JPH04334899A - Charged particle deflecting magnet - Google Patents

Abstract

PURPOSE:To adjust magnet field intensity by installing a magnetic substance for magnetic bypass adjacently to a permanent magnet. CONSTITUTION:A magnetic substance for a bypass 7 is arranged in parallel with the magnetizing direction of a permanent magnet 3. It is possible to change partially bypassing quantities of the magnet flux flowing from the magnet 3 to yoke magnetic substances 4, 5 by changing an interval G between the magnetic substance 7 and the magnet 3. The quantity of magnetic flux flowing from the magnet 3 whose magnetic flux density is constant to the magnetic substances 4, 5 is made to change so that the magnetic field intensity in a magnetic field space 6 is changed. The interval G between the magnet 3 and the magnetic substance 7 is adjusted by moving, the magnetic substance 7 by connecting a gap adjuster 8 to a moving mechanism which uses oil pressure or water pressure. Since magnetic field instensity can be changed, while the uniformity of magnetic field distribution is kept in a deflecting magnet by means of a permanent magnet, it is possible to solve such problems as high expeuse equipment of deflecting magnets acting by means of electromagnet and a high level of the running cost.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charged particle deflection magnet used in an electron cyclotron, an electron storage ring, or the like, in which charged particles are deflected by a magnetic field and accelerated and stored while being orbited.

0002

2. Description of the Related Art An acceleration/accumulation ring as schematically shown in FIG. 9 is used to accelerate or accumulate charged particles. In order to move the charged particles around the ring-shaped orbit 20, a deflecting magnet 21 is arranged as shown in FIG. 9 to bend the orbit of the charged particles. FIG. 5 shows a deflection magnet using an electromagnet, in which a beam duct 1 through which charged particles pass is placed in a magnetic field space 6 formed by the electromagnet, and the magnetic field strength given to this magnetic field space 6 is controlled by coils 22 and 23 provided in a magnetic body 24. By changing the current flowing through the magnetic field, it is possible to change the magnetic field strength while maintaining the uniformity of the magnetic field distribution. Since electromagnets can change the magnetic field strength, it can be made to correspond to changes in the energy of charged particles when they are in an accelerated state. FIG. 6 shows a deflection magnet using permanent magnets, in which permanent magnets 25 and 26 are arranged facing each other to form a magnetic field space 6 between them, and each permanent magnet 25 and 26 is connected to a yoke magnetic body 2.
7 to form a magnetic circuit. By arranging the beam duct 1 in the magnetic field space 6, it is possible to provide a constant magnetic field strength and a uniform magnetic field distribution to the charged particles. Permanent magnets cannot change the magnetic field strength, so they are suitable for situations where there is no need to change the magnetic field strength, such as when charged particles are accumulated. What is shown in Figures 7 and 8 is Japanese Patent Application Laid-Open No. 63-81798.
This is disclosed in the above publication, and uses the electromagnet mentioned above.
This is an example of a combination of a permanent magnet and a permanent magnet. An electromagnet 28 and a permanent magnet 29 are movably arranged with respect to the beam duct 1, and as shown in FIG.
Figure 8 shows a good accumulation process with a constant magnetic field strength.
The permanent magnet 29 is moved to the position of the beam duct 1 as shown in FIG.

0003

[Problems to be Solved by the Invention] In the conventional deflecting magnet described above, in the case of a deflecting magnet using an electromagnet, when the magnetic field space is 70 mm, the current to obtain a magnetic flux density of 1.2 T is approximately 50,000 ampere turns. becomes. Because there are structural limits to the number of coil turns and its cross-sectional area, it is necessary to increase the current, which requires a large-capacity power supply and a cooling device to suppress the heat generated by the coil, which solves the problem of high running costs. I'm holding it. In addition, in the case of the above-mentioned deflection magnet using permanent magnets, it is difficult to change the magnetic field strength while keeping the magnetic field distribution uniform.For example, if the magnetic field strength is changed by changing the interval between the permanent magnets that form the magnetic field, There was a problem that the uniformity of the data was lost. Furthermore, in the conventional configuration using the above electromagnet and permanent magnet,
When switching from an electromagnet to a permanent magnet, the charged particles will pass through the boundary between the electromagnet and the permanent magnet where the magnetic field distribution is not uniform, so there is a risk that the beam of charged particles will become unstable. . SUMMARY OF THE INVENTION In order to solve the above problems, it is an object of the present invention to provide a deflection magnet using a permanent magnet that can change the magnetic field strength while maintaining uniformity of the magnetic field strength.

0004

[Means for Solving the Problems] In order to achieve the above object, the present invention provides an open circuit in a magnetic closed circuit in which a yoke magnetic body is connected to a permanent magnet to form a magnetic field space, and the magnetic field direction of the magnetic field space is In a charged particle deflecting magnet in which the beam direction of charged particles is set in orthogonal directions, a magnetic bypass magnetic body is arranged adjacent to the permanent magnet in parallel to the magnetization direction of the permanent magnet, and the bypass magnetic body and permanent This is a charged particle deflection magnet characterized by being able to adjust the distance to the magnet. In addition, in a charged particle deflection magnet in which a magnetic field space is formed by providing an open circuit in a magnetic closed circuit in which a yoke magnetic body is connected to a permanent magnet, and the beam direction of the charged particles is set in a direction perpendicular to the magnetic field direction of the magnetic field space, At least one of the yoke magnetic bodies
This is a charged particle deflection magnet characterized by providing adjustable gaps at certain locations.

[0005]

[Operation] According to the above configuration, by passing a beam of charged particles through a magnetic field space formed by providing an open circuit in a magnetic closed circuit formed by connecting a yoke magnetic body to a permanent magnet, the direction of the beam of charged particles can be changed. A magnetic field can be applied in orthogonal directions, and the charged particle beam can be deflected by the Lorentz force. By changing the magnetic field strength of this magnetic field space, acceleration and
In order to correspond to the energy change of charged particles during the acceleration process of the storage ring, if a magnetic bypass magnetic material is placed adjacent to the permanent magnet and parallel to the magnetization direction of the permanent magnet, a portion of the magnetic flux flowing through the magnetic closed circuit is flows into the bypass magnetic material, so by changing the distance between the bypass magnetic material and the permanent magnet, the amount of magnetic flux flowing into the bypass magnetic material can be adjusted, and the density of the magnetic flux flowing into the yoke magnetic material changes. , the magnetic field strength of the magnetic field space can be changed. However, since the interval between the open circuits forming the magnetic field space is constant, the uniformity of the magnetic field distribution does not change even if the magnetic field strength is changed. In addition, if a gap is provided in at least one part of the yoke magnetic body that forms the magnetic closed circuit, and the interval of this gap is changed, the leakage amount of the magnetic flux flowing in the magnetic closed circuit changes, and the magnetic field strength of the magnetic field space changes. can be done. However, since the open circuit interval that forms the magnetic field space is constant, the uniformity of the magnetic field distribution does not change.

[0006]

[Example] Next, specific examples will be shown to help understand the present invention. FIG. 1 shows a first embodiment of the present invention. Yoke magnetic bodies 4 and 5 are connected to both poles of permanent magnet 3, and yoke magnetic body 4 is connected to both poles of permanent magnet 3.
and 5 form an inverted C-shaped magnetic closed circuit in which an open circuit, which is a magnetic field space 6, is formed. Since the magnetic field by the permanent magnet 3 acts on the magnetic field space 6 formed by the yoke magnetic bodies 4 and 5, the beam duct 1 is arranged at the center of this magnetic field space 6. As shown in Figure 9, the beam duct 1 is configured in a ring shape so that charged particles draw an orbit.
A magnetic field is applied in a direction perpendicular to the beam direction of charged particles passing through the beam duct 1 to deflect the charged particles by Lorentz force. The magnetic field space 6 in the magnetic closed circuit configured as described above applies a magnetic field with a uniform magnetic field distribution and a constant magnetic field strength to the beam duct 1. Therefore, in order to change the magnetic field strength without impairing the uniformity of the magnetic field distribution, the bypass magnetic body 7 is arranged parallel to the magnetization direction of the permanent magnet 3, as shown in FIG. By changing the distance G between the bypass magnetic body 7 and the permanent magnet 3, the amount by which part of the magnetic flux flowing from the permanent magnet 3 to the yoke magnetic bodies 4 and 5 is bypassed can be changed. That is, the amount of magnetic flux flowing from the permanent magnet 3, which has a constant magnetic flux density, to the yoke magnetic bodies 4 and 5 is changed, and the magnetic field strength in the magnetic field space 6 is changed. The permanent magnet 3 used in the above configuration is made of a rare earth magnet such as SmCo, which has a large residual magnetism, and the yoke magnetic bodies 4, 5 and the bypass magnetic body 7 are made of sintered ferrite, which has a magnetic permeability of several hundred or more. using the body. In addition, to adjust the distance G between the permanent magnet 3 and the bypass magnetic body 7, since the bypass magnetic body 7 receives a large magnetic attraction from the permanent magnet 3, the gap adjuster 8 is adjusted using hydraulic or hydraulic pressure as shown in FIG. The bypass magnetic body 7 is moved by connecting to a moving mechanism (not shown) such as the above-mentioned moving mechanism (not shown).

[0007] In the above configuration, the change in the magnetic field strength of the magnetic field space 6 when the distance G between the bypass magnetic body 7 and the permanent magnet 3 is changed is shown in an actual measurement graph in FIG. The horizontal axis of the figure shows the magnetic field distribution in the magnetic field space 6, that is, the distribution state of the magnetic field strength in the X direction where the yoke magnetic bodies 4 and 5 shown in FIG. Since it is downward, it is negative). When the distance G between the permanent magnet 3 and the bypass magnetic body 7 is 20 cm, 0.
A maximum magnetic field of 5T is generated in space 6. Spacing G is 20cm
There is almost no change in the magnetic field strength even if the distance is greater than
The maximum length is 20 cm in the case of the above configuration. Interval G
The magnetic field strength decreases as the distance G decreases, and when the interval G is 0 cm, the magnetic field strength is 0.05T, which is 1/10 of the maximum magnetic field strength. However, in actual use, the gap G is never set to 0 cm, so the convex portion 10 of the gap adjuster 8 is configured to maintain the minimum gap G, as shown in FIG. Also, as can be seen from Figure 2,
Center position where beam duct 1 is placed (X = 0.11m
) The uniformity of the magnetic field in the vicinity shows a uniform magnetic field distribution that is not impaired even when the magnetic field strength changes. The configuration used for this measurement uses a permanent magnet 3 with a residual magnetism of approximately 1.2 T, and conforms to the size and shape conditions shown in FIG. In addition, if an electron acceleration storage ring is constructed using deflection magnets with this configuration, a relatively small injector with a ring radius of approximately 7 m, maximum beam energy of 1 GeV, and beam incident energy of 0.1 GeV is required, and the overall cost is low. It is possible to construct an acceleration storage ring. The magnetic field strength correction coil 9 shown in FIG. 1 is used to correct errors in mechanical magnetic field strength adjustment that changes the interval G, and adds a magnetic field from an auxiliary electromagnet to the magnetic field from the permanent magnet 3 to slightly correct the error. This is for making adjustments. Since it is only necessary to pass the current necessary for generating the magnetic field for correction to this magnetic field strength correction coil 9,
There is no need for a large-capacity power supply or cooling device.

FIG. 3 shows a second embodiment of the present invention. Permanent magnets 11 and 12 are arranged facing each other with an interval that forms a magnetic field space 6, and the opposite poles of the opposing poles of each permanent magnet 11 and 12 are connected by a yoke magnetic body 13 to form an inverted C-shaped magnetic closed circuit. It consists of The uniformity of the magnetic field strength and magnetic field distribution in the magnetic field space 6 is achieved in the same manner as in the configuration of the first embodiment. The magnetic field strength in this configuration is adjusted by adjusting the distance G between the bypass magnetic body 14, which is arranged parallel to the magnetization direction of each permanent magnet 11, 12, and each permanent magnet 11, 12, as shown in the figure. Ru. A gap adjuster for adjusting the distance G is not shown. FIG. 4 shows a third embodiment of the present invention. Yoke magnetic bodies 16 and 17 are connected to both poles of the permanent magnet 15, and each of these yoke magnetic bodies 16 and 1
7 and magnetic field forming yoke magnetic bodies 18 and 19 which are arranged opposite to each other with an interval that forms a magnetic field space 6 are arranged to face each other with an interval G to form a magnetic circuit. The distance G can be adjusted by moving the block formed by the permanent magnet 15 and the yoke magnetic bodies 16 and 17. Note that illustration of a gap adjuster for adjusting the distance G is omitted because it is implemented in the same manner as in the previous example. The change in magnetic field strength in the case of this configuration differs from the above two examples in that a gap G is provided in the middle of the magnetic flux from the permanent magnet 15 flowing to the magnetic field forming yoke magnetic bodies 18 and 19, and the magnetic flux flows from this gap G. The amount of magnetic flux reaching the magnetic field space 6 is adjusted by utilizing the leakage of the magnetic flux. Therefore, by adjusting the interval G, the magnetic field strength in the magnetic field space 6 can be changed. Even if the magnetic field strength of the magnetic field space 6 is changed, the uniformity of the magnetic field distribution does not change because the opposing distance between the magnetic field forming yoke magnetic bodies 18 and 19 that form the magnetic field is constant.

[0009]

[Effects of the Invention] According to the present invention described above, it is possible to change the magnetic field strength while maintaining the uniformity of the magnetic field distribution in the deflecting magnet using a permanent magnet, so the equipment cost and running cost of the deflecting magnet using an electromagnet can be reduced. can solve the problem of height. In addition, permanent magnet deflection magnets, which conventionally could only be used as deflection magnets during the charged particle accumulation process because it is difficult to change the magnetic field strength, can also be used during the acceleration process. The deflection magnet according to the present invention can realize low construction costs and low running costs when configuring acceleration and storage rings such as relatively small electron synchrotrons and electron storage rings. It can contribute to purposes such as high-performance microfabrication of semiconductor devices.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a deflection magnet according to a first embodiment of the present invention.

[Fig. 2] Measurement graph of magnetic field strength changes using the same device.

FIG. 3 is a schematic diagram of a deflection magnet according to a second embodiment of the present invention.

FIG. 4 is a schematic diagram of a deflection magnet according to a third embodiment of the present invention.

FIG. 5 is a schematic diagram of a conventional deflection magnet using an electromagnet.

FIG. 6 is a schematic diagram of a conventional deflection magnet using a permanent magnet.

[Fig. 7] A schematic diagram of a conventional example of a deflecting magnet combining an electromagnet and a permanent magnet during an acceleration process.

[Fig. 8] A schematic diagram of the accumulation process of the same as above.

[Figure 9] Schematic diagram of the acceleration/storage ring.

[Explanation of symbols]

1... Beam duct 3, 11, 12, 15... Permanent magnet 4, 5, 12, 16, 17... Yoke magnetic body 6... Magnetic field space 7, 14... Bypass magnetic body 18, 19... Yoke magnetic body for magnetic field formation ( yoke magnetic material)
G...interval

Claims (2)

[Claims] Claim 1: Charged particle deflection in which a magnetic field space is formed by providing an open circuit in a magnetic closed circuit in which a yoke magnetic body is connected to a permanent magnet, and the beam direction of the charged particles is set in a direction perpendicular to the magnetic field direction of the magnetic field space. In the magnet, a magnetic bypass magnetic body is arranged adjacent to the permanent magnet in parallel to the magnetization direction of the permanent magnet, and the distance between the bypass magnetic body and the permanent magnet is adjustable. Particle deflection magnet. [Claim 2] Charged particle deflection in which a magnetic field space is formed by providing an open circuit in a magnetic closed circuit in which a yoke magnetic body is connected to a permanent magnet, and the beam direction of the charged particles is set in a direction perpendicular to the magnetic field direction of the magnetic field space. A charged particle deflection magnet, characterized in that a gap whose interval can be adjusted is provided at least at one location of the yoke magnetic body.