JPH0315320B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic field generator for a ring cyclotron.

Generally, in this type of magnetic field generator for a ring cyclotron, a plurality of dipole magnets each having a substantially C-shaped cross section are arranged radially such that their magnetic pole spaces face each other to form a space for accelerating particles. Also,
A pair of main coils are wound around the magnetic poles of each magnet. In this case, the main coil wound around each magnetic pole must be wound so as not to come into contact with other magnets or the main coil in space. Therefore, it is desirable that the lamination (that is, the width) in the direction in which the space of each main coil is narrowed (herein referred to as the width direction) is as thin as possible. In other words, when considering the space constraints defined at the center of the magnet arrangement of the ring cyclotron, it is preferable that the width of each main coil be thin.

On the other hand, the magnetomotive force of the magnetic field generator depends on the cross-sectional area determined by the width and height of each main coil.
As mentioned above, when the width of the main coil is made thinner,
If there is no change in the magnetomotive force, it is necessary to increase the height of the main coil. This means that the main coil winding portion of the magnetic pole becomes longer (higher). However, when the main coil winding portion of the magnetic pole is lengthened, the magnetic path length between the yoke and the magnetic pole becomes relatively long.
Therefore, the weight of the yoke inevitably increases depending on the length of the magnetic path.

Generally, the total weight of a magnetic field generator for a ring cyclotron is usually several hundred tons to several thousand tons, so reducing the weight of the yoke is a serious problem that cannot be ignored from an economic standpoint.

An object of the present invention is to provide a magnetic field generator for a ring cyclotron, which allows the use of a relatively small and light yoke under a given excitation power.

According to the present invention, in a magnetic field generator for a ring cyclotron, in which a plurality of magnets having a substantially C-shaped cross section are arranged radially so that the magnetic pole spaces face each other, and a main coil is wound around each magnetic pole part, adjacent A magnetic field generator for a ring cyclotron is obtained in which the cross-sectional shape of the main coil located close to the main coil of the magnet is different from the cross-sectional shape of the space side inside each yoke. Specifically, the main coil has a first width at the opening end side of the C-shaped yoke, which is determined by the first width and the magnetomotive force, and is generally much larger than the first width dimension.
The yoke has a second width larger than the first width and a second height smaller than the first height on the inner space side of the yoke. With this configuration, the width of the main coil on the open end side of the C-shaped yoke is thinner than the internal space of the yoke, so it does not come into contact with other magnet main coils, and
By selecting the cross-sectional shape of the main coil on the inner space side of the C-shaped yoke, the weight of the yoke can be kept to a minimum.

This will be explained below with reference to the drawings.

Referring to FIGS. 1 and 2, the magnetic field generator for a ring cyclotron to which the present invention is applied is equipped with a plurality of (four in FIG. 1) magnet yokes, and the magnet is a substantially C-shaped magnet. It consists of a net yoke 10, a magnetic pole 14, and a main coil 15. As shown in Figure 1, there is a space 1 necessary for the incidence of accelerated particles in the center of the four magnets.
1 is defined, and two acceleration high-frequency electrodes 12 are installed between two adjacent rows 10.

Further, as shown in FIG. 2, the magnet has a pair of magnetic poles 14 facing each other with an air gap in between, and a yoke portion extending from the magnetic poles 14 in a substantially C-shaped cross section. An internal space 13 is provided so as to be continuous with the air gap on the back side of the magnetic pole.
A main coil 15 is wound around each magnetic pole 14 .

In this configuration, the main coil 15 of each yoke 10 must be wound so as not to come into contact with the main coil of another yoke, the high frequency electrode 12, etc.
Therefore, it is desirable that the width of the main coil 15 on the space 11 side is thin. However, since the excitation power is determined by the cross-sectional area of the main coil 15, in order to maintain the excitation power, it is necessary to increase the vertical dimensions of the magnetic pole and yoke shown in FIG. For this reason,
Conventionally, a method has been adopted in which the dimensions of the magnetic pole portion are increased.

The present invention will be explained in principle with reference to FIG. In FIG. 3, it is assumed that the cross-sectional area A of the main coil 15 wound around each magnetic pole 14 is equal to each other on the space 11 side and the internal space 13 side of each magnetic pole portion. In this case, if the width and height of the main coil 15 are b and h, respectively, then the cross-sectional area A is bh
It can be expressed by.

Here, in order to reduce the weight of the yoke 10, the volumes of the yoke and magnetic pole regions (hatched portions) defined in relation to the two main coils may be minimized. Note that the cross-sectional areas of the yoke and the magnetic pole in the direction perpendicular to the magnetic path are constant. As is clear from the figure, there are two upper and lower regions 21 and 22 of the yoke 10 that are determined by the width b of the main coil 15, and four regions 23 and 2 that depend on the height h of the main coil 15.
There are 4, 25, 26. Therefore, to make the magnet as light as possible, the hatched area 21
It is nothing but the minimization of ~26. In other words, 2b+4h=2b+(4A/b)...(1) should be minimized.

The minimum value of equation (1) is b=√2=2h...(2) is given by

As can be understood from equation (2), by making the width b of the main coil 15 twice its height h, the area of the hatched regions 21 to 26 can be minimized, and the weight of the yoke 10 can therefore be reduced. It can be made the lightest. However, as described above, it is not desirable to determine the cross-sectional shape of the main coil located in the outer space 11 using equation (2).

In the present invention, in consideration of the above points, the external space 1
Cross-sectional shape and internal space 1 of main coil 15 on side 1
The cross-sectional shape of the main coil on the third side is changed to reduce the weight of the magnet and to make the protrusion of the main coil into the external space 11 as small as possible.

Referring to FIG. 4, the main coil 15 according to an embodiment of the present invention is wound in 6 layers and 2 rows on the outer space 11 side, and wound in 3 layers and 4 rows on the inner space 13 side. . Therefore, a rewinding portion 30 is provided in a part of the main coil 15 at an intermediate portion between the outer space 11 side and the inner space 13 side of the main coil 15. In this example, among the six layers and two rows of main coils 15 arranged on the outer space 11 side, the upper half of the main coils 15 is re-wound and rearranged into three layers and four rows.

Referring to FIG. 5, the main coil 15 according to another embodiment of the present invention is wound in four layers and two rows on the outer space 11 side, and in two layers and four rows on the inner space 13 side. Moreover, the width b is thinner on the outer space 11 side, and contact with other main coils can be prevented on the outer space 11 side. Therefore, this embodiment can meet the requirements for a magnetic field generator for a ring cyclotron without increasing the weight of the yoke. In addition, in the illustrated main coil 15,
Similar to FIG. 4, the upper half of the coils on the outer space 11 side are re-wound and rearranged in two layers and four rows on the inner space 13 side.

In a ring cyclotron, the weight of the main coil is around 1/100 of the weight of the yoke, and the proportion of the main coil in the weight of the entire magnetic field generator is extremely small, so the effect of reducing the yoke weight of the present invention is due to the complexity of the winding process. It cannot be compared to .

[Brief explanation of the drawing]

Fig. 1 is a diagram for explaining a magnetic field generator for a ring cyclotron to which the present invention is applied, Fig. 2 is a sectional view taken along line 2-2 in Fig. 1, and Fig. 3 is a diagram explaining the principle of the present invention. A diagram for explaining, FIG. 4 is a diagram for explaining the main coil according to an embodiment of the present invention,
and FIG. 5 are diagrams for explaining a main coil according to another embodiment of the present invention. Explanation of symbols, 10: Yoke, 11: Space outside the yoke, 12: High frequency electrode, 13: Internal space of the yoke, 14: Magnetic pole, 15: Main coil, 21~
26: Area dependent on the width and height of the main coil.

Claims (1)

[Claims] 1. A magnetic field generator for a ring cyclotron, in which a plurality of dipole magnets having a substantially C-shaped cross section are arranged radially so that the magnetic pole spaces face each other to form a circular acceleration space, and a main coil is wound around each magnetic pole part. wherein the adjacent magnets have a first cross-sectional shape having a coil width regulated from the adjacent space between the magnets at the closest position, a necessary magnetomotive force, and a coil height uniquely determined from the coil width, A ring characterized in that each of the main coils is wound so as to have a second cross-sectional shape with a coil width larger than the coil width dimension and a coil height smaller than the coil height inside the yoke curved part. Magnetic field generator for cyclotron.