depending on the magnetic field environment within the facility when the insertion device is installed in a synchrotron radiation facility, and magnetic field adjustment is easier than in the other embodiments, making it easier to suppress magnetic field leakage and align the beam direction.

[0063] <Other> It should be noted that the present invention is not limited to the above-described embodiment, and includes various modifications. The above-described embodiment has been described in detail to clearly explain the present invention, and the present invention is not necessarily limited to an embodiment having all of the described configurations.

[0064] It is also possible to replace part of the configuration of one embodiment with the configuration of another embodiment, or to add the configuration of another embodiment to the configuration of one embodiment, or to add, delete, or replace part of the configuration of each embodiment with the configuration of another embodiment.

[0065] For example, in any of the above-mentioned embodiments 1 to 3, the inlet upper end magnetic bodies 6a, 8a, the inlet lower end magnetic bodies 6b, 8b, the outlet upper end magnetic bodies 6c, 8c, and the outlet lower end magnetic bodies 6d, 8d all have the same shape in the direction of beam travel, but the shape in the direction of beam travel does not have to be the same as long as the amount of material in each magnetic body is the same or smaller in the direction of beam travel or the amount of material is the same or smaller in the opposite direction to the direction of beam travel, and may be different shapes.

[0066] For example, at the inlet upper end and outlet lower end, inlet upper end magnetic body 6a and outlet lower end magnetic body 6d can be used, which have a stepped shape with the material amount gradually decreasing, as in embodiment 1, and at the inlet lower end and outlet upper end, inlet lower end magnetic body 8b and outlet upper end magnetic body 8c can be used, which have a smoothly sloping shape with the material amount decreasing, as in embodiment 2. In this case, it is strongly desirable to pay attention to the top and bottom shapes so that the sum of the integral value of the magnetic field in the central magnetic field region in the beam direction and the integral value of the magnetic fields of opposite polarity in the magnetic field regions on both sides in the beam direction becomes zero.

[0067] Furthermore, in all of the above-described first to third embodiments, the inlet-side upper end magnetic bodies 6a, 8a, the inlet-side lower end magnetic bodies 6b, 8b, the outlet-side upper end magnetic bodies 6c, 8c, and the outlet-side lower end magnetic bodies 6d, 8d all have the same shape perpendicular to the beam propagation direction, but the shapes of the beam passage area and areas other than the vicinity thereof may be different. If different shapes are used, it is strongly desirable to pay attention to the shape in the vertical direction so that the sum of the integral of the magnetic field in the central magnetic field area in the beam direction and the integral of the magnetic fields of opposite polarity in the magnetic field areas on both sides in the beam direction becomes zero, as described above. [Explanation of symbols]

[0068] 1,1a,1b…First Korra 2…Second Korra 2a, 2b…the second corner on the entrance side 2c, 2d…The second corner from the exit side 3,3A,3B,3C…Yok 4, 4a, 4b… First magnetic pole 5, 5a, 5b, 5c, 5d… Second magnetic pole 6…Magnetic bodies 6a, 8a… Magnetic body at the upper end of the side 6b, 8b… Magnetic body at the lower end of the side 6c, 8c… magnetic body at the upper end of the side 6d, 8d… magnetic body at the lower side end 7a, 7b, 7c, 7d… End magnetic bodies 10, 10C… Insert the light source electromagnet (electromagnet for accelerator) 10A, 10B… Insert the light source electromagnet (for example)

Claims

1. A pair of upper and lower yokes, one or more coils provided between the pair of upper and lower yokes; an inlet upper end magnetic body provided at an upper end of the yoke on the inlet side in the beam traveling direction from the coil; an inlet lower end magnetic body provided at an end portion below the inlet side of the yoke in the beam traveling direction from the coil; an exit-side upper end magnetic body provided at an end portion above the coil on the exit side of the yoke in the beam traveling direction; an exit-side lower end magnetic body provided at an end portion of the yoke below the coil on the exit side in the beam traveling direction, the inlet-side upper end magnetic body and the inlet-side lower end magnetic body have the same or smaller material volume along the traveling direction of the beam, The magnetic body at the upper end of the exit side and the magnetic body at the lower end of the exit side have the same or smaller material amounts in the direction opposite to the traveling direction of the beam. Electromagnet for accelerator.

2. 2. The accelerator electromagnet according to claim 1, The inlet-side upper end magnetic body, the inlet-side lower end magnetic body, the outlet-side upper end magnetic body, and the outlet-side lower end magnetic body are formed in a stepped shape, with the amount of material decreasing stepwise. Electromagnet for accelerator.

3. 2. The accelerator electromagnet according to claim 1, The inlet-side upper end magnetic body, the inlet-side lower end magnetic body, the outlet-side upper end magnetic body, and the outlet-side lower end magnetic body have a smoothly inclined shape and the material amount is small. Electromagnet for accelerator.

4. 3. The accelerator electromagnet according to claim 2, The inlet-side upper end magnetic body, the inlet-side lower end magnetic body, the outlet-side upper end magnetic body, and the outlet-side lower end magnetic body are configured by a combination of rectangular parallelepiped block parts. Electromagnet for accelerator.

5. 2. The accelerator electromagnet according to claim 1, The inlet-side upper end magnetic body, the inlet-side lower end magnetic body, the outlet-side upper end magnetic body, and the outlet-side lower end magnetic body all have the same shape in the traveling direction of the beam. Electromagnet for accelerator.

6. 2. The accelerator electromagnet according to claim 1, The inlet-side upper end magnetic body, the inlet-side lower end magnetic body, the outlet-side upper end magnetic body, and the outlet-side lower end magnetic body all have the same shape in a direction perpendicular to the traveling direction of the beam. Electromagnet for accelerator.

7. 2. The accelerator electromagnet according to claim 1, The accelerator magnet is an insertion light source magnet. Electromagnet for accelerator.

8. A method for modifying an accelerator electromagnet including a pair of upper and lower yokes and one or more coils provided between the pair of upper and lower yokes, comprising: providing an entry-side upper end magnetic body and an entry-side lower end magnetic body, the material amounts of which are equal to or smaller than the material amounts of which are ... and providing an exit-side upper end magnetic body and an exit-side lower end magnetic body at the upper end and lower end of the exit side of the yoke in the beam traveling direction from the coil, the material amounts of which are the same or smaller in the direction opposite to the beam traveling direction. How to modify an accelerator electromagnet.

9. A method for manufacturing an electromagnet for an accelerator, comprising: providing a pair of upper and lower yokes and one or more coils provided between the pair of upper and lower yokes; providing an entry-side upper end magnetic body and an entry-side lower end magnetic body, the material amounts of which are equal to or smaller than the material amounts of the entry-side upper end magnetic body and the entry-side lower end magnetic body, at upper and lower ends of the entry side of the yoke in the beam traveling direction relative to the coil; and providing an exit-side upper end magnetic body and an exit-side lower end magnetic body at the upper and lower ends of the exit side of the yoke in the beam traveling direction from the coil, the material amounts of which are the same or smaller in the direction opposite to the beam traveling direction. Manufacturing method for accelerator electromagnets.

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