JP2002025795A - Charged particle deflecting electromagnet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light-weight and small charged particle deflecting electromagnet, having superior linearity in an intensity change in a magnetic field space, and causing no reduction in magnetic field intensity. SOLUTION: This electromagnet has bipolar magnetic poles 2, 3 generating the magnetic field, where charged particles incident from an opening part 4 at a prescribed angle are subjected to a magnetic field which is linearly enhanced toward the inside to be deflected and is emitted from the opening part 4 again at a prescribed angle. The counter posed faces of the magnetic poles 2, 3 have a hyperbolic shape in a cross section perpendicular to an orbital plane of the charged particle, are asymmetric with respect to the center lines at ±45 degrees with respect to a plane perpendicular to the advancing direction of the charged particles, and are made smoother, the farther they go away from the opening part 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electromagnet requiring a magnetic field space whose intensity varies linearly, and more particularly to an electromagnet incorporated in a charged particle accelerator for deflecting charged particles.

[0002]

2. Description of the Related Art FIG. 5 shows a structure of a conventional charged particle bending electromagnet. 5, reference numeral 1 denotes a coil, 2 denotes an N-pole, 3 denotes an S-pole, 4 denotes an opening through which charged particles enter and exit, and 5 denotes a magnetic pole and an iron core that supports the N-pole. FIG. 6 shows the flow of magnetic flux lines in a conventional charged particle bending electromagnet.

As shown in FIG. 5, a conventional charged particle bending electromagnet has a two-pole magnetic pole shape. An electromagnet, which is generally called a quadrupole electromagnet, is divided into two about a vertical center line. . The hyperbolic shapes of the magnetic poles 2 and 3 are ±
The shape is symmetrical with respect to each center line of 45 degrees. The charged particles incident from the opening 4 are deflected in the generated magnetic field space, and exit from the opening 4 again.

FIG. 3 is an explanatory diagram showing the trajectories of charged particles. In FIG. 3, reference numeral 6 denotes charged particles. Charged particles 6
Draws a trajectory as shown in FIG.

FIG. 4 is an explanatory diagram showing a magnetic field intensity distribution in a magnetic field space. As shown in FIG. 4, in the magnetic field space for deflecting the charged particles, the magnetic field intensity linearly increases in proportion to the dimension as the opening goes to 0 and goes inward.

[0006] In the conventional charged particle bending electromagnet, the hyperbolic shape of the magnetic pole is symmetrical with respect to each center line of ± 45 degrees, and the trajectory of the charged particle alone as shown in FIG. Since a magnetic field generated in a direction other than the direction is large and the magnetic field strength is reduced, it is necessary to increase the size of the iron core, which is a return proportional to the size of the pole face, in order to maintain the required magnetic field strength. Therefore, there has been a problem that the overall weight increases and the electromagnet becomes large.

[0007]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned problems and provides a small-sized charged particle having a good linearity of the intensity change in the magnetic field space, no reduction in the magnetic field intensity, a light weight as a whole, and a small weight. It is an object to provide a bending electromagnet.

[0008]

In order to obtain a magnetic field space which becomes linearly strong, the shape of the magnetic pole is desirably hyperbolic, and even if it is not hyperbolic, the shape of the magnetic pole should be an arc and a linear approximation. Is desirable. In order to improve the linearity of the intensity change of the magnetic field, it is necessary to make the end of the hyperbola as long as possible.

Therefore, according to the present invention, the hyperbolic shape of the magnetic pole is asymmetrical with respect to each center line of ± 45 degrees, and the end of the hyperbolic line which generates the magnetic field space required for deflection is provided. Is made longer only in the direction opposite to the opening, and the end of a hyperbola extending in a direction perpendicular to the trajectory of the charged particle is shortened, so that the pole face is made as small as possible.

That is, according to the present invention, a charged particle incident at a predetermined angle from an opening is deflected by receiving a magnetic field that becomes linearly stronger as it travels inside, and is emitted again at a predetermined angle from the opening. In a charged particle deflecting electromagnet having a pair of magnetic poles in two poles that generates a magnetic field space such that the surface opposite to the magnetic pole is a cross section perpendicular to the orbital surface of the charged particle, is hyperbolic, A charged particle bending electromagnet characterized by being asymmetrical with respect to a centerline of ± 45 degrees with respect to a plane perpendicular to a direction in which charged particles travel, and being smoother as the distance from the opening increases.

As a result, the shape of the hyperbola of the magnetic pole is ± 4.
Compared with a conventional electromagnet having a symmetrical shape with respect to each center line of 5 degrees, as in the present invention, a magnetic field space in which the linearity changes satisfactorily is secured, and the magnetic field strength does not decrease. Thus, a small electromagnet having a small overall weight can be obtained.

[0012]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a cross-sectional view showing the structure of a charged particle bending electromagnet according to an embodiment of the present invention. FIG.
FIG. 1 is a cross-sectional view for explaining the flow of magnetic flux lines in a charged particle bending electromagnet according to an embodiment of the present invention.

As shown in FIG. 1, the electromagnet of the present invention has a hyperbolic magnetic pole, but has an asymmetric shape with respect to the center line of ± 45 degrees, and its end extends long in the orbital direction of the charged particles. ing.

As a result, a magnetic field space in which the linearity of the magnetic field in the orbital direction of the charged particles is good is obtained. Also, the end of the hyperbola of the magnetic pole is shorter in the direction perpendicular to the orbit,
Unnecessary magnetic fields are not generated.

In the present invention, the flow of the magnetic flux lines is as shown in FIG. Therefore, the iron core serving as the return is smaller than that of the conventional type, the overall weight is light, and a small electromagnet can be manufactured.

[0017]

As described above, according to the present invention,
It was possible to provide a small charged particle bending electromagnet having good linearity of the intensity change in the magnetic field space, no reduction in the magnetic field intensity, a light overall weight, and a small size.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing the structure of a charged particle bending electromagnet according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view illustrating the flow of magnetic flux lines in the charged particle bending electromagnet according to one embodiment of the present invention.

FIG. 3 is an explanatory diagram showing a trajectory of a charged particle.

FIG. 4 is an explanatory diagram showing a magnetic field intensity distribution in a magnetic field space.

FIG. 5 is a cross-sectional view showing the structure of a conventional charged particle bending electromagnet.

FIG. 6 is a cross-sectional view illustrating the flow of magnetic flux lines in a conventional charged particle bending electromagnet.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Coil 2 N pole magnetic pole 3 S pole magnetic pole 4 Opening 5 Iron core 6 Charged particle

Claims (1)

[Claims] 1. A magnetic field in which charged particles that enter at a predetermined angle from an opening are deflected by receiving a magnetic field that increases linearly as they travel inside, and exit again at a predetermined angle from the opening. In a charged particle bending electromagnet having a pair of magnetic poles that generate a space, a surface facing the magnetic pole has a cross section perpendicular to an orbital surface of the charged particle, has a hyperbolic shape, and the charged particle travels. A charged particle deflecting electromagnet, which is asymmetrical with respect to a center line of ± 45 degrees with respect to a plane perpendicular to the direction in which the charged particle is deflected, and becomes smoother as the distance from the opening increases.