JPH01282499A - Deflected electromagnet for charged-particle device - Google Patents

Abstract

PURPOSE:To realize the reduction of a magnetic loss and a leaking magnetic field under a high magnetic field, by forming a return yoke in an inflected arc shape and by providing a protruding part of the yoke. CONSTITUTION:A return yoke 1 inflects in an arc shape, on the whole, and forms an aperture 3 also in an arc shape, and moreover an inner side of the inflected yoke inflects again to an opposite direction to that of the overall yoke to form a protruding part 4. With this structure, the return yoke 1 is able to obtain a larger effective thickness than that determined by the curvature of the aperture 3, by an effect of the protruding part 4. Therewith, without increasing a size of an electromagnet significantly, a magnetic loss and a leaking magnetic field under a high magnetic field can be diminished, and the effective thickness of the yoke can be adjusted with the degree of protrusion and a shape of inflection of the part 4.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a deflecting electromagnet for a charged particle device used to bend the traveling direction of charged particles, and in particular to improvements in the yoke portion thereof.

[Prior Art] Conventional bending electromagnets for charged particle devices of this type include those shown in FIGS. 3 and 4, for example. FIG. 3 shows the bending electromagnet viewed from above, and FIG. 4 shows a sectional view taken along line IV-IV in FIG.

The bending electromagnet shown in the figure is, for example, described in the document rINS-NUM.
A-24Field Measurement o
f Dipole Magnets for TR
As shown in ANJ p36.37, (1)
is a return yoke, (2) is a coil, and (3) is an aperture.

The return yoke (1) is made of a magnetically conductive material such as iron, and is entirely curved to form an arcuate aperture (3).

In the bending electromagnet configured as described above, the magnetic field generated by the coil (2) is transmitted through the aperture (
3). The charged particles that have entered the aperture (3) pass through the aperture (3) while their traveling direction is bent by the Lorentz force acting between the magnetic field and the charged particles. Thereby, the charged particles can be deflected along the curved direction of the aperture (3).

The shape of the return yoke (1) is determined by the desired deflection angle.

For example, in order to obtain a deflection angle of 180 degrees, a return yoke (1) whose entire shape is curved at 180 degrees is used, as shown in FIG.

By the way, in this type of deflection electromagnet, the magnitude of the magnetic field to be focused on the aperture (3) must be determined depending on the beam intensity and deflection angle of the charged particles. If the beam of charged particles is strong or the deflection angle is deep,
It is necessary to focus a correspondingly high magnetic field onto the aperture (3).

When focusing a high magnetic field on the aperture (3),
It is required to reduce magnetic field loss and leakage magnetic field in the return yoke (1). For this purpose,
It is necessary to increase the magnetic field level at which the return yoke (1) is magnetically saturated, that is, the magnetic saturation level. In order to increase the magnetic saturation level, the thickness W of the return yoke (1) must be
needs to be as large as possible.

[The problem that the invention seeks to solve, XU] However,
As shown in Fig. 3, in the conventional bending electromagnet for charged particle devices, the entire return yoke (1) is connected to the aperture (3).
Since the return yoke (1) was formed in accordance with the curved shape of the return yoke (1), the thickness W of the return yoke (1) was never larger than the radius of curvature Wmax on the inner peripheral side of the aperture (3). In other words, the thickness W of the return yoke (1) is equal to the aperture (
It was defined by the curvature of 3).

Therefore, the magnetic saturation level of the return yoke (1) is limited by the curvature of the aperture (3), and when the magnetic field is high or the deflection angle is deep, it becomes impossible to prevent increases in magnetic loss and leakage magnetic field. was there.

In order to solve the above-mentioned problem, it is conceivable to make the radius of curvature WBx on the inner peripheral side of the aperture (3) sufficiently large. However, increasing the radius of curvature WIllaX on the inner peripheral side of the aperture (3) means increasing the radius of curvature of the return yoke (1), that is, increasing its size. In other words, in order to deflect charged particles in an intense beam using a high magnetic field, another problem arises: the deflection electromagnet must be significantly larger in order to reduce magnetic loss and leakage magnetic field under the high magnetic field. arise.

The present invention has been made to solve such problems, and its purpose is to obtain a bending electromagnet for charged particle devices that has less magnetic loss and less magnetic field leakage under high magnetic fields without significantly increasing the size of the electromagnet. .

[Means for Solving the Problems] A bending electromagnet for a charged particle device according to the present invention is curved in an arc shape as a whole to form an aperture curved in an arc shape, and the inner part of the curve is formed as a whole. What is the purpose of the return yoke that is curved and protruded in the opposite direction to the curve direction of the return yoke?

[Function] With the above means, the effective thickness of the return yoke can be made larger than the thickness defined by the curvature of the aperture, so it is possible to handle high magnetic fields without significantly increasing the overall external size of the electromagnet. It is possible to obtain a deflecting electromagnet for a charged particle device with less magnetic loss and leakage magnetic field underneath.

[Example] Embodiments of the present invention will be described below based on the drawings.

In the figures, parts that are the same as or correspond to the conventional ones are indicated by the same reference numerals.

FIG. 1 shows the main parts of a deflecting electromagnet for a charged particle device according to a first embodiment of the present invention.

In the figure, (1) is a return yoke, (2) is a coil, and (3) is an aperture.

Here, the return yoke (1) has an aperture (3) that is bent in an arc shape by curving the whole in an arc shape.
, and its curve protrudes in a direction opposite to the overall curve direction. (4) shows the protruding portion.

The return yoke (1) formed as described above has its effective thickness reduced by the curvature of the aperture (3) without increasing the radius of curvature of the aperture (3). The thickness can be made larger than the specified thickness.

This makes it possible to obtain a bending electromagnet for a charged particle device with less magnetic loss and less magnetic field under a high magnetic field without significantly increasing the size of the electromagnet.

In addition, the effective thickness of the return yoke (1) increased by the starting part (4) can be arbitrarily selected and adjusted depending on the size of the protrusion and the shape of the curve of the protruding part (4). can do.

FIG. 2 shows the main part of another embodiment of the present invention, in which the charged particle deflection angle of 180 degrees is obtained by curving the entire return yoke (1) by 180 degrees. At the same time, there is a protruding part (4
), the effective thickness of the return yoke (1) is significantly increased.

As a result, as in the case of the first embodiment, it is possible to obtain a bending electromagnet for a charged particle device with less magnetic loss and less magnetic field leakage under a high magnetic field without unnecessarily increasing the size of the electromagnet. It has become.

[Effects of the Invention] As explained hereinafter, in order to form an aperture curved in a circular arc, the present invention is curved in an arc shape as a whole, and the inner part of the curve is opposite to the direction of the entire curve. The structure of the return yoke, which is formed by protruding in a curved direction, makes it possible to make the effective thickness of the return yoke larger than the thickness defined by the curvature of the aperture. Load 7, which has low magnetic loss and leakage magnetic field under high magnetic fields without significantly increasing the external size, is suitable for particle devices (-
This has the effect of making it possible to obtain a magnet in the opposite direction.

[Brief explanation of the drawing]

FIG. 1 is a top view showing the main parts of a bending electromagnet for a charged particle device according to a first embodiment of the invention, and FIG. 2 shows the main parts of a bending electromagnet for a charged particle device according to a second embodiment of the invention. 3 is a top view showing a first configuration example of a conventional bending electromagnet for a charged particle device, and FIG. 4 is a top view showing IV-I in FIG. 3.
A cross-sectional view of the V portion and FIG. 5 are top views showing a first configuration example of a conventional bending electromagnet for a charged particle device. In the figure, (1) is the return yoke, (2) is the coil, and (3)
is an aperture, and (4) is a protruding portion. In addition, in the figures, the same reference numerals indicate the same or equivalent parts. Agent: Patent attorney Masuo Oiwa (and 2 others)

Claims (1)

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a deflection electromagnet for a charged particle device used for bending the traveling direction of charged particles, and in particular to improvements in the yoke portion thereof. The return yoke is formed by being curved in an arc shape as a whole to form an arc-shaped aperture, and the inner part of the curve is curved and protrudes in a direction opposite to the direction of the entire curve. A bending electromagnet for a charged particle device characterized by: