JPH03190100A - Deflection magnet of acceleration ring - Google Patents

Abstract

PURPOSE:To prevent partial heat caused by swirl current loss of end part control pieces by making the end part control pieces to be mounted on the opposed end faces of the upper and lower poles sandwitching a gap part, from the solid iron being the same as that of the upper and lower poles, and mounting the pieces through insulation layer. CONSTITUTION:An end part control piece 51 is mounted on an upper pole 11 through an insulation layer 61 while an end part control piece 52 is mounted on a lower pole through an insulation layer 62. The material thereof is the same solid iron as that of the upper and lower poles. A swirl current 210 which flows along the upper and lower poles 11, 12 is blocked from flowing to the pieces 51, 52. Only the swirl current generated due to change in the magnetic field in the pieces remains so that the temperature increase is reduced to a substantialluy ignorable level.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to a synchrotron for accelerating charged particles to create high-energy particles, and in particular a high-energy synchrotron for utilizing synchrotron radiation by high-energy electrons. This invention relates to a bending electromagnet for an acceleration ring for generating electrons, which causes electrons to travel in an arc and change their direction.

[Conventional technology]

A synchrotron is a device that rotates and accelerates charged particles using bending electromagnets arranged in a circle, and has been used in research on high-energy particles as a particle accelerator particularly suitable for obtaining high-energy particles. In recent years, progress has been made in various fields to utilize high-energy electromagnetic waves generated by synchrotron radiation of high-energy electrons generated by synchrotrons. Although a synchrotron for such practical use may be relatively small-scale, it is required to be low-priced.

One of the performance requirements of a synchrotron used in various fields is that it must be able to continuously supply high-energy electrons, so it is necessary to accelerate the electrons to produce high-energy electrons. There are two types of synchrotrons: a synchrotron called an accelerating ring for obtaining high-energy electrons, and a synchrotron called a storage ring for storing high-energy electrons generated in this accelerating ring and taking them out and using them as needed.
Since a device consisting of two synchrotrons is employed and the energy value of the electrons in the storage ring needs to be kept constant, the magnetic flux generated by the bending electromagnets forming the storage ring is constant. On the other hand, since the acceleration ring periodically generates high-energy electrons and supplies them to the storage ring, the magnetic flux density of the magnetic flux generated by the bending electromagnet changes periodically in proportion to the period of high-energy generation. is necessary.

This periodically changing magnetic flux density waveform is a trapezoidal waveform consisting of three parts: a linearly rising wave front, a flat part where the value is constant after that, and a decay part after that. It is a periodic waveform with a frequency of 0.1 Hz
The frequency ranges from the very low frequencies below to those at the commercial frequency level of about 50 Hz. Accelerate electrons at the wave front of the trapezoidal waveform to generate chamber fulgy electrons, inject the high-energy electrons generated at the plateau into the storage ring, and then reduce to zero at the wave tail for the next cycle. return. By repeating such operations periodically, high-energy electrons are continuously generated and supplied.

Figure 2 is a plan view of the bending electromagnet of a conventional accelerating ring;
The figures are the same (elevation view, and Figure 4 is a side view. In these figures, the core 1 has a cross section of C as shown in Figure 4.
The upper magnetic pole 11, the lower magnetic pole 12, and these two upper and lower magnetic poles 11.
It consists of a yoke 13 that is mechanically connected. Upper magnetic pole 1
1 has an upper coil 21 inserted into the lower magnetic pole 12, and a lower coil 22 is inserted into the lower magnetic pole 12. By passing an excitation current through the excitation coil 2 consisting of the upper coil 21 and the lower coil 22, the air gap shown in FIG. A magnetic flux 100 is generated that passes through the gap 14, and the electron beam travels through an electron beam duct (not shown) that is perpendicular to the plane of the paper through the center of the gap 14. The traveling path of this electron beam is bent by the magnetic flux 100 and it draws a circular trajectory.The purpose of the bending electromagnet is to change the traveling direction of the electron beam in this way, and the synchrotron uses such a bending electromagnet. The bending electromagnet shown in the figure is actually fan-shaped to match the circular orbit of the electron beam. In these figures, straight lines are shown instead of circular arcs for simplification of illustration. Incidentally, in FIG. 2, the iron core l has a downwardly convex fan shape, and accordingly, the two long sides of the excitation coil 2 are actually circular arc shapes.

The size of the iron core l is, for example, 3 m in the length direction, which is the left and right direction in Figures 2 and 3, and 50 m in the left and right width dimension in Figure 4.
The length of the gap 14 is about 50 mm, and the width of the gap 14 is about 200 mm.

In order to accurately set the travel path of electrons, the gap 14
It is necessary that the magnetic flux distribution within the core 1 be highly accurate, and therefore the dimensions of the iron core 1 must be highly accurate.

The angle change in the traveling direction of the electron beam due to the bending electromagnet is
It is determined by the integral value along the traveling direction of the magnetic flux density component perpendicular to the electron beam, but as mentioned above, even if the bending electromagnet is manufactured with high precision, it is impossible to avoid a certain degree of error. A means is required to adjust the integral value to a predetermined value. From this point of view, the upper magnetic pole 1
1. End adjusting pieces 41, 4 are provided on both end faces of the lower magnetic pole 12.
2°43.44.45,46,47.48 are provided. The end adjustment piece 48 is the same as the end adjustment piece 46 in FIG.
In FIG. 3, they are located on the other side of the end adjustment pieces 47 and are not shown in the figure. Note that matters common to all end adjustment pieces are referred to when referring to the end adjustment pieces. 4 is used as a unified reference code.

On the end surface of the upper magnetic pole 11 shown in FIG.
2 is installed. The shape of the end adjustment piece is actually not as simple as this, and the surface shape and dimensions on the gap side are adjusted in a complicated manner in order to adjust the magnetic field distribution at the end of the bending electromagnet. In fact, the surfaces of the upper and lower magnetic poles 11, 12 facing the air gap 14 are also curved in order to obtain a predetermined magnetic field distribution. End adjustment pieces 45 and 46 are provided on the opposite end surface of the upper magnetic pole 11, and end adjustment pieces 43 and 44 are provided on the opposite end surface of the lower magnetic pole 12 as shown in FIG. End adjustment pieces 47° and 48 are attached.

As for the material of the iron core 1, since there is no quantitative change in the magnetic flux 100 in the case of the storage ring bending electromagnet, pure iron in the form of a solid lump is used, and this is machined to produce the iron core with predetermined dimensions and shape. . Pure iron here refers to iron material with a lower carbon content than ordinary carbon steel, which has so-called soft magnetic properties with low hysteresis loss, and is sometimes used as the iron core of electromagnets instead of silicon steel sheets. Because it has good workability, it is used when machining is required and an inexpensive iron core material is required.

On the other hand, in the case of accelerating rings, the magnetic flux changes over time as mentioned above, so in order to suppress eddy currents generated in the iron core due to electromagnetic induction, the same as used in rotating machines and transformers, A laminated core made of laminated silicon steel plates is used. If the dimensions and shape are the same, laminated iron cores are often more expensive, so solid pure iron is sometimes used even for bending electromagnets in acceleration rings when the influence of eddy currents is small. be. In such a case, the end adjustment piece 4
The same material as iron core 1, solid pure iron, is usually used.

[Problem to be solved by the invention]

Since the iron core 1 has a fairly large size as described above, the temperature of the iron core 1 may become excessive even if the influence of eddy currents is small. During operation, the magnetic flux is generated by excitation by the excitation coil 2, and eddy currents flow through the iron core 1 due to temporal changes in this magnetic flux, causing eddy current loss. As shown in the plan view of Figure 2,
An eddy current 200 flows in a spiral shape as shown in the figure, which attempts to cancel the magnetic flux 100 that enters at right angles toward the plane of the paper. As shown in Figure 3, the upper and lower magnetic poles 1
Eddy currents 200, 210 on the surface of 1.12 flow along the air gap 14 in the direction indicated by the arrow.

As is well known, the eddy currents 200, 210, and 220 tend to have larger values closer to the surface. Therefore, eddy currents also flow into the end adjusting pieces 4 attached to the end faces of the upper and lower magnetic poles 11 and 12, and as a result, the temperature may become higher than that of the upper and lower magnetic poles 11 and 12. In the upper and lower magnetic poles 11.12, eddy currents are small and the eddy current loss is small, so the temperature rise as a whole is not very large.
Since the eddy current is attached protruding from the upper and lower magnetic poles 11 and 12, the eddy current has a larger current density on the surface than the upper and lower magnetic poles 11 and 12, because the eddy current has a larger value on the surface as described above. Therefore, a phenomenon occurs in which the temperature becomes higher than the temperature rise value of the upper and lower magnetic poles 11 and 12. If the temperature rise value of the end adjustment piece 4 is large, internal stress will occur due to the temperature difference, causing the end adjustment piece 4 to deform or change its magnetic properties.
A problem arises in that it becomes impossible to maintain a highly accurate magnetic flux distribution.

It is an object of the present invention to solve such problems and to provide a stable deflection electromagnet for an acceleration ring that suppresses the temperature rise of the end adjusting piece due to eddy currents.

[Means to solve the problem]

In order to solve the above problems, the present invention provides a bending electromagnet for an acceleration ring, which has an iron core made of solid iron and has a C-shaped cross section, and a beam duct for passing an electron beam through a gap. An end adjusting piece is made of solid iron and is attached to both end faces perpendicular to the traveling direction of the electron beam of the upper magnetic pole and the lower magnetic pole, each of which has an excitation coil wound therebetween. are attached to both end surfaces of the lower magnetic pole and the upper magnetic pole via an insulating layer.

[Effect]

In the configuration of the present invention, the end adjustment pieces attached to both end faces perpendicular to the traveling direction of the electron beam of the upper magnetic pole and the lower magnetic pole that sandwich the air gap are made of solid iron, the same as the upper magnetic pole and the lower magnetic pole,
By attaching this via an insulating layer, the eddy current flowing from the upper M1 rod and the lower magnetic pole to the end adjustment piece is blocked, and the eddy current flowing to the end adjustment piece is limited to only that caused by the magnetic flux passing through itself. As a result, the eddy current loss of the end adjustment piece is significantly reduced, so that it is possible to prevent the end adjustment piece from locally overheating.

〔Example〕

The present invention will be explained below based on examples. FIG. 1 is an enlarged elevational view of a main part showing an embodiment of the present invention in which the end adjustment piece is attached. In this figure, the upper ifi lever 11. Parts of the lower magnetic pole 12 and exciting coil 2 are shown, but these are the same as in FIG. 3. Also, end adjustment pieces 51, 53 and end adjustment pieces 52, 54 not shown in this figure.
, 55, 5657.58 is substantially the same as the end adjustment piece 4 shown in FIGS. 2, 3, and 4 in terms of material, shape, and dimensions. End adjustment pieces 51, 52, 53.54°55.
For items common to 56, 57, and 58, 5 is used as a unified reference numeral, similar to the end adjustment piece 4 in the prior art.

As shown in the figure, the end adjusting piece 51 is attached to the upper magnetic pole 11 via an insulating layer 61, the end adjusting piece 52 is attached to the upper magnetic pole 12 via an insulating layer 62, and all the end adjusting pieces 5 is attached via the insulating layer 6. Insulating layer 6 is a uniform reference symbol for all insulating layers, including the illustrated insulating layers 61, 62.

Since the eddy currents 210 and 220 shown in FIG. 3 have the property of being generated as much as possible on the surface of the conductor, the end adjusting piece 5 is electrically integrated with the lower magnetic pole 11 and the upper magnetic pole 12 as in the conventional technology. However, since the insulating layers 61 and 62 are provided, the eddy currents 210 and 220 flow into the end adjustment pieces 51 and 52.
1.52, the eddy current 210 changes its direction and flows along the left end surface of the lower magnetic pole 11 into an eddy current 211 perpendicular to the plane of the paper as shown. Since magnetic flux also flows through the end adjustment pieces 51 and 52, eddy currents induced by temporal changes in this magnetic flux exist, and this eddy current 23
0 becomes an eddy current that reciprocates within the end adjustment piece 51 as shown in the figure. Since the magnitude of this eddy current 230 is much smaller than the current density of the eddy current 210 flowing through the lower magnetic pole 11, the temperature increase in the end adjustment piece 51 due to this eddy current 230 is substantially negligible. . Other end adjustment piece 52. The same applies to the other six end adjustment pieces 5 not shown in FIG.

By providing the insulating layer 6, the voltage that is generated between the upper and lower magnetic poles 11, 12 and the end adjustment piece 5 is a small voltage that does not exceed 1. Since it is sufficient to serve as a spacing piece to prevent metal contact between the adjustment piece 5 and the adjustment piece 5, a thickness of 11 or less is sufficient. Therefore, this insulating layer 6 does not have much influence on the magnetic flux passing through the end adjustment piece 5, and the insulating layer 6
By manufacturing the end adjusting piece 5 in advance in consideration of the existence of the above, this effect does not become a substantial problem.

It is appropriate that the end adjusting piece 5 be attached to the upper and lower magnetic poles 11, 12 by bolting. In this case, the bolts are installed in the bolt holes drilled in the upper and lower magnetic poles 11.12, and the end adjustment pieces 5 are tightened and fixed, so the bolts are installed at the same potential as the upper and lower magnetic poles 11.12. Therefore, it is necessary to insulate the bolt and the end adjustment piece during installation, but this type of installation requires insulation of the bolt, which is often used in large-capacity rotating machines and transformer core integrated structures. By using this technique, it is easy to attach the end adjustment piece 5 to the E lower magnetic pole 11, 12.

〔Effect of the invention〕

As described above, in this invention, the end adjustment pieces attached to both end faces of the upper and lower magnetic poles sandwiching the gap are made of solid iron, the same as the upper and lower magnetic poles, and the end adjustment pieces and the upper and lower magnetic poles are made of solid iron. By providing an insulating layer between them to prevent eddy current from flowing into the end adjustment piece from the upper and lower magnetic poles, the eddy current flowing through the end adjustment piece is induced by the magnetic flux passing through the end adjustment piece itself. It becomes only Since the magnitude of this eddy current is much smaller than the magnitude of the eddy current flowing from the upper and lower magnetic poles without an insulating layer, overheating of the end adjusting piece can be prevented. Therefore, thermal stress occurs due to the temperature difference between the upper and lower magnetic poles, resulting in deformation of the end adjustment piece, and changes in the magnetic properties of the end adjustment piece, resulting in disturbances in magnetic flux distribution, resulting in high accuracy. The problem of not being able to maintain the magnetic flux distribution is solved, and the end adjustment piece can perform a stable end adjustment function, resulting in a highly reliable accelerator ring bending electromagnet. You can get great results if you can.

[Brief Description of the Drawings] Fig. 1 is an elevational view of the main parts of a bending electromagnet showing an embodiment of the present invention, Fig. 2 is a plan view of a conventional bending electromagnet, Fig. 3 is an elevational view of the same, and Fig. The figure is also a side view. ...Iron core, 11...Upper magnetic rake, 12...Lower magnetic rod, 3
...Yoke, 14...Gap, 2...Exciting coil,
■... Upper coil, 22... Lower coil, 41.42.
43.44,45,46,47゜8.5.51.52・
・End adjustment piece. 3rd Figure 2 Figure 4

Claims (1)

[Claims] 1) An accelerating ring deflection electromagnet with an iron core made of solid iron having a C-shaped cross section and a beam duct for passing an electron beam through a gap, with an excitation coil wound around each gap. The end adjusting pieces attached to both end faces of the upper magnetic pole and the lower magnetic pole perpendicular to the traveling direction of the electron beam are made of solid iron, and the end adjusting pieces are attached to the lower magnetic pole and the upper magnetic pole through an insulating layer. A bending electromagnet of an acceleration ring characterized by being attached to both end faces of the magnetic pole.