CN204518206U - The non-linear magnet of the dizzy process of a kind of permanent magnetism bundle - Google Patents

Abstract

The utility model belongs to the design technology of accelerators, in particular to a beam halo processing nonlinear magnet for accelerators. Its structure includes four magnetic poles arranged opposite to each other, and each magnetic pole is provided with a magnetic field excitation assembly, wherein, a pair of shielding magnetic poles is arranged in the middle of the four magnetic poles, and the pole heads of the shielding magnetic poles are planes. The generated magnetic field is a zero field area, and the magnetic field generated by the pole heads of four magnetic poles is a linear focus area or a nonlinear focus area; the magnetic field excitation assembly includes a permanent magnet as the main magnetic field excitation and an excitation wire package as the auxiliary magnetic field excitation . The magnet provided by the utility model can produce a large range of zero field area and focusing field strength, thereby overcoming the current beam halo processing problem, making the low-density particles on the edge focus and superimposed on the high-density particles in the center, avoiding beam halo Adverse effects of halo particles.

Description

A Nonlinear Magnet Treated by Permanent Magnet Beam Halo

technical field

The utility model belongs to the design technology of accelerators, in particular to a non-linear magnet treated with a permanent magnetic beam halo for an accelerator.

Background technique

The particle distribution of the transverse section (beam spot) of the beam generated by the accelerator is generally Gaussian distribution, that is, the distribution of particles bombarded on the target is not uniform. Gaussian distribution of the beam spot will have a small area of high-density beam nucleus and a large area of low-density beam halo around the beam nucleus. For particles with medium and low energies, beam halo particles can be directly blocked by a collimator, but after acceleration and transmission, new beam halo particles will be generated. For high-energy particles, after the beam halo particles bombard the collimator and beam pipe, a large radiation dose will be generated, resulting in the activation of matter. Therefore, accelerator beam halo handling is a very important issue.

At present, the treatment of beam halo both at home and abroad adopts the method of collimator, and the problem of activation is difficult to solve fundamentally.

Utility model content

The purpose of the utility model is to aim at the defects of the prior art, to provide a permanent magnetic beam halo treatment nonlinear magnet, which can focus the beam halo particles, so that the low-density particles at the edge can be focused and superimposed on the high-density particles at the center, and the beam halo particles can be avoided adverse effects.

The technical scheme of the utility model is as follows, a permanent magnetic beam halo treatment nonlinear magnet, including four magnetic poles arranged oppositely, each magnetic pole is provided with a magnetic field excitation assembly, wherein, a pair of shielding is provided at the middle position of the four magnetic poles The magnetic pole, the pole head of the shielded magnetic pole is a plane, and the magnetic field generated by the plane pole head is a zero field region; the magnetic field excitation assembly includes a permanent magnet as a main magnetic field excitation and an excitation wire package as an auxiliary magnetic field excitation.

Furthermore, the permanent magnetic beam halo processing nonlinear magnet as described above, wherein, the pole heads of the four magnetic poles are hyperboloid or other curved surfaces.

Furthermore, the permanent magnetic beam halo processing nonlinear magnet described above, wherein, the magnetic field generated by the pole heads of the four magnetic poles is a linear focus area or a nonlinear focus area.

Further, the above-mentioned permanent magnet beam halo treatment nonlinear magnet, wherein, the excitation coil as the auxiliary magnetic field excitation is to adjust the magnetic field excited by the permanent magnet as the main magnetic field excitation in a small range; in the permanent magnet When the excited magnetic field does not need to be adjusted, the excitation wire package as the auxiliary magnetic field excitation can be cancelled.

Further, the above-mentioned permanent magnetic beam halo processing nonlinear magnet, wherein, the permanent magnet as the main magnetic field excitation is arranged in the pole core, and other parts of the pole core except the permanent magnet are used for magnetic conduction Soft magnetic material; the excitation coil used as the auxiliary magnetic field excitation is arranged on the outside of the magnetic pole core.

The beneficial effects of the utility model are as follows: the magnetic field zero field area produced by the pole head of the shielding magnetic pole of the utility model does not affect the particle movement, and the magnetic field focusing area produced by the pole heads of the four magnetic poles focuses the beam halo particles, thereby making The low-density particles at the edge are focused and superimposed to the high-density particles at the center, avoiding the adverse effects of beam halo particles.

Description of drawings

Fig. 1 is a structural schematic diagram of a quarter part of the whole magnet structure in a specific embodiment of the present invention;

Fig. 2 is the magnetic field distribution schematic diagram (shown as half of the magnetic field distribution) on the X axis in the specific embodiment of the utility model;

Fig. 3 is an example magnetic field distribution diagram for processing beam halo particles in a specific embodiment of the present invention.

Detailed ways

Below in conjunction with accompanying drawing and embodiment the utility model is described in detail.

The utility model is an improvement on the basis of the quadrupole magnet adopted by the accelerator. The original quadrupole magnet includes four magnetic poles 1 arranged oppositely in pairs, and each magnetic pole is provided with an excitation wire package 3 and is fed with an excitation current. , as shown in Figure 1, which is a quarter of the entire magnet, and the whole figure is symmetrical about the X-coordinate axis and the Y-coordinate axis. The utility model adds a pair of shielding magnetic poles 2 at the middle positions of the four magnetic poles, and the pole head is a plane, so that the magnetic field generated by it is a zero field area 4 . The pole head surface of the original quadrupole magnet pole 1 is a hyperboloid, such as the curved surface formed by the stretching of the (xa)*y=b curve along the Z-axis direction, and a and b are constants greater than zero; they can also be designed as required For other curved surfaces, such as 3(xa) ² *yy ³ =b, the curved surface formed by stretching the curve along the Z-axis direction, a and b are constants greater than zero. The magnetic field generated by the magnetic poles is a linear focus area 5 (it can also be designed as other non-linear focus areas according to needs), and the zero field area 4 has no influence on particle motion, and the linear focus area 5 focuses the beam halo particles, so that the edge is low Density particles focus superimposed to the center of high-density particles, avoiding the adverse effects of beam halo particles.

In addition, the utility model adopts the permanent magnet 6 as the main magnetic field excitation and the excitation wire package 3 as the auxiliary magnetic field excitation for the magnetic field excitation of the magnetic poles. The main magnetic field excitation refers to the main bearer of the magnetic field excitation. Its material is a permanent magnet 6, and its position can be placed in any appropriate position in the magnetic pole core, as long as it can stimulate the required magnetic field distribution. Others in the iron core Part of it is soft magnetic material, which is used for the magnetic conduction of the magnetic circuit; the auxiliary magnetic field excitation is used to excite the magnetic field component required to adjust the magnetic field size, and is controlled by the current flowing into the excitation wire package. If the magnetic field excited by the main magnetic field excitation does not need Adjustment, the auxiliary magnetic field excitation can be canceled.

When performing beam halo treatment, it is first necessary to make the beam cross section into a very flat beam. For example, using a traditional quadrupole magnet to focus the beam spot in the Y direction and expand the beam in the X direction, so that the beam in the X direction The spot is very large, but the beam spot in the Y direction is very small. This processing method is most suitable before the beam hits the target. The Gaussian distribution curve in Figure 3 is the particle density distribution of this beam on the X-axis. Analogous to the results in Figure 2, the ABC line in Figure 3 is the magnetic field distribution on the X-axis. Wherein the AB interval is the beam core part of the beam, and the beam halo part is outside the AB interval. Under the action of this magnetic field, the particle density in the AB interval is constant, and the particles outside the AB interval are subjected to linear focusing force, and the particles at points A and B do not move, and the particles farther away from points A and B receive more focusing force. big. After drifting for a certain distance, the beam halo particles will be superimposed into the beam core, thus avoiding the collimation and cutting of the beam halo particles.

It can be seen from the characteristics of the quadrupole magnet that the beam tends to be defocused in the Y direction when it is focused and stacked in the X direction. However, since the beam is very flat, the defocusing force in the Y direction is very weak and can be ignored.

Obviously, those skilled in the art can make various changes and modifications to the utility model without departing from the spirit and scope of the utility model. In this way, if these modifications and variations of the present utility model fall within the scope of the claims of the utility model and equivalent technologies, the utility model is also intended to include these modifications and variations.

Claims (5)

1. the non-linear magnet of the dizzy process of permanent magnetism bundle, comprise four magnetic poles (1) be oppositely arranged between two, each magnetic pole is provided with magnetic field excitation component outside (1), it is characterized in that: be provided with a pair shaded pole (2) in the centre position of four magnetic poles (1), the cartridge of described shaded pole (2) is plane, and the magnetic field that plane cartridge produces is null field (4); Described magnetic field excitation component comprises the permanent magnet (6) as main field excitation and the excitation wire bag (3) as auxiliary magnetic field excitation.

2. the non-linear magnet of the dizzy process of permanent magnetism bundle as claimed in claim 1, is characterized in that: the cartridge of four described magnetic poles (1) is hyperboloid or other curved surface.

3. the non-linear magnet of the dizzy process of permanent magnetism bundle as claimed in claim 2, is characterized in that: the magnetic field that the cartridge of four described magnetic poles (1) produces is line focus district (5) or non-linear focused district.

4. the non-linear magnet of the dizzy process of permanent magnetism bundle as claimed in claim 1, is characterized in that: the described excitation wire bag (3) as auxiliary magnetic field excitation adjusts among a small circle the magnetic field of permanent magnet (6) the institute excitation as main field excitation; When not needing adjustment in the magnetic field of described permanent magnet (6) institute excitation, the described excitation wire bag (3) as auxiliary magnetic field excitation can be cancelled.

5. the non-linear magnet of the dizzy process of permanent magnetism bundle as claimed in claim 1, it is characterized in that: the described permanent magnet as main field excitation (6) is arranged in pole core, and the other parts in pole core except permanent magnet are the soft magnetic material for magnetic conduction; The described excitation wire bag (3) as auxiliary magnetic field excitation is arranged on the outside of pole core.