JP3868103B2 - Charged particle beam trajectory forming apparatus and operating method thereof - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a charged particle beam trajectory forming apparatus and a method for operating the charged particle beam trajectory, and more particularly to a charged particle beam trajectory forming apparatus having a field clamp for shielding a leakage magnetic field in the vicinity of an end portion of a deflecting electromagnet.
[0002]
[Prior art]
An arcuate portion of a circular orbit of a charged particle beam such as a synchrotron is defined by a deflecting electromagnet. In order to shield the magnetic field leaking from the end portion of the deflection electromagnet, a field clamp made of a magnetic material is disposed in the vicinity of the end portion. Further, a steering electromagnet for controlling the traveling direction of the charged particle beam traveling along the orbit is disposed in the other part of the orbit.
[0003]
[Problems to be solved by the invention]
In recent years, downsizing of charged particle beam orbit forming apparatuses such as synchrotrons has been desired. For this purpose, it is necessary to reduce the orbit of the charged particle beam. In the conventional apparatus, it is necessary to secure a place for arranging the steering electromagnet, which hinders downsizing.
[0004]
An object of the present invention is to provide a charged particle beam trajectory forming apparatus suitable for miniaturization and an operating method thereof.
[0005]
[Means for Solving the Problems]
According to one aspect of the present invention, a deflecting electromagnet that defines an arc-shaped trajectory of a charged particle beam and a magnetic material disposed at the end of the arc-shaped trajectory are affected by a leakage magnetic field from the deflecting electromagnet. A field clamp having a through-hole along the trajectory of the charged particle beam continuous to the arc-shaped trajectory, and exciting a dipole magnetic field perpendicular to the trajectory plane of the arc-shaped trajectory in the through-hole, the have a coil wound around the field clamp, and input and output end face of the pole of the bending electromagnet, the field and the deflection electromagnet side end face of the clamp are arranged in parallel, said field clamp deflection electromagnet the end surface of the side is, forming apparatus of the charged particle beam orbit is disposed obliquely with respect to the trajectory of the charged particle beam to be continuous with the arcuate track is provided .
[0006]
The dipole magnetic field excited in the through hole of the field clamp changes the traveling direction of the charged particle beam traveling along the orbit in the orbit plane. By adjusting the current flowing through the coil wound around the field clamp, the traveling direction of the charged particle beam can be finely adjusted.
[0007]
According to another aspect of the present invention, there is provided a method of operating the charged particle beam orbit forming apparatus, by adjusting the step of entering the charged particle beam in the arc-shaped orbit, the current applied to the coil, the There is provided a method of operating a charged particle beam trajectory forming apparatus including a step of finely adjusting a traveling direction of a charged particle beam.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1A is a cross-sectional view of a track surface of a charged particle beam trajectory forming apparatus according to an embodiment of the present invention, and FIG. 1B is a cross-sectional view taken along one-dot chain line B1-B1 of FIG. Indicates. FIG. 1A corresponds to a cross-sectional view taken along one-dot chain line A1-A1 in FIG.
[0009]
A semicircular arc-shaped track 1a is defined by a pair of magnetic poles 2 arranged opposite to each other along the semicircular arc. A vacuum vessel 5 is arranged in the gap between the pair of magnetic poles 2, and the arcuate track 1 a is arranged inside the vacuum vessel 5. Each of the pair of magnetic poles 2 is connected via a return yoke 10. The return yoke 10 crosses the raceway surface at the semicircular arc-shaped portion on the outer peripheral side of the semicircular arc-shaped track 1a and the linear portion connecting both ends thereof.
[0010]
Linear tracks 1b and 1c are connected to both ends of the arc-shaped track 1a, respectively. Through holes 11b and 11c are formed in the return yoke 10 corresponding to the linear tracks 1b and 1c. A pair of magnetic poles 2 is surrounded by main coils 15A and 15B, respectively. The main coils 15 </ b> A and 15 </ b> B are disposed along the outer peripheral surface on the outer peripheral side of the magnetic pole 2, and are disposed substantially linearly along the inner surface of the return yoke 10 on the inner peripheral side. The magnetic pole 2, the return yoke 10, and the main coils 15A and 15B constitute a deflection electromagnet.
[0011]
Field clamps 20b and 20c made of a magnetic material such as iron are disposed in the vicinity of both ends of the semicircular arc-shaped track 1a. The field clamps 20b and 20c have through holes 21b and 21c along the linear tracks 1b and 1c, respectively.
[0012]
When a direct current is passed through the main coils 15 </ b> A and 15 </ b> B, a magnetic field is excited in the closed magnetic path defined by the magnetic pole 2, the gap between the magnetic poles, and the return yoke 10. Due to this magnetic field, the charged particle beam receives a force in a direction perpendicular to its traveling direction, and travels along the semicircular arc 1a. The field clamps 20b and 20c are arranged at the positions where the influence of the leakage magnetic field from the magnetic pole 2 at both ends of the semicircular arc-shaped track 1a and shields the leakage magnetic field.
[0013]
2A is a cross-sectional view of the field clamp 20c on the raceway surface, and FIG. 2B is a cross-sectional view taken along one-dot chain line B2-B2 of FIG. FIG. 2A corresponds to a cross-sectional view taken along one-dot chain line A2-A2 in FIG. The other field clamp 20b is mirror-symmetrical with the field clamp 20c.
[0014]
The incident / exit end face of the magnetic pole 2 is processed obliquely with respect to the linear track 1c. If the angle between the image obtained by vertically projecting the end face of the magnetic pole 2 on the track surface and the plane perpendicular to the straight track 1c is θ, the angle θ is 30.7 °, for example. The through-hole 21c has a rectangular cross-sectional shape, and a pair of mutually opposed surfaces is parallel to the track surface, and the other pair of surfaces is parallel to the straight track 1c and perpendicular to the track surface. is there.
[0015]
The end face of the field clamp 20c facing the magnetic pole 2 is substantially parallel to the end face of the magnetic pole 2 and is processed obliquely with respect to the linear track 1c. The interval g along the straight track 1c between the two end faces facing each other is, for example, 10 cm. The other end face of the field clamp 20c is machined perpendicular to the linear track 1c.
[0016]
Two auxiliary coils 22A and 22B are wound so as to interlink with the field clamp 20c. Auxiliary coils 22A and 22B are disposed in portions that define a pair of surfaces perpendicular to the track surface of through-hole 21c.
[0017]
A current in a direction indicated by an arrow I is supplied to the auxiliary coils 22A and 22B, that is, a current in a direction that excites a magnetic field across the orbital plane (the paper surface of FIG. 2A) in the auxiliary coils 22A and 22B in the same direction. As shown in FIG. 2B, a magnetic field 25 interlinking with each of the auxiliary coils 22A and 22B is formed, and a dipole magnetic field substantially perpendicular to the track surface is formed in the through hole 21c.
[0018]
This dipole magnetic field changes the traveling direction of the charged particle beam traveling along the linear trajectory 1c in the trajectory plane. The traveling direction of the charged particle beam can be finely adjusted by adjusting the current flowing through the auxiliary coils 22A and 22B. That is, the field clamps 20b and 20c function as a steering magnet. For this reason, it is not necessary to secure a dedicated installation location for the steering magnet, and the track can be miniaturized.
[0019]
Although the present invention has been described with reference to the embodiments, the present invention is not limited thereto. It will be apparent to those skilled in the art that various modifications, improvements, combinations, and the like can be made.
[0020]
【The invention's effect】
As described above, according to the present invention, a coil is wound around a field clamp disposed at the entrance / exit end of a deflecting electromagnet for a charged particle beam, and a bipolar magnetic field is generated by this coil, whereby a steering magnet is attached to the field clamp. Can have a function. Since it is not necessary to secure a place for the steering magnet, it is possible to reduce the size of the charged particle beam trajectory forming apparatus.
[Brief description of the drawings]
FIG. 1 is a sectional view of a charged particle beam trajectory forming apparatus according to an embodiment of the present invention.
FIG. 2 is a cross-sectional view of a field clamp according to an embodiment of the present invention.
[Explanation of symbols]
1a Semicircular arc-shaped track 1b, 1c Linear track 2 Magnetic pole 5 Vacuum vessel 10 Return yoke 11a, 11b Through holes 15A, 15B Main coil 20a, 20b Field clamp 21 Through holes 22A, 22B Auxiliary coil 25 Magnetic field

Claims (3)

A deflection electromagnet defining an arcuate trajectory of the charged particle beam;
Arranged at a position where the influence of the leakage magnetic field from the deflecting electromagnet reaches at the end of the arcuate track, is formed of a magnetic material, and has a through-hole along the track of the charged particle beam continuous to the arcuate track A field clamp,
It said the through hole, so as to excite the vertical dipole field the raceway surface of the arcuate track, have a coil wound around the said field clamp,
The entrance / exit end face of the magnetic pole of the deflection electromagnet and the end face on the deflection electromagnet side of the field clamp are arranged in parallel, and the end face on the deflection electromagnet side of the field clamp is continuous with the arcuate track. An apparatus for forming a charged particle beam trajectory arranged obliquely with respect to the trajectory of the charged particle beam.   The charged particle beam trajectory forming apparatus according to claim 1, wherein an end surface of the feed clamp opposite to the deflection electromagnet is perpendicular to a charged particle beam trajectory. A deflecting electromagnet that defines an arcuate orbit that forms a part of the orbit of the charged particle beam, and a magnetic material that is disposed at the end of the arcuate orbit at the position affected by the leakage magnetic field from the deflecting magnet. A field clamp having a through-hole along the trajectory of the charged particle beam continuous to the arc-shaped trajectory, and exciting a dipole magnetic field perpendicular to the trajectory plane of the arc-shaped trajectory in the through-hole, the have a coil wound around the field clamp, and input and output end face of the pole of the bending electromagnet, the field and the deflection electromagnet side end face of the clamp are arranged in parallel, said field clamp deflection electromagnet the end surface of the side is, the method of operating a charged particle beam orbit forming apparatus of the charged particle beam orbit is disposed obliquely with respect to the continuing to the arcuate track There,
Injecting a charged particle beam into the arcuate trajectory;
A method of operating a charged particle beam trajectory forming apparatus, comprising: adjusting a current flowing through the coil to finely adjust a traveling direction of the charged particle beam.

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