JP2511990B2 - Deflection magnet and its excitation device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a deflection magnet and its exciting device,
In particular, the present invention relates to an electron synchrotron intended to generate synchrotron radiation, or a deflection magnet suitable for an electron storage ring, and an exciting device therefor.

[Conventional technology]

Conventionally, as a method of correcting a deflection magnetic field in a superconducting deflection magnet which is a combination of an iron core with magnetic poles and an exciting coil (superconducting coil), the exciting coil (superconducting coil) is divided into multiple layers and excited independently. A method of providing unevenness on the surface is known. Note that as a literature on this type of magnetic field correction method, for example, F. R. Hason et al., Minutes of the 12th International Conference on the design of ultraferrite magnets for multiple teraelectron bolt storage rings and high energy acceleration (FRHUSON, et al. , DESIGN OF S
UPERFERRIC MAGNETS FOR A MULTI-TeV STORAGE RING, PR
OCEEDINGS OF THE 12TH INTERNATIONAL CONFERENCE ON
HIGH-ENERGY ACCELERATORS).

[Problems to be solved by the invention]

The conventional magnetic field correction method described above is intended for a deflection magnet for a giant accelerator. The deflection angle of particles in the deflection magnet is as small as several m rad, and the shape of the deflection magnet is almost linear. However, when the same correction method is applied to a superconducting deflection magnet for a small electron storage ring for the purpose of generating synchrotron radiation (hereinafter referred to as radiation), the deflection magnet changes from linear to fan-shaped. And the superconducting coil must be separated in the direction perpendicular to the orbital plane of the charged particle beam in order to avoid spatial interference between the beam line for radiating the synchrotron radiation of the charged particle beam and the exciting coil (superconducting coil). There is a problem that the winding arrangement range is greatly limited, and it is difficult to correct the deflection magnetic field by the above-mentioned conventional method.

The present invention has been made in view of the above points, and an object of the present invention is to provide a deflection magnet suitable for a small electron storage ring that can easily correct the deflection magnetic field, and an excitation device for the deflection magnet. is there.

[Means for solving problems]

The above-mentioned problems are caused by the facing magnetic pole faces of the iron core.
A deflection magnet in which a magnetic field correction coil is arranged so as to sandwich a vacuum chamber for accumulating a charged particle beam between opposing magnetic poles provided in an iron core, and an internal magnetic pole facing each other are provided, and charged particles are provided between the opposing magnetic poles. An iron core having a substantially fan-shaped or semi-circular horizontal cross section that forms a gear cup in which a vacuum chamber for accumulating a beam is installed.
A pair of upper and lower exciting coils for generating a deflection magnetic field in the gear between the magnetic poles of the iron core, a power source for the exciting coil for supplying a current to the exciting coil, and the vacuum chains are respectively sandwiched between the facing magnetic pole faces of the iron core. A magnetic field correction coil installed, a magnetic field correction coil power supply for supplying a current to the magnetic field correction coil, a current detector for detecting the current of the exciting coil, a current value detected by the current detector, and this current A storage device that stores an excitation pattern of the magnetic field correction coil with respect to a value, a current value of the magnetic field correction coil is determined based on the detected current value of the excitation coil and storage data of the storage device, and the magnetic field correction coil power supply is configured to This is solved by using a deflection magnet excitation device provided with a current command device that commands a current value supplied to the magnetic field correction coil.

[Action]

In the present invention, since the deflection magnetic field by the deflection magnet is made to have a homogeneity of a predetermined value or less, a magnetic field correction coil provided in parallel to each of the facing magnetic pole faces generates a magnetic field for canceling the non-uniform magnetic field of the deflection magnetic field. By maintaining the deflection magnetic field to have a homogeneity of a predetermined value or less, the intended purpose is achieved.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS.

First Embodiment FIG. 1 is a sectional view of a deflecting magnet, which is taken along line A- of FIG.
A section is shown. The cross section of the magnetic field correction coil 1 is elongated horizontally,
A vacuum chamber 3 is arranged between the magnetic poles 10a and 10b provided inside the iron core 8 with a gear gap. The cross-sectional shapes of the upper magnetic field correction coil 1a and the lower magnetic field correction coil 1b are symmetrical with respect to the orbital plane of the charged particle beam 6. Magnetic pole
A cryostat 4 having a built-in exciting coil (superconducting coil) 9 is arranged on both sides of 10a and 10b, and a beamline 5
It is separated into upper and lower parts to secure space. The cross sections of the iron core 8 and the exciting coils (superconducting coils) 9a and 9b are symmetrical with the orbital plane of the charged particle beam 6 as in the magnetic field correction coil 1. The iron core 8 has a structure surrounding the upper and lower superconducting coils 9a and 9b, and forms a magnetic circuit so as to generate a deflection magnetic field in the gears of the magnetic poles 10a and 10b. A tunnel 11 is provided in each of the outer return yokes of the iron core 8, and a beam line 5 connected to the vacuum chamber 3 extends to the outside of the iron core 8. The emitted light 7 is emitted through the beam line 5.

FIG. 2 is a plan view of the deflection magnet of the small electron storage ring. The magnetic field correction coil 1 is arranged parallel to the trajectory of the charged particle beam 6 passing through the vacuum chamber 3, and the connecting boxes 2 of the wire are attached to both ends of the magnetic field correction coil 1 protruding from the end of the iron core 8. There is. There are two magnetic field correction coils 1 above and below the vacuum chamber 3. On both sides of the magnetic field correction coil 1, there are arranged semicircular cryostats 4 incorporating an exciting coil (superconducting coil). There are two cryostats 4 above and below a beam line 5 for guiding the radiation 7 emitted in the tangential direction of the charged particle beam 6 to the outside of the iron core 8.

FIG. 3 is a sectional view of the magnetic field correction coil 1. The magnetic field correction coil 1 is arranged in close contact with the magnetic pole surface of the magnetic pole 10. The wire 12 of the magnetic field correction coil 1 is wound around a winding frame 14 and spacers 13 for adjusting the arrangement of the wire 12 are provided in places. The wound wire 12 is sandwiched by a winding frame 14 from above and below and formed into a flat plate shape. The arrangement of the strands 12, which will be described in detail later, is determined by optimization by a computer, and the size of the uniform magnetic field space 15, the shape of the magnetic field distribution to be corrected, and the size of the space where the magnetic field correction coil 1 can be arranged. Etc. The arrangement of the wires 12 shown in FIG. 3 is four poles or six.
It is a diagram schematically showing the wire arrangement optimized by using a computer for the purpose of correcting the polar magnetic field.

In the magnetic field correction coil 1 having a 4-pole or 6-pole magnetic field, the third
As shown in the figure, there is a property that there is an empty space in which the strands 12 are not arranged between the strand groups on both sides and the central strand group. This property can be inferred from the conceptual diagram of the current distribution in the magnetic field correction coils for the 4-pole and 6-pole magnetic fields shown in FIGS.

Although the magnetic field correction coil 1 has a flat plate shape in the first embodiment, it may have a more complicated shape. In short, any shape can be used as long as the magnetic field correction coil 1 can be arranged in an empty space.

FIG. 4 shows a magnetic field correction coil 1 utilizing the above-mentioned properties.
It shows the fixing method of. The magnetic field correction coil 1 is
The magnetic pole 10 and the screw 16 are fixed at the spacer 13 portion shown in FIG. The magnetic field correction coil 1 and the vacuum chamber 3
It may be fixed to.

Next, the operation of the first embodiment will be described. Prior to this, the principle of the present invention, that is, the method of arranging the wires 12 of the magnetic field correction coil 1 for generating a desired magnetic field will be described.

Let x and y be the displacement coordinates from the central orbit of the charged particle beam 6 in the horizontal and vertical directions in the plane orthogonal to the electron orbit plane, and let B _x (x, y) and B _y (x, y) be points ( x, y) and the magnetic flux densities in the x and y directions, and B _yo is the target value of the deflection magnetic field. No. 17 in deflection magnet for particle accelerator
As shown in the figure, in a region within a diagonal line having a width w along the charged particle beam and a height h orthogonal to this (hereinafter referred to as a uniform magnetic field space), the magnetic field uniformity defined by the following equation (1) is It needs to be around 10 ^{-4 at} a time. Here, w and h are constants obtained from the magnet arrangement of the storage ring.

In this case, when B _y on the orbital plane is expanded at the charged particle beam position (y = 0), B _y (x, y = 0) = B _yo (1 + ax + bx ² + cx ³ + ...) (2) The second and subsequent terms are the components of the multipole magnetic field that make the deflection magnetic field inhomogeneous, and are the 4-pole, 6-pole, and 8-pole magnetic fields in order from the second term. The complex representation the magnetic flux density B (x, y) = B y (x, y) + iB x (x, y) ... (3) with respect to which the xy plane origin, i.e. deployed at the location of the charged particle beam Then, the multipole magnetic field components of B _x and B _y can be displayed together.

_{B = B y + iB x =} B yo (1 + aZ + bZ 2 + cZ 3 + ...) ... (4) where the Z = x + iy, a i ² = -1.

In order to correct the deflection magnetic field and obtain a uniform magnetic field in the uniform magnetic field space based on the above-mentioned properties related to the magnetic field, it is only necessary to generate the magnetic field B ′ of the following equation by the magnetic field correction coil and cancel the error magnetic field. I understand. However, in normal cases, the higher-order terms can be ignored, so it is sufficient to keep the first three terms.

B - The _{'= B yo (aZ + bZ} 2 + cZ 3 + ...) ... (4'), since (4 ') the principle of superposition of multipole magnetic field is established with respect to the correction of the magnetic field from the equation, separately for each multi-pole magnetic field It can be seen that the method of correcting to 1 can minimize the number of parameters and is rational.

Therefore, in the present invention, as described below, the wires 12 are based on the distribution of the current that is analytically guaranteed to generate a multipole magnetic field.
And the direction of the current are determined so as to obtain the magnetic field of equation (4 ').

18 and 19 show examples of analytic current distributions of 4-pole and 6-pole magnetic fields. In these figures, the black circles ● the good white circles ○ represent the currents that are in opposite directions and extend infinitely in the direction perpendicular to the paper surface, and the current I at the angle θ for generating a 2n-pole magnetic field inside is I ( θ) = kcosnθ (5) Where θ is an angle measured from the x-axis on the x, y plane, and k is a constant.

However, in the superconducting deflection magnet for the small electron storage ring, the beam line for radiating emitted light is connected to the vacuum chamber and extends in the connecting direction of the charged particle beam.
It is impossible to wind a coil with the current distribution shown in Figs. Therefore, by disposing the deforming coils for generating the 4-pole and 6-pole magnetic fields schematically shown in FIG. 20 and FIG. A predetermined multipole magnetic field was generated.

The above is the principle of the present invention. However, in order to accurately determine the arrangement of the wires capable of generating the desired magnetic field and the direction of the current, further optimization using a computer is necessary. That is, the deforming coils in FIGS. 20 and 21 are assumed to be infinitely long coils, but in the deflecting magnet of the small storage ring, the radius of curvature of the electron orbit is about the same as the magnet length, so the deforming coil is deformed. The coil should be considered arcuate. Furthermore, by simply simulating the analytical current distribution in the modified coils of FIGS. 20 and 21, it is not possible to independently generate a predetermined multipole magnetic field in the uniform magnetic field space, and other multipole magnetic fields cannot be ignored. Since they occur at the same time, it is difficult to control the correction device.

Fig. 22 shows an optimization model of wire placement using a computer. The magnetic field correction coil is considered to be an axially symmetric ring-shaped coil with respect to the Z axis of the cylindrical coordinates, and the range in which the wires can be arranged is divided into k small coils so that a predetermined magnetic field is generated in the uniform magnetic field space. The current i of the small coil is optimized and the strands are arranged so as to simulate this. With such a method, it is possible to obtain the arrangement of the element wires that generate a predetermined magnetic field with sufficient accuracy. It is not necessary to consider the influence of the iron core on the magnetic field of the magnetic field correction coil. This is because the magnetic pole is strongly saturated by the exciting coil (superconducting coil), so that the relative magnetic permeability of the magnetic pole is about the same as that of air. Further, in the above-described method of optimizing the wire arrangement,
As the magnetic field created by the magnetic field correction coil in the uniform magnetic field space,
Not only a single multipole magnetic field but also a magnetic field obtained by superimposing a plurality of multipole magnetic fields, that is, a magnetic field having a fairly complicated distribution shape is allowed as an optimization target.

As described above, a magnetic field correction coil in which the arrangement of the wires is optimized so that a magnetic field having a desired distribution shape can be generated is arranged in the gap between the magnetic pole faces, and the wires are arranged at predetermined positions at both ends of the deflection magnet. A desired correction magnetic field can be obtained in the uniform magnetic field space by connecting the element wires so that they are oriented in the same direction and exciting them.

Next, the operation of the first embodiment will be described. FIG. 5 shows an example of a method of connecting the wires 12 and the directions of the currents of the wires 12 by arrows. The magnetic field correction coil 1 shown in FIG. 5 shows a quadrupole magnetic field correction coil as an example, and the pattern of current flow is a conceptual diagram of the current distribution in the quadrupole magnetic field correction coil shown in FIG. Is the same as. The wire 12 wound in a semi-circular shape is a wire block in which current flows in the same direction.
17a to 17d, and these are connected in the same crossover pattern via crossover wires 18 in a wire connecting box 2 provided at both ends of the magnetic field correction coil 1. One of the exit lines 19 is connected to the power supply, and the other is connected to the other magnetic field correction coil 1. At this time, the upper and lower magnetic field correction coils 1 must be connected so that the directions of the currents are symmetrical with respect to the orbital plane of the charged particle beam 6. By connecting the strands 12 of the magnetic field correction coil 1 as described above, the magnetic field correction coil 1 can be excited by using one power source. In addition,
Although the magnetic field correction coil for the 6-pole magnetic field is omitted, it can be connected in the same manner as described above and can be excited by using one power source.

FIG. 6 shows the distribution of the magnetic field produced by the magnetic field correction coil 1 for the quadrupole magnetic field on the orbital plane of the charged particle beam 6. In FIG. 6, x and y are horizontal and vertical displacement coordinates from the central orbit of the charged particle beam 6 in a plane orthogonal to the orbital plane of the charged particle beam 6, and B _y is the y-direction component of the magnetic flux density. Is. By optimizing the arrangement of the strands 12, it is possible to generate a magnetic field having a linear distribution with a width of w in the x direction, that is, a quadrupole magnetic field, as shown in FIG. At this time, the magnetic field is complexly displayed inside the uniform magnetic field space 15 (see FIG. 3), and Z = x + iy, C ₂ is 4
Electrode _{B = B y + iB x =} C 2 Z ... 4 -pole magnetic field (6) is generated as the magnetic field strength. Since C ₂ is proportional to the current, it is possible to cancel the quadrupole magnetic field of desired strength in the uniform magnetic field space 15 by adjusting the current flow. However, the upper limit of the magnetic field strength that can be corrected is determined in consideration of the rise in coil temperature. Also, regarding the correction of the sextupole magnetic field, by optimizing the arrangement of the strands, a nearly ideal sextupole magnetic field is generated in the width w of the charged particle beam 6 on the orbital plane as shown in FIG. A uniform magnetic field space 15
In having a distribution of _{B = B y + iB x =} C 3 Z 2 ... (7). In this case as well, C ₃ is proportional to the energization current, so that a 6-pole magnetic field having a desired strength can be corrected by appropriately selecting the current.

It is to be noted that a multi-pole magnetic field having eight or more poles can be corrected in principle in the same manner as described above, but it is a high-order term in the error magnetic field of the deflection magnet, and its influence is small, so that its explanation is omitted. Further, in the case of simultaneously correcting a plurality of multipolar magnetic fields, the magnetic field correction coils of this embodiment may be used in combination.

According to the first embodiment, the multipole magnetic field is applied to the magnetic field correction coil 1
Since it is possible to correct the desired magnetic field using the individual power sources, there is also an effect that the structure and operation of the correction device can be simplified.

Second Embodiment In FIG. 8, the magnetic field correction coil 1 is composed of two kinds of wires 12a and 12b having different cross-sectional shapes, and a spacer 1 for adjusting the wire arrangement.
3 and reel 14 The magnetic field correction coil 1 is fixed to the magnetic pole 10 with the vacuum chamber 3 interposed therebetween, and the cross-sectional shape is symmetrical with respect to the orbital plane of the charged particle beam 6. Two
The kinds of wires 12a and 12b are independently connected in the wire connection boxes 2 provided at both ends of the magnetic field correction coil 1, and are connected to different power sources. The method of connecting the wires 12 is the same as that in FIG. In the second embodiment, the wire 12a is for correcting a quadrupole magnetic field, and the wire 12b is for correcting a sextupole magnetic field, and the positions are optimized so that these are alternately arranged. It should be noted that the disposition of the strands 12 in FIG. 8 is not necessarily accurate and is a schematic diagram. Further, the thicknesses of the wires 12a and 12b are merely examples.

Next, the configuration of the energizing device 20 for the magnetic field correction coil 1 in the second embodiment will be described in detail with reference to FIG. 9, and the operation of the second embodiment will also be described.

The energizing device 20 includes a current detector 23 for measuring the current of the exciting coil (superconducting coil) 9, an exciting pattern storage device 22 for storing the exciting pattern of each magnetic field correction coil with respect to the exciting coil current, and a measured exciting coil current value for each. A current command device 21 for determining the current value of the magnetic field correction coil and instructing the current value to the power supply of each magnetic field correction coil 21 is constituted by four-pole and six-pole magnetic field correction coil power supplies 25 and 26. Assuming that the exciting coil current measured by the current detector 23 is i, the current command device 21 causes the current i _{q of} the 4-pole magnetic field correction coil and the 6-pole magnetic field correction coil stored in advance in the excitation pattern storage device 22. Of the current i _s and the exciting coil current i, i _q = f _q (i) (8) i _s = f _s (i) (9) is used to obtain i _q and i _{s. q,} i _s current strands 12a of the magnetic field correction coil, an instruction to each power supply 25 to energize the 12b send. By the above operation, the inside of the uniform magnetic field space 15 (6)
And the 4-pole and 6-pole magnetic fields represented by the equation (7) were superposed.

B = the magnetic field _{B y + iB x = c 2} Z + c 3 Z 2 ... (10) can be generated. Where Z = x + iy, c ₂
And c ₃ are the quadrupole and sextupole magnetic field strengths, which are proportional to i _q and i _s , respectively. If k _q and k _s are proportionality constants, equation (10) can be transformed as follows.

B = B _y + iB _x = k _q f _q (i) Z + k _s f _s (i) Z ² (11) Expression (11) is a basic expression representing the operation of the second embodiment.
That is, the magnetic field represented by the equation (11) can be generated in the uniform magnetic field space 15 with respect to the exciting coil current i.

Next, in order to explain the effect of the second embodiment, the characteristics of the error magnetic field of the superconducting deflection magnet with iron magnetic poles will be briefly described.

In the deflection magnet, the exciting current is maximized when the charged particle beam 6 is accumulated, and the deflection magnetic field is also maximized. At this time, the magnetic field created by the magnetic pole 10 and the magnetic field created by the exciting coil (superconducting coil) 9 are added well, and the arrangement of the magnetic pole 10 and the exciting coil 9 is designed so as to create a uniform deflection magnetic field. However, in a state in which the exciting coil current is smaller than the value at the time of accumulation, the way of saturation of the magnetic pole 10 locally changes, so that the homogeneity of the deflection magnetic field decreases and the error magnetic field increases. The amount of such error magnetic field generated is such that the excitation rate is 40
It has been found numerically or experimentally that it becomes the maximum at ~ 50%. The second embodiment is directed to the correction of the error magnetic field that changes depending on the amount of excitation of the exciting coil.

In addition, as a method of _obtaining the functions f _q and f _{s in} the equations (8) and (9), the magnetic field distribution at each exciting coil current is measured while changing the exciting coil current in advance, and each exciting coil is based on this. The strength C ₂ and C ₃ of each multipole magnetic field is obtained by expressing the error magnetic field at the current as the sum of the multipole magnetic fields.
Next, the currents i _q and i _s of the magnetic field correction coil may be obtained using the following formula.

Here, k _q and k _s are constants determined by the shape and size of the magnetic field correction coil 1.

Figures 10 and 11 show the functions f _q and f _s obtained by the above method.
The schematic diagram of is shown. The excitation pattern storage device 22 stores these functions. Further, since it is possible to change the excitation pattern, the excitation pattern storage device 22 is provided with a data correction function.

It is possible in principle to construct a similar correction device for a multi-pole magnetic field having eight or more poles, but the explanation is omitted because the influence is small in the higher order terms.

According to the second embodiment, since the magnetic field correction coil 1 can correct the error magnetic field that changes due to the exciting current of the exciting coil, a substantially uniform deflection magnetic field is generated even if the exciting current of the exciting coil changes. There is an effect that it is possible to provide a superconducting deflection magnet that can be manufactured.

Third Embodiment In the second embodiment, the magnetic field correction coil 1 can be constructed as shown in FIG. The quadrupole magnetic field wire 12a and the sextupole magnetic field wire 12b are separated in the direction perpendicular to the orbital plane of the charged particle beam 6 to form a two-layer structure. Naturally 4
The arrangement of the pole and sextupole magnetic field wires 12a and 12b may be reversed.

According to the third embodiment, the wire 12 has a two-layer structure, and when optimizing the wire position, the movable range of the wire 12 is increased as compared with the first and second embodiments. This has the effect of obtaining a more accurate arrangement of the wires 12 that generate a multipolar magnetic field.

Fourth Embodiment In the first to third embodiments, the magnetic field correction coil 1 has a magnetic pole.
Although it is arranged between the vacuum chamber 3 and the vacuum chamber 3, the magnetic field correction coil 1 may be installed on the inner wall of the vacuum chamber 3 as shown in FIG. The magnetic field correction coil 1 includes a winding frame 14 and a vacuum chamber 3
Weld to and fix.

According to the fourth embodiment, since the magnetic field correction coil 1 can be brought closer to the electron beam 6 by the thickness of the vacuum chamber 3, there is an effect that the current of the magnetic field correction coil 1 required for correction can be reduced.

Fifth Embodiment Further, as shown in FIG.
It can also be arranged in a groove provided in the. This placement method is
This is effective when there is no space for disposing the magnetic field correction coil 1 between the magnetic pole 10 and the vacuum chamber 3.

Sixth Embodiment, Seventh Embodiment In the embodiments described so far, the magnetic field correction coil 1 is based on the natural cooling system. Depending on the current flowing through the magnetic field correction coil 1, the temperature rise of the coil may become a problem. In such a case, the sixth embodiment shown in FIG.
The water-cooled magnetic field correction coil 1 described in the seventh embodiment shown in FIG. 16 may be adopted.

In the sixth embodiment shown in FIG. 15, the magnetic field correction coil 1 is indirectly cooled by the cooling pipe 28 arranged between the wires. In the seventh embodiment shown in FIG. 16, the hollow conductor 30 is used for the wire of the magnetic field correction coil 1. Inside the hollow conductor 30, a cooling water duct 29 is provided,
Since the conductor is directly cooled, a stronger correction magnetic field can be generated than the indirect cooling type magnetic field correction coil 1 of the sixth embodiment shown in FIG.

According to the sixth and seventh embodiments, the error magnetic field larger than that of the magnetic field correction coil 1 of the natural cooling system can be corrected.

〔The invention's effect〕

According to the present invention, the magnetic field correction coils provided in parallel to the opposing magnetic pole faces generate a magnetic field that cancels out the non-uniform magnetic field of the deflection magnetic field by the particle acceleration deflection magnet to set the deflection magnetic field to a predetermined value. There is the effect of maintaining the following uniformity, and this effect has the effect of reducing the instability of the charged particle beam during accumulation of the charged particle beam and increasing the accumulation life of the charged particle beam, thus reducing the low magnetic field. Since it is possible to generate a nearly uniform deflection magnetic field up to the maximum magnetic field at the time of charged particle beam storage, it is possible to shoot low energy electrons into the storage ring and accelerate the electrons to the energy at the time of storage in the ring. There is also an effect that the system can be simplified and the cost can be reduced because the electron injection device can be downsized by this operation method.

Further, the magnetic field correction coil according to the present invention can significantly reduce the amount of the error magnetic field in the deflection magnet, so that the number of correction multipole magnets can be reduced.

[Brief description of drawings]

1 is a sectional view of a deflection magnet, which is a sectional view taken along the line AA of FIG. 2, FIG. 2 is a plan view showing a first embodiment of the present invention, and FIG. 3 is a portion of FIG. 1 showing a magnetic field correction coil. Enlarged view, Fig. 4 is a mounting view of the magnetic field correction coil, Fig. 5 is a wire connection diagram, and Fig. 6
Fig. 7 and Fig. 7 are magnetic field distribution diagrams, Fig. 8 is a sectional view showing a second embodiment of the present invention, and Fig. 9 is a block diagram of an energizing device, and Fig. 10
FIG. 11, FIG. 11 is an operation explanatory view of FIG. 8, FIGS. 12 to 16 are sectional views showing third to seventh embodiments of the present invention, and FIGS. 17 to 22 show the principle of the present invention. It is an explanatory view shown. 1 ... Magnetic field correction coil, 3 ... Vacuum chamber, 6 ... Charged particle beam, 8 ... Iron core, 9 ... Excitation coil, 10 ...
Magnetic pole, 12 ... strand, 20 ... energizing device.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shunji Kakiuchi 3-1-1, Saiwaicho, Hitachi-shi, Ibaraki Hitachi Ltd. Hitachi Factory (72) Inventor Naoki Maki 4026 Kuji-cho, Hitachi-shi, Ibaraki Hitachi, Ltd., Hitachi Research Laboratory (72) Inventor, Koji Kobayashi, 4026 Kujimachi, Hitachi City, Ibaraki Prefecture Hitachi, Ltd., Hitachi Research Laboratory (72) Inventor, Kiyoshi Yamaguchi, 4026, Kuji Town, Hitachi City, Ibaraki Hitachi, Ltd., Hitachi Research Institute ( 72) Inventor Hiroshi Tomooku 4026 Kuji-machi, Hitachi City, Ibaraki Prefecture Hitachi Research Laboratory, Hitachi, Ltd. (72) Inventor Masayuki Nakajima 3-1, Morinosato Wakamiya, Atsugi City, Kanagawa Nisshin Telegraph & Telephone Corporation (72) Inventor Teruo Hosokawa 3-1, Morinosato Wakamiya Morinosato Wakamiya, Atsugi City, Kanagawa Japan Telegraph and Telephone Stock Association In Atsugi Research Institute of Electrical Communication (72) inventor Uno Atsugi City, Kanagawa Prefecture Yasumichi Morinosatowakamiya third No. 1 Date this Telegraph and Telephone Corporation Atsugi Research Institute of Electrical Communication within

Claims (11)

(57) [Claims] 1. An iron core having a substantially fan-shaped or semi-circular horizontal cross section which has a magnetic pole facing each other and a vacuum cup for accumulating a charged particle beam is installed between the magnetic poles facing each other. And a pair of upper and lower exciting coils for generating a deflection magnetic field in the gear between the magnetic poles of the iron core, a magnetic field correction coil is arranged so as to sandwich the vacuum chamber on each of the magnetic pole surfaces facing each other of the iron core. Deflection magnet characterized by having done. 2. The deflection magnet according to claim 1, wherein the magnetic field correction coil is composed of wires that individually generate predetermined multipole magnetic fields. 3. The deflection magnet according to claim 2, wherein the wires for individually generating the predetermined multipole magnetic fields are arranged on the same plane. 4. The wires for individually generating the predetermined multipolar magnetic fields are formed by stacking wires that are independently arranged according to the magnetic field. The deflection magnet according to the second item. 5. The magnetic field correction coil comprises a plurality of strands wound around a winding frame and a spacer for adjusting the arrangement of the strands. Deflection magnet according to item. 6. The deflection magnet according to claim 2 or 5, characterized in that the wire has a built-in cooling duct. 7. The deflection magnet according to claim 2, further comprising a cooling pipe for cooling the wire. 8. A deflection magnet according to claim 1, wherein said magnetic field correction coil is attached in close contact with each of said opposing magnetic pole surfaces. 9. The deflection magnet according to claim 1, wherein the magnetic field correction coil is installed in a premises provided on each of the facing magnetic pole surfaces. 10. The deflection magnet according to claim 1, wherein the magnetic field correction coil is arranged in the vacuum chamber. 11. An iron core having a substantially fan-shaped or semi-circular horizontal cross section which has a magnetic pole facing each other inside and which forms a gear in which a vacuum chamber for accumulating a charged particle beam is installed between the magnetic poles facing each other. And a pair of upper and lower exciting coils for generating a deflection magnetic field in the gap between the magnetic poles of the iron core, an exciting coil power source for supplying a current to the exciting coil, and the vacuum chimbars on the facing magnetic pole faces of the iron core. A magnetic field correction coil installed so as to sandwich it, a magnetic field correction coil power supply for supplying a current to the magnetic field correction coil, a current detector for detecting the current of the exciting coil, a current value detected by the current detector, and A storage device that stores the excitation pattern of the magnetic field correction coil for this current value, and the magnetic field based on the detected current value of the excitation coil and the storage data of the storage device. Determining the current value of the correction coils,
An exciter for a deflection magnet, comprising: a current command device that commands the magnetic field correction coil power supply to supply a current value to the magnetic field correction coil.