CN104717824A

CN104717824A - Beam halo treatment nonlinear magnet for accelerator

Info

Publication number: CN104717824A
Application number: CN201410841750.1A
Authority: CN
Inventors: 李金海; 任秀艳; 曾自强
Original assignee: China Institute of Atomic of Energy
Current assignee: China Institute of Atomic of Energy
Priority date: 2014-12-30
Filing date: 2014-12-30
Publication date: 2015-06-17

Abstract

The invention belongs to accelerator design techniques, and particularly relates to a beam halo treatment nonlinear magnet for an accelerator. The beam halo treatment nonlinear magnet for the accelerator comprises four magnetic poles, every two magnetic poles are oppositely arranged, and an excitation coil is arranged outside each magnetic pole, wherein a pair of shaded poles are arranged in the middle of the four magnetic poles, the magnetic pole head of each shaded pole is a plane, magnetic fields generated by the plane magnetic pole heads are null fields, and the magnetic fields generated by the magnetic pole heads of the four magnetic poles are linear focusing areas or non-linear focusing areas. The beam halo treatment nonlinear magnet for the accelerator can generate a wider range of null field and focusing field strength, so that the current beam halo treatment problem can be overcome, low-density particles at the edges are focused and overlaid on the high-density particles of the center, and the adverse impact of beam halo particles is avoided.

Description

The non-linear magnet of the dizzy process of a kind of accelerator bundle

Technical field

The invention belongs to accelerator design technology, be specifically related to the non-linear magnet of the dizzy process of a kind of accelerator bundle.

Background technology

The distribution of particles of the line lateral cross section (bundle spot) that accelerator produces is generally Gaussian Profile, and the distribution of particles of namely bombarding on target is uneven.The bundle spot of Gaussian Profile have the highdensity bundle core of a zonule and bundle core around the low-density bundle of large regions swoon.For the particle of middle low energy, the dizzy particle of bundle directly can keep off by collimater, but afterwards through to accelerate and after transmission, can produce again new bundle and to swoon particle.For high energy particle, larger radiation dose can be produced after the dizzy particle bombardment collimater of bundle and beam current tube, cause the activation of material.Therefore, the process of swooning of accelerator bundle is a very important problem.

At present, the process that domestic and international halved tie is swooned is all the method adopting collimater, and the problem of activation is difficult to basic solution.

Summary of the invention

The object of the invention is to the defect for prior art, provide a kind of accelerator to restraint the non-linear magnet of dizzy process, halved tie particle of swooning focuses on, and makes the low density particle at edge focus on the high-density particles at the center that is added to, avoids the adverse effect of restrainting dizzy particle.

Technical scheme of the present invention is as follows, the non-linear magnet of the dizzy process of a kind of accelerator bundle, comprise four magnetic poles be oppositely arranged between two, be provided with excitation wire bag outside each magnetic pole and pass into exciting current, wherein, be provided with a pair shaded pole in the centre position of four magnetic poles, the cartridge of described shaded pole is plane, and the magnetic field that plane cartridge produces is null field.

Further, the non-linear magnet of the dizzy process of accelerator bundle as above, wherein, the cartridge of four described magnetic poles is hyperboloid or other curved surface.

Further, the non-linear magnet of the dizzy process of accelerator bundle as above, wherein, the magnetic field that the cartridge of four described magnetic poles produces is line focus district or non-linear focused district.

Beneficial effect of the present invention is as follows: the null field, magnetic field that the cartridge of shaded pole of the present invention produces does not have an impact to Particles Moving, focal zone, the magnetic field halved tie that the cartridge of four magnetic poles produces particle of swooning focuses on, thus make the low density particle at edge focus on the high-density particles at the center that is added to, avoid the adverse effect of restrainting dizzy particle.

Accompanying drawing explanation

Fig. 1 is four/a part of structural representation of magnet arrangement entirety in the specific embodiment of the invention;

Fig. 2 is the Distribution of Magnetic Field schematic diagram (being depicted as the half of Distribution of Magnetic Field) in the specific embodiment of the invention in X-axis;

Fig. 3 is the example Distribution of Magnetic Field figure of the dizzy particle of process bundle in the specific embodiment of the invention.

Embodiment

Below in conjunction with drawings and Examples, the present invention is described in detail.

The present invention is the improvement that the basis of the quadrupole magnet adopted at accelerator is carried out, original quadrupole magnet comprises four magnetic poles 1 be oppositely arranged between two, be provided with excitation wire bag 3 outside each magnetic pole and pass into exciting current, as shown in Figure 1, in Fig. 1 be depicted as whole magnet four/part, full figure is about X-coordinate axle and Y-coordinate axial symmetry.The present invention adds a pair shaded pole 2 in the centre position of four magnetic poles, and its cartridge is plane, and the magnetic field making it produce is null field 4.The cartridge face of original quadrupole magnet magnetic pole 1 is hyperboloid, as (x-a) * y=b curve along Z-direction stretch the curved surface that formed, a and b be greater than zero constant; Also other curved surface can be designed to as required, as 3 (x-a) ²* y-y ³=b curve to stretch the curved surface formed along Z-direction, a and b be greater than zero constant.The magnetic field that magnetic pole produces is line focus district 5 (also can be designed to other non-linear focused district as required), 4 pairs, null field Particles Moving does not have an impact, halved tie particle of swooning in line focus district 5 focuses on, thus make the low density particle at edge focus on the high-density particles at the center that is added to, avoid the adverse effect of restrainting dizzy particle.

When carrying out restrainting dizzy process, first beam cross section is needed to make very flat bundle, such as adopt traditional quadrupole magnet by while bundle spot in the Y direction pack, expand in X-direction, make the bundle spot of X-direction very large, and bundle spot is in the Y direction very little, this processing method was the most suitable before line is practiced shooting.Gaussian Profile shape curve in Fig. 3 is the particle density distribution situation of this line in X-axis.Be analogous to the result of Fig. 2, the ABC broken line in Fig. 3 is the Distribution of Magnetic Field in X-axis.Being wherein the bundle core part of line in AB interval, is the dizzy part of bundle outside AB interval.Under this magnetic fields, the particle density in AB interval is constant, and the particle outside AB interval is owing to being subject to line focus power, and the particle of A, B point is motionless, and the focusing force be more subject to away from the particle of A, B point is larger.Through the drift of certain distance, the dizzy particle of bundle will be added in bundle core, thus avoids halved tie and to swoon the collimation cutting of particle.

From the characteristic of quadrupole magnet, line, while X-direction focuses on superposition, often defocuses in the Y direction, but due to line very flat, therefore debunching force is in the Y direction very weak, can ignore.

Obviously, those skilled in the art can carry out various change and modification to the present invention and not depart from the spirit and scope of the present invention.Like this, if belong within the scope of the claims in the present invention and equivalent technology thereof to these amendments of the present invention and modification, then the present invention is also intended to comprise these change and modification.

Claims

1. the non-linear magnet of the dizzy process of accelerator bundle, comprise four magnetic poles (1) be oppositely arranged between two, be provided with excitation wire bag (3) outside each magnetic pole (1) and pass into exciting current, 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).

2. the non-linear magnet of the dizzy process of accelerator 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 accelerator 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.