CN106132065A - 230MeV superconducting cyclotron avoids the field structure of draw-out area harmful resonance - Google Patents

Abstract

The present invention relates to a kind of 230MeV superconducting cyclotron and avoid the field structure of draw-out area harmful resonance, protrude the breach offering rounding off at side profile at magnetic pole, use and coordinate installation with the permeability magnetic material cushion block of material at the magnetic pole protrusion side gap position offered with magnetic pole；The inner surface of described permeability magnetic material cushion block and the protrusion side breach tight fit of magnetic pole；The profile rounding off protruded before and after side breach of end and magnetic pole before and after the outer surface profile of permeability magnetic material cushion block, and form the opisthotonos angle avoided needed for the harmful resonance of draw-out area.The present invention, under conditions of not increasing magnetic pole radius, reduces axial resonance frequency v before leading point_z, it is to avoid before leading point, pass through v_zThe resonance of=1, prevents the axial quality variation of educt beaming flow caused by this resonance, reduces the beam loss of draw-out area, and then reduces the irradiation dose suffered by accelerator attendant.

Description

230MeV superconducting cyclotron avoids the field structure of draw-out area harmful resonance

Technical field

The invention belongs to cyclotron designing technique, be specifically related to a kind of 230MeV superconducting cyclotron and avoid drawing The field structure of district's harmful resonance.

Background technology

Isochronism principle according to cyclotron, has

$B_0\left(r\right)=B_{center}\mathrm{\γ}\left(r\right)=B_{center}\sqrt{\frac{c^2}{c^2-{\left({\mathrm{\ω}}_{0}r\right)}^2}}---\left(1\right)$

In formula, B_centerBeing central magnetic field, c is the light velocity, ω₀For particle cyclotron frequency, r is radius of gyration.To fixed-field with Cyclotron frequency B_center、ω₀, by formula (1) can be given theory etc. time field.According to formula (1), cyclotron isochronism magnetic Field is with increasing radii.

The free oscillation frequency approximate expression of isochronous cyclotron is:

$v_z^2=n+\frac{N^2}{N^2-1}\·F\·(1+2{\tan }^2\mathrm{\ξ})---\left(2\right)$

$v_r^2=1-n+\frac{3\·N^2}{(N^2-1)\·(N^2-4)}\·F\·(1+2{\tan }^2\mathrm{\ξ})---\left(3\right)$

In formula, modulation degree F is determined by following formula:

$F=1-\frac{<B^2>}{<B{>}^2}=\frac{\mathrm{\&alpha;}\&CenterDot;(1-\mathrm{\&alpha;})\&CenterDot;{(B_{hill}-B_{valley})}^2}{{(\mathrm{\&alpha;}\&CenterDot;B_{hill}+(1-\mathrm{\&alpha;})\&CenterDot;B_{valley})}^2}---\left(4\right)$

Wherein,<B>=α B_hill+(1-α)·B_valley (5)

α is the ratio shared by magnetic pole, B_hill、B_valleyIt is respectively the magnetic field in central plane superiors district and paddy district, typically comes Say, B_hill＞ B_valley.<B>it is the average magnetic field at radius r.In order to avoidThe beam loss that resonance causes, for drawing Go out the medium-energy cyclotron of 230MeV proton, number of blade N >=4 of magnetic pole, therefore (3) formula is approximately (6) formula:

$v_r^2=1-n---\left(6\right)$

In formula

Known by (7) formula, when cyclotron average magnetic field is not further added byI.e.Shi Jin Magnetic rigidity maximum, be brought in (6) formula and obtain v_rNear=1, magnetic rigidity is maximum, i.e. v_rThe magnetic rigidity of=1 near-resonance embodies The size of cyclotron maximum acceleration energy, usual isochronous cyclotron selects at v_rDraw after=1 radius, with Just magnetic field pulse guide field is made full use of.At this moment, owing to cyclotron average magnetic field begins to decline with after increasing radii to peak value, draw The region that the magnetic field of point declines with radius already in average magnetic field.From (7) formula, n ＞ 0 near leading point, and along with Average magnetic field decrease speed accelerates, and n becomes rapidly big.From (2) formula, before leading point, likely pass through v_zThe resonance of=1.? V is passed through before leading point_zThe resonance of=1 can cause axial bundle stream quality variation.

In order to reduce axial resonance frequency v before leading point_z, according to (2) formula, need to reduce the field in front zonule, leading point Landing index n；Or reduce modulation degree F in front zonule, leading point；Or reduce front zonule, leading point inner-spiral angle ξ.But Reducing field landing index n to mean to increase magnetic pole radius, can cause extraction system difficult design, extraction voltage is too high；The least In region, modulation degree F change slowly cannot meet the requirement that local diminishes；Reduce front zonule, leading point inner-spiral angle ξ, Magnetic pole can be caused to protrude side profile and occur opisthotonos angle drastically near draw-out area, directly processing is difficult to ensure that and processes draw-out area Required magnetic pole contour line.

Summary of the invention

Present invention aims to problems of the prior art, it is provided that a kind of 230MeV superconducting cyclotron Avoid the field structure of draw-out area harmful resonance, under conditions of not increasing magnetic pole radius (not affecting extraction system design), fall Axial resonance frequency v before low leading point_z, it is to avoid before leading point, pass through v_zThe resonance of=1.

Technical scheme is as follows: a kind of 230MeV superconducting cyclotron avoids the magnetic pole of draw-out area harmful resonance Structure, protrudes the breach offering rounding off at side profile, employing and the magnetic pole permeability magnetic material cushion block with material in institute at magnetic pole The magnetic pole offered protrudes side gap position and coordinates installation；The inner surface of described permeability magnetic material cushion block is tight with the protrusion side breach of magnetic pole Coordinate；The profile rounding off protruded before and after side breach of end and magnetic pole before and after the outer surface profile of permeability magnetic material cushion block, and Form the opisthotonos angle avoided needed for the harmful resonance of draw-out area.

Further, 230MeV superconducting cyclotron as above avoids the field structure of draw-out area harmful resonance, its In, for single magnetic pole, described permeability magnetic material cushion block is an integral single piece, or is divided into sliceable multiple accessories Combination.

Further, 230MeV superconducting cyclotron as above avoids the field structure of draw-out area harmful resonance, its In, described permeability magnetic material cushion block is connected by bolt is fixing with the protrusion side breach of magnetic pole.

Further, 230MeV superconducting cyclotron as above avoids the field structure of draw-out area harmful resonance, its In, for having the cyclotron of multiple magnetic pole, at the protrusion side profile of each magnetic pole, offer the breach of rounding off, The shape and size of the permeability magnetic material cushion block that breach is arranged are identical.

Further, 230MeV superconducting cyclotron as above avoids the field structure of draw-out area harmful resonance, its In, the magnetic field of draw-out area is fine-tuned by processing the appearance contour shape of described permeability magnetic material cushion block.

Beneficial effects of the present invention is as follows: use the solution of the present invention, cyclotron magnetic-field measurement with when having a snack, The magnetic field of local fine regulation draw-out area can be come, it is to avoid to whole magnetic by the outer surface profile of machining permeability magnetic material cushion block The difficulty of pole processing, improves the line resonance in draw-out area.The present invention (does not affect extraction system to set not increasing magnetic pole radius Meter) under conditions of, reduce axial resonance frequency v before leading point_z, it is to avoid before leading point, pass through v_zThe resonance of=1, prevents by this The axial quality variation of educt beaming flow that resonance causes, reduces the beam loss of draw-out area, and then reduces accelerator attendant institute The irradiation dose being subject to.

Accompanying drawing explanation

Fig. 1 is the structural representation of 230MeV superconducting cyclotron；

Fig. 2 is the field structure schematic diagram that 230MeV superconducting cyclotron avoids draw-out area harmful resonance；

Fig. 3 is to use the structure of the present invention to have a snack magnetic field and the result schematic diagram of Particle tracking calculating after magnetic pole.

Detailed description of the invention

With embodiment, the present invention is described in detail below in conjunction with the accompanying drawings.

The structure of 230MeV superconducting cyclotron is as it is shown in figure 1,5 be magnetic pole in figure, and twist, this is this area Known technology.As in figure 2 it is shown, the mode that the present invention uses magnetic pole to have a snack solves the problem that line resonates in draw-out area, provided 230MeV superconducting cyclotron avoid the field structure of draw-out area harmful resonance as follows: protrude at magnetic pole 1 and open at side profile If rounding off and the breach 3 being easily worked, use the permeability magnetic material cushion block 2 of material as magnetic pole 1 that magnetic pole is had a snack, By bolt 4, permeability magnetic material cushion block 2 is coordinated installation with the protrusion side breach 4 of magnetic pole 1.The inner surface of permeability magnetic material cushion block 2 with The protrusion side breach 3 of magnetic pole 1 closely cooperates；Before and after the outer surface profile of permeability magnetic material cushion block 2, end lacks with the protrusion side of magnetic pole 1 Profile rounding off before and after mouth 3, and form the opisthotonos angle avoided needed for the harmful resonance of draw-out area.Permeability magnetic material cushion block 2 is permissible It is designed as meeting the arbitrary shape of above-mentioned requirements, local fine can be carried out by the outer surface profile of machining permeability magnetic material cushion block The magnetic field of regulation draw-out area.

For single magnetic pole 1, permeability magnetic material cushion block 2 can be integral single piece；Sliceable multiple join can also be divided into The combination of part, the splicing of multiple accessories coordinates the protrusion side breach 4 being arranged on magnetic pole 1, and the cushion block entirety after combination should meet above-mentioned Closely cooperate and the structural requirement of rounding off with the side breach that protrudes of magnetic pole.

Generally, for having the cyclotron of multiple magnetic pole, offer at the protrusion side profile of each magnetic pole Rounding off and the breach being easily worked, the shape and size of the permeability magnetic material cushion block 2 of all magnetic poles should be consistent.

Embodiment

In certain as a example by energy superconducting cyclotron.This accelerator has four magnetic pole blades, magnetic pole radius R=860mm.Root According to magnetic field calculation, in order to avoid passing through v before leading point_zThe resonance of=1, starts opisthotonos angle occur from magnetic pole radius r=810mm. From the beginning of magnetic pole radius r=770mm, magnetic pole protrudes the profile design machining gap of side, increases permeability magnetic material cushion block.Magnetic pole lacks At Kou, profile and the inner surface profile of permeability magnetic material cushion block that coordinates with it are circular arc, and arc radius R is 70mm, more than processing Tool radius (42mm) needed for magnetic pole, it is simple to processing；The opisthotonos angle θ of the outer surface profile of permeability magnetic material cushion block is 110 degree, warp Cross magnetic field and Particle tracking to calculate, Fig. 3 result of calculation show, use such magnetic pole indentation, there profile and coordinate with it Permeability magnetic material cushion block size, before going out draw-out area, can make v_z＜ 1, it is to avoid v_zThe harmful resonance of=1.

Obviously, those skilled in the art can carry out various change and the modification essence without deviating from the present invention to the present invention God and scope.So, if these amendments and modification to the present invention belong to the model of the claims in the present invention and equivalent technology thereof Within enclosing, then the present invention is also intended to comprise these change and modification.

Claims (5)

1. a 230MeV superconducting cyclotron avoids the field structure of draw-out area harmful resonance, it is characterised in that: at magnetic pole Protrude the breach (3) offering rounding off at side profile, employing and the magnetic pole permeability magnetic material cushion block (2) with material offered Magnetic pole protrudes breach (3) position, side and coordinates installation；The inner surface of described permeability magnetic material cushion block (2) and the protrusion side breach of magnetic pole (3) tight fit；Profile before and after end and protrusion side breach (3) of magnetic pole before and after the outer surface profile of permeability magnetic material cushion block (2) Rounding off, and form the opisthotonos angle avoided needed for the harmful resonance of draw-out area.

2. 230MeV superconducting cyclotron as claimed in claim 1 avoids the field structure of draw-out area harmful resonance, and it is special Levy and be: for single magnetic pole, described permeability magnetic material cushion block (2) is an integral single piece, or is divided into sliceable The combination of multiple accessories.

3. 230MeV superconducting cyclotron as claimed in claim 1 or 2 avoids the field structure of draw-out area harmful resonance, its It is characterised by: described permeability magnetic material cushion block (2) is connected by bolt (4) is fixing with protrusion side breach (3) of magnetic pole.

4. 230MeV superconducting cyclotron as claimed in claim 1 or 2 avoids the field structure of draw-out area harmful resonance, its It is characterised by: for having the cyclotron of multiple magnetic pole, at the protrusion side profile of each magnetic pole, offer rounding off Breach, the shape and size of permeability magnetic material cushion block that breach is arranged are identical.

5. 230MeV superconducting cyclotron as claimed in claim 1 or 2 avoids the field structure of draw-out area harmful resonance, its It is characterized by the appearance contour shape processing described permeability magnetic material cushion block so that the magnetic field of draw-out area is fine-tuned.