CN207201060U

CN207201060U - Cyclotron and the magnetic pole for cyclotron

Info

Publication number: CN207201060U
Application number: CN201720510663.7U
Authority: CN
Inventors: W·克里文; S·扎雷姆巴
Original assignee: Ion Beam Applications SA
Current assignee: Ion Beam Applications SA
Priority date: 2016-05-13
Filing date: 2017-05-09
Publication date: 2018-04-06
Anticipated expiration: 2027-05-09
Also published as: JP6446089B2; CA2965016A1; EP3244709B1; CA2965016C; CN107371316B; CN107371316A; EP3244709A1; JP2017204469A

Abstract

It the utility model is related to cyclotron and the magnetic pole for cyclotron.A kind of magnetic pole for isochronism sector-focused cyclotron includes including the upper surface using following four edges edge as border around the alternatively distributed mound fan blocks of central axis Z and paddy fan block, each mound fan block：Upper peripheral edge, upper center edge, the first and second upper edges and the peripheral surface that lower object-line is extended to from the upper peripheral edge.The upper peripheral edge of at least one mound fan block further comprises the concave portions that depression is limited relative to the central axis, and the depression is fanned at least partially in corresponding mound to be extended on the peripheral edge of block.

Description

Cyclotron and the magnetic pole for cyclotron

Technical field

It the utility model is related to cyclotron.Specifically, the convolution of isochronism sector focusing is the utility model is related to accelerate Device, the enhancing that the cyclotron has the excitation charged particle beam to extraction focus on.

Background technology

Cyclotron is a kind of round particle accelerator, wherein negatively charged particle or positively charged particle along spiral path from The center of cyclotron outwards accelerates until some MeV energy.Except as otherwise noted, term " cyclotron " is following It is used to refer to isochronous cyclotron in content.Cyclotron is used for various fields, such as nuclear physics, medical therapy, Such as proton therapy, or for radiopharmacy.Specifically, cyclotron can be used for production be suitable for PET imaging (just Electron emission x-ray tomography art) short life Positron emitting isotopes or production for example for SPECT be imaged (monochromatic light Son transmitting computerized tomography) gamma emission isotope (for example, Tc99m).

Cyclotron includes some elements, including injected system, the radio frequency (RF) for accelerating charged particle accelerate System, for along exact path guide the magnetic system of accelerated particle, the extraction system for collecting the particle so accelerated and For the vacuum system of vacuum to be created and maintained in cyclotron.

By injected system with relatively low initial velocity by the particle beams that charged ion forms at cyclotron center At or near be introduced into gap.As show in Figure 3, the particle beams is accelerated in order and repeatedly by RF acceleration systems And guided outwardly along the spiral path in the gap by magnetic field caused by magnetic system.When the particle beams reaches its target energy During amount, the particle beams is drawn from cyclotron by the extraction system provided in leading point PE.The extraction system can be with Including the stripper being for example made up of thin graphite flake.For example, the H through stripper^-Ion loses two electronics and is changed into just 's.Therefore, its symbol of the curature variation in their path in magnetic field, and therefore draw particle from cyclotron towards target Beam.Other well-known extraction systems of those skilled in the art be present.

Magnetic system produces magnetic field, and the magnetic field guides charged particle beam along spiral path and makes its focusing, until itself plus Speed arrives its target energy.In herein below, term " particle ", " charged particle " and " ion " synonymously makes indistinction With.Magnetic field is produced in the gap limited by two magnet coils 14 being wrapped on two magnetic poles between these poles.Convolution The magnetic pole of accelerator is often divided into alternate mound fan block and paddy fan block around central axis distribution.Gap between two magnetic poles It is smaller and larger at paddy fan block at the fan block of mound.Therefore create high-intensity magnetic field in the mound gap portion in the fan block of mound and fanned in paddy Weaker magnetic field is created in paddy gap portion in block.This kind of azimuthal magnetic field change reaches mound gap portion every time in the particle beams When make the particle beams radially and vertical focus on.For this reason, this kind of cyclotron is sometimes referred to as sector focusing convolution and accelerated Device.In certain embodiments, fan block in mound has fans block geometry with circular as a cake, has towards central axis base The first and second side surfaces for being radially extended in sheet, the peripheral surface generally bent, the center surface adjacent with central axis, With the upper surface of the side of restriction mound gap portion.Determined by the first and second lateral edges, peripheral edge and center edge upper surface Boundary.

In fact, the particle beams has sectional area.The target of cyclotron is to produce multi-focus as far as possible (that is, to have small Area of section) the charged particle beam with given energy.The change in the magnetic field that the fan block of mound in succession and paddy fan block are created Beam is focused on lens light beam can be made to focus on similar mode.However, limited between the particle beams is drawn into two magnetic poles Gap when, the particle beams loses the borderline region of its uniformity through magnetic field, and this focusing to the particle beams is unfavorable.This is a spy Other sensitive issue, because the one side particle beams has its ceiling capacity in leading point, and on the other hand, in magnetic pole, magnetic Control magnetic field more difficult at the peripheral edge of field rapid decrease.In order to strengthen the focusing of the particle beams of extraction, the art Have been proposed being formed to the protrusion of the peripheral edge to change the periphery sides that block is fanned on mound by added gradient corrector The geometry of edge.Gradient corrector is relatively small bloom for the size of mound fan block, and the bloom is attached to mound Fan the peripheral edge of block.This kind of gradient corrector allows to change the magnetic field near peripheral edge and therefore local modification mound fan block Peripheral edge near magnetic field to improve the focusing of outgoing particle beam.If however, the use of protruding-type gradient corrector has Dry shortcoming.First, accommodating the volume of the vacuum chamber of magnetic pole must correspondingly increase, it is therefore desirable to more energy and time come from Vacuum chamber pumps gas.Second, the overall weight increase of cyclotron, because the weight of one side gradient corrector in itself, And the size of population of the increase of the outer wall of another aspect vacuum chamber, and flux therefore returns the size of yoke；Both facilitate back Rotation accelerator weight significantly increases.3rd, the position of protruding-type gradient corrector is vital；Small position deviation can Big changes of magnetic field can be produced.Gradient corrector must be accurately fixed on the outer of all mound fan blocks manually by those skilled in the art Enclose at the same position on surface.Certainly, this is a key and expensive operation.4th, protruding-type gradient corrector have make The effect that magnetic field is outwards offset, it pulls out particle towards the peripheral edge of the mound gap portion between a pair of relative mound fan blocks The path of beam, in the peripheral edge, magnetic field loses its uniformity.This displacement, which also results in, loses useful magnetic field and therefore Need to increase coil current to compensate this loss.Therefore, control the characteristic of the particle beams of extraction more difficult and expensive.

Therefore, this area still need it is a kind of allow to draw in a manner of efficient and be cost-efficient more focus on and more The isochronism sector-focused cyclotron of the predictable particle beams.

Utility model content

The utility model is defined with appended independent claims.Preferable implementation is defined in the dependent claims Example.

A kind of magnetic pole for cyclotron is the utility model is related to, the magnetic pole includes at least three mound fan block and phase The paddy including basal surface with number fans block, and the mound fan block and paddy fan block are alternately distributed around central axis Z, each mound fan Block includes：

(a) upper surface limited by the following：

● upper peripheral edge, the upper peripheral edge, for border, and are defined as described with distal end on first and second Upper surface, edge that position is farthest from the central axis；

● upper center edge, the upper center edge as border and are defined as on described using near-end on first and second Surface, edge that position is nearest from the central axis；

● distal end on described first is connected by the first upper edge, first upper edge with near-end on first；

● distal end on described second is connected by the second upper edge, second upper edge with near-end on second；

(b) the first and second side surface, each side surface extend transversely to position from first and second upper edge In the basal surface of the corresponding paddy fan block of the either side of mound fan block, so as to by the first and second lower edges be defined to make side surface and The intersecting edge of adjacent bottom surface, under first and second lower edge each has position farthest from the central axis Distally；

(c) peripheral surface, the peripheral surface extend to lower object-line, the lower object-line quilt from the upper peripheral edge It is defined to the section using the lower distal end of first and second lower edge as border；

Characterized in that, the upper peripheral edge of at least one mound fan block includes limiting depression relative to the central axis Concave portions, described be recessed extend at least partially in a part for the peripheral surface of corresponding mound fan block.

Preferably, the depression is generally wedge shape, wherein first and second assemble line (preferably straight line) to assemble Angle θ extends outwardly away from the upper peripheral edge, the convergent angle is preferably incorporated between 70 ° and 130 °, more preferably 80 ° with Between 110 °, be most preferably 90 ° ± 5 °.

The depression has a convergence portion away from the upper peripheral edge, the convergence portion have following geometry it One：

● form the anxious turning of triangular shaped recess；

● form the straight edge of trapezoidal recess；Or

● form the rounded edges of arcuate recess.

Preferably, the upper peripheral edge has azimuth length Ah, and wherein, the concave portions are outer described Between the 3% and 30% of the azimuth length of peripheral edge, preferably between 5% and 20%, more preferably 8% with Extend between 15%.

Preferably, the depression separates with first and second upper edge.Alternately, it is described depression with it is described First upper edge is adjacent.

The depression can extend in a part for the peripheral surface.

Preferably, the depression extended the relative with a part of ζ of the height of the peripheral surface of the peripheral surface The part answered, the height are parallel to the central axis and measured on described between peripheral edge and the lower object-line , wherein, the part ζ is included between 25% and 75%, preferably between 40% and 60%, most preferably 45% with Between 55%.

For the smooth change with magnetic field, the peripheral surface forms the scarf adjacent with the upper peripheral edge.

Preferably, the upper peripheral edge is circular arc, the center of the circular arc offset relative to the central axis and Radius be no more than from the central axis to the midpoint of the upper peripheral edge distance 85%, the midpoint to described first It is equal with the distance of distal end on second.

The number N of mound fan block is preferably 3,4,5,6,7 or 8, more preferably N=4.

The utility model further relates to a kind of convolution for being used to make particle accelerate (beamacceleration) on the given path being included in gap Accelerator, the cyclotron include the first and second magnetic pole as described above, wherein, first and second magnetic pole is determined Position formed into symmetrical on the mesion perpendicular with the central axis of the first and second magnetic poles, between the magnetic pole it is described between Gap, wherein forming mound gap portion between two opposite mound fan blocks and forming paddy clearance portion between two opposite paddy fan blocks Point.

Preferably, the depression of the cyclotron has the first and second depression far points, first and second depression Far point distance L10 separated from each other, and wherein, the mound gap portion between a pair of mounds fan block of first and second magnetic pole With average height Gh, and wherein, the ratio Gh/L10 is included between 5% and 100%, preferably 10% with Between 50%, more preferably between 20% and 33%.

The cyclotron can also include two opposite upper tables positioned at the mound of first and second magnetic pole fan block The leading point in the gap portion of mound between face, the given path of the particle beams are spiral paths outwardly, it is described outwardly Spiral path around the central axis circulate until can along draw path be driven out from the cyclotron with to Untill first leading point for the particle beams surely measured, and wherein, the depression is located at the leading point downstream, its Middle and lower reaches are limited relative to particle beams direction so that it is described extraction path to be included between 80 ° and 100 °, preferably Intersect with the depression line at angle of the ground between 85 ° and 95 °.

Preferably, the cyclotron further comprises that second in the mound fan block for limiting the second extraction path draws Go out a little, and including positioned at second leading point downstream second depression so that it is described second draw path with including Intersect with the described second depression line at angle between 80 ° and 100 °, preferably between 85 ° and 95 °.

Preferably, the cyclotron includes two opposite upper tables positioned at the mound of first and second magnetic pole fan block The leading point in the gap portion of mound between face, wherein：The given path of the particle beams is spiral path outwardly, described Spiral path is circulated around the central axis and provided until that can be driven along extraction path from the cyclotron outwardly Untill the first leading point for having the particle beams of given energy, the depression is located at the leading point downstream, and its middle and lower reaches is Limited relative to the particle beams direction so that the extraction path is by be included between 80 ° and 100 °, preferably exist Intersect with the depression to leave corresponding mound gap portion at angle between 85 ° and 95 °.

Preferably, the cyclotron is also including the second extraction in the mound fan block for limiting the second extraction path Point, and including the second depression positioned at second leading point downstream, so that the second extraction path is by wrap Angle between 80 ° and 100 °, preferably between 85 ° and 95 ° is included with the described second depression to intersect to leave between corresponding mound Gap part.

Preferably, the first leading point and the second leading point are located in same mound gap portion.

Brief description of the drawings

Of the present utility model these will be explained in more detail with further aspect by way of example and refer to the attached drawing, In the accompanying drawings：

Fig. 1 (a) and Fig. 1 (b) schematically show the side elevational cross-section according to cyclotron of the present utility model Figure and top view；

Fig. 2 shows the example that block and paddy fan block are fanned according to the mound of cyclotron of the present utility model；

Fig. 3 show half cyclotron and charged particle acceleration path fragmentary, perspective view (in order to strengthen observability, Flux is not shown and goes back in yoke the outlet for drawing particle)；

Fig. 4 (a) and Fig. 4 (b) shows the example that block is fanned according to mound of the present utility model, and the mound fan block includes gradient school Positive device；

Fig. 5 (a) and Fig. 5 (b) respectively illustrates the reality of the magnetic field line with gradient corrector and without gradient corrector Example；

Fig. 6 (a) and Fig. 6 (b) shows the geometry of the concave portions for the upper object-line that block is fanned according to mound of the present utility model The example of shape；

Fig. 7 (a) to Fig. 7 (d) shows the example of the geometry according to depression of the present utility model；

Fig. 8 shows the example for the magnetic pole for having two depressions and two leading points according to the utility model

Fig. 9 shows another example that block is fanned according to mound of the present utility model, and the mound fan block includes the warp of mound fan block Improved upper peripheral edge design；

Figure 10 (a) shows the 3rd example according to mound fan block of the present utility model and with depression；

Figure 10 (b) shows the example of pole insert.

Embodiment

According to the geometry of cyclotron of the present utility model

Isochronism sector-focused cyclotron is the utility model is related to, hereinafter referred in above technical background part The cyclotron of the type of discussion.As shown in Figure 3, charged particle is made along spiral according to cyclotron of the present utility model Path 12 outwards accelerates until they are brought out with some MeV energy from the central area of cyclotron.For example, so draw Charged particle can be proton H⁺Or deuteron D⁺.Preferably, the energy that the particle of extraction reaches is included in 5MeV and 30MeV Between, more preferably between 15MeV and 21MeV, be most preferably 18MeV.Cyclotron with this kind of energy is for example It is suitable for being imaged the same position of short life positron emission used in (Positron Emission Tomography) in PET for producing Element is suitable for the gamma emission isotope (example that production is used for SPECT imagings (single photon emission computed tomography) Such as, Tc99m).

As shown in Fig. 1 (a), two substrates 5 are included according to cyclotron 1 of the present utility model and form yoke together Flux return yoke 6.Flux returns yoke and forms the outer wall of cyclotron and by the way that the magnetic field control outside coil 14 is held It is contained in cyclotron.The cyclotron further comprises the first and second magnetic poles 2 being located in vacuum chamber, the magnetic Pole is on the mesion MP perpendicular to central axis Z symmetrically face each other and the certain interval 7 that is separated from each other.The yoke and magnetic Pole is all made up of magnetic material, preferably mild steel and forms a part for magnetic system.Magnetic system is by will be by conduction Thread first and second coil 14 be wrapped on the first and second magnetic poles and coordinate the magnetic pole and flux return yoke it Between complete in the annular space that limits.

As shown in Fig. 1 (b) and Fig. 2, each of first and second magnetic poles 2 include radially dividing around central axis Z At least N=3 mound fan block 3 of cloth (Fig. 1 (b) illustrates N=4 preferred embodiment).Light shadow region is expressed as in Fig. 1 (b) Each mound fan block 3 there is the upper surface 3U that extends in the range of the azimuth angle alpha h of mound.Each of first and second magnetic poles 2 enter The radially-arranged paddy of central axis Z that surrounds that one step includes same number N fans block 4, and dark shadow region is expressed as in Fig. 1 (b). Each paddy fan block 4 both sides are that blocks 3 are fanned and with the basal surface 4B extended in the range of paddy azimuth angle alpha v in two mounds, so that Obtain α h+ α v=360 °/N.

The mound fan block 3 and paddy fan block 4 of first magnetic pole 2 fan block 3 respectively for the relative mound of the second magnetic pole 2 and paddy fans block 4. Path 12 along the particle beams shown in Fig. 3 is included in the gap 7 for separating the first magnetic pole with the second magnetic pole.First magnetic pole The mound gap portion 7h limited between upper surface 3U of the gap 7 therefore including two relative mound fan blocks 3 between the second magnetic pole The paddy gap portion 7v limited with two between the basal surface 4B of relative paddy fan block 4.Mound gap portion 7h has mean gap height Gh is spent, is defined as average height of the mound gap portion on two opposing upper 3U region.

Average mound and paddy clearance height are accordingly measured as mound fan block and fanned with paddy on the whole upper surface and lower surface of block Clearance height average value.The average value of paddy clearance height have ignored any opening on basal surface.

Upper surface 3U is limited (referring to Fig. 2) by the following：

● upper peripheral edge 3up, the upper peripheral edge are defined using distal end 3ude on first and second as border For upper surface, edge that position is farthest from central axis Z；

● upper center edge 3uc, the upper center edge as border and are defined using near-end 3upe on first and second For the upper surface, edge that position is nearest from the central axis；

● the first upper edge 3ul, first upper edge by described first distal end and near-end phase on described first Connection；

● the second upper edge 3ul, second upper edge by described second distal end and near-end phase on described second Connection；

Mound fan block 3 further comprises (referring to Fig. 2)：

● the first and second side surface 3L, each side surface extend transversely to be located at mound from the first and second upper edges Fan the basal surface of the corresponding paddy fan block of the either side of block, so as to by the first and second lower edge 3ll be defined to make side surface and The intersecting edge of adjacent bottom surface, first and second lower edge each have the position lower distal end farthest from central axis 3lde；

● peripheral surface 3P, the peripheral surface extend to lower peripheral edge 3lp, the lower periphery sides from upper peripheral edge Edge is defined as the section using the lower distal end 3lde of the first and second lower edges as border.

The average height Hh of mound fan block is to be averaged between lower edge and upper edge parallel to what central axis measured Distance.

The end at edge be defined as limiting the end for limiting the edge two is one of extremely.Near-end is edge , the end that position is nearest from central axis Z.Distal end is edge, the position end farthest from central axis Z.End can be with It is the turning point for being defined as the point that two or more lines meet.Turning point can also be defined as curve near tangent and change symbol Number or show the point of discontinuity.

Edge is the line segment that two surfaces are met.Edge limits two as defined above using both ends as border The one side on each surface in the surface met.Due to the limitation reason of machinery tools and in order to reduce stress concentration, Two surfaces are often met with given radius of curvature R, and this makes it difficult to the accurate geometry for limiting edge and intersecting with two surfaces Position.In this case, edge is defined as two outer pushing surface phases with being extrapolated for intersecting each other with unlimited curvature (1/R) The geometrical line of friendship.Top edge is the edge intersected with the upper surface 3U of mound fan block, and lower edge is the basal surface with paddy fan block Edge intersecting 4B.

Peripheral edge is defined as the edge for including the position point farthest from central axis Z on surface.If solstics is The shared turning point in two edges, then peripheral edge or the maximum edge of surface, distance center axis Z average distance. For example, upper peripheral edge is the edge for including the position point farthest from central axis of upper surface.If mound fan block is compared to one Fruits cake, peripheral edge by be Fruit cake peripheral crust.

In a similar way, center edge is defined as the edge for including the position point nearest from central axis Z on surface. For example, upper center edge is the edge for including the position point nearest from central axis Z of upper surface.

Lateral edges are defined as the center edge of proximal end being linked to the edge of the peripheral edge of far-end.Lateral edges Therefore near-end is the end intersected with center edge of the lateral edges, and the distal end of the lateral edges is the lateral edges The end intersected with peripheral edge.

Depending on the design of cyclotron, upper center edge/lower center edge can have different geometries.Most Common geometry is the often circular concave (or sag vertical curve) for having finite length (≠ 0) relative to central axis, The concave using be separated from each other first and second on near-end/lower near-end as border.This configuration introduces grain in clear space It is useful during the gap of beamlet and other elements.Under the first alternative configuration, the first and second center near-ends are merged into list Individual center near point, so as to form upper surface 3U summit, the summit only includes three edges, and center edge has zero-length. If mound fan block is compared into a Fruit cake again, the tip of this part is by the center edge phase with being so reduced to a single point It is corresponding.Under the second alternative configuration, the transitional face from first side edge to second side edge can be curved for central axis Z Bent convex surface, so as to be produced without seamlessly transitting for any turning point.Under this configuration, center edge also reduces into a single point, The a single point is defined as the point of tangent line reindexing.Generally, or even under the first and second alternative configurations, mound fan block does not have Central axis is extended to, concedes and directly surrounds the central area of central axis to allow to insert the particle beams or install other Element.

As shown in Figure 2, the first and second side surface 3L are preferably what is chamfer, so as to respectively in the first and second upsides Edge forms scarf 3ec.Scarf is defined as by cutting away the side formed via two surfaces in the absence of scarf Edge and obtain the intermediate surface between two surfaces.Scarf reduces the angle that edge between two surfaces is formed.Tiltedly Section is often used in mechanical devices for reducing stress concentration.However, in cyclotron, in the upper table of mound fan block The horizontal beveling side surface in face strengthens the focusing of the particle beams when the particle beams reaches mound gap portion 7h.Fan the peripheral table of block in mound Face 3P can also form scarf at upper peripheral edge, and with an improved the magnetic field's regularity near peripheral edge.

N=3 to 8 mound fan block 3 is preferably included according to cyclotron of the present utility model.It is highly preferred that such as scheming It is middle shown, N=4.For N even number value, mound fan block 3 and paddy fan block 4 have to be around central axis according to any right of 2n The distribution of title property, wherein n=1 to N/2.Preferably, n=N/2 so that all N number of mound fan blocks are identical from one another, and all N Individual paddy fan block is identical from one another.For N odd number value, mound fan block 3 and paddy fan block 4 have to be around central axis appointing according to N Meaning symmetry distribution.In a preferred embodiment, for all N=3-8 (i.e. according to N symmetry), during N number of mound fan block 3 surrounds Mandrel line is uniformly distributed.First and second magnetic poles 2 be oriented to their corresponding upper surface 3U face each others and on it is same The mesion MP that the respective central axes Z of first and second magnetic poles 2 of axle is vertical is symmetrical.

The shape of mound fan block is equally frequent (often as previously discussed, without tip) with a Fruit cake Be it is wedge-shaped, wherein the first and second side surface 3L from peripheral surface towards central axis Z assemble (usually not get at it is described in Mandrel line).Mound azimuth angle alpha h with side surface it is (extrapolation) upper edge, at central axis Z or adjacent thereto intersect The convergent angle that the level of point measures is corresponding.Mound azimuth angle alpha h is preferably incorporated between 360 °/2N ± 10 °, more preferably existed Between 360 °/2N ± 5 °, most preferably between 360 °/2N ± 2 °.

Between the paddy azimuth angle alpha v that central axis Z level measures is preferably incorporated in 360 °/2N ± 10 °, more preferably Ground is between 360 °/2N ± 5 °, most preferably between 360 °/2N ± 2 °.Paddy azimuth angle alpha v can be equal to mound azimuth angle alpha h. In the case of symmetry N, α v=360 °/N- α h, for example, for N=4, α v are α h complementary angles, wherein α v=90 °-α h.

Ultimate range Lh between central axis and peripheral edge is preferably incorporated between 200mm and 2000mm, more excellent Selection of land is between 400mm and 1000mm, most preferably between 500mm and 800mm.Proton convolution for 18MeV accelerates Device, ultimate range Lh are typically smaller than 750mm, and can be about 500mm to 750mm, typically 520mm to 550mm. Upper peripheral edge has the azimuth Ah measured on first and second between outer peripheral end, and can be close to Ah=Lh × α h [rad]。

Magnetic is produced in the gap 7 that two magnetic poles 2 and the magnet coil 14 being wrapped on each magnetic pole are formed between magnetic pole (electricity) magnet of field, central area that the magnetic field is shown along Fig. 3, originating in cyclotron (surrounds central axis Z spiral path 12) guides and focuses on the charged particle beam (=particle beams), until it reaches such as 18MeV target energy, So as to draw the charged particle beam.As previously discussed, magnetic pole is often divided into around the alternate mound of central axis Z distributions Fan block and paddy fan block.Therefore high-intensity magnetic field is created in the mound gap portion 7h with average height Gh in the fan block of mound, and in paddy There is average height Gv in fan block>Weaker magnetic field is created in Gh paddy gap portion 7v, so as to create the vertical of the particle beams Focus on.

When the particle beams is introduced into cyclotron, in the referred to as high-field electrode of d fonts electrode (not shown) and attachment The electric field created makes the particle accelerate (beamacceleration) on to the lateral edges of magnetic pole, between the ground voltage electrode that is positioned in paddy fan block, In the paddy fan block, magnetic field is weaker.When each accelerated particle penetrates mound gap portion 7h, the accelerated particle is than it previous There is higher speed in the fan block of mound.Highfield present in the fan block of mound deviate the track of accelerated particle with along with half The bigger substantially circular path of radius along in block is fanned on previous mound than it in footpath.Once the particle beams has accelerated to its target Energy, then the electron beam is drawn from cyclotron in the point for being referred to as leading point PE, as shown in Figure 3.For example, it can lead to H will be accelerated by crossing^-Ion beam is driven through the stripper that is made up of thin foil graphite flake to draw energy protons H⁺.By stripper H^-Ion loses two electronics and is changed into positive H⁺.By changing particle charging symbol, the curature variation symbol in its path in magnetic field Number, and therefore draw particle beams (not shown) from cyclotron towards target.Other known extractions of those skilled in the art The type and details of system and used extraction system are not essential for the utility model.Generally, draw Go out and be a little located in the gap portion 7h of mound.Cyclotron can include some leading points in same mound part.Because convolution adds The symmetry requirement of fast device, there is more than one mound fan block to include leading point.For N symmetry, all N number of mound fan blocks include phase With the leading point of number.Leading point can individually (only one) or simultaneously (once several) use.

Gradient corrector

Fig. 4 (a) and Fig. 4 (b) shows the convolution for including the paddy fan block of N=4 mound fan block and N=4 including basal surface The example of the preferred embodiment of the magnetic pole of accelerator, the mound fan block and paddy fan block are around central axis Z according to the symmetrical of N=4 Sexual intercourse is alternately distributed.Fanning block according to this kind of mound of cyclotron of the present utility model includes the first and second side as defined above Surface 3L, peripheral surface 3P and upper surface 3U.The upper peripheral edge 3up of the upper surface of at least one mound fan block include with it is relative In the adjacent male portion of the concave portions of central axis, the one of the peripheral surface of block so as to characterizing portion is fanned on corresponding mound The depression extended on part.Preferably, the upper peripheral edge 3up of the upper surface of at least one mound fan block includes passing through concave portions 2 male portions separated.

Because the 2n of the even number value to N discussed before symmetry requirement and the symmetry to the N of N odd number value are wanted Ask, identical symmetry must be adapted on the upper peripheral edge of these different mound fan blocks presence or absence of relative to central shaft The situation of the concave portions of line.Therefore, the upper peripheral edge of each mound fan block preferably includes the spill relative to central axis Part 3upc, the depression extended so as to characterizing portion on the peripheral surface of corresponding mound fan block between two male portions 10。

Term " spill " refers to interior bending or caved inward.Concave portions relative to the central axis at edge are edges Towards central axis bending part.The term is with referring to term " convex " phase for bending away or extending outwardly from central axis Instead.

The position of depression can separate with the first and second lateral edges, or adjacent with first or second side edge.It is excellent Selection of land, mound fan block include at least one depression separated with lateral edges.

In prior art cyclotron, protruding-type gradient corrector is used.Protruding-type gradient corrector has some Shortcoming：

● the volume of vacuum chamber is increased,

● increase yoke and whole cyclotron volume,

● the weight of cyclotron is added,

● the gradient corrector that must be manually completed is accurately positioned difficulty,

● magnetic field is outwards offset.

Replace protruding-type gradient corrector that there are some advantages using depressed gradient corrector.First, it allows to reduce The size of the vacuum chamber of magnetic pole is accommodated, is discharged so as to cause to reduce from the energy needed for vacuum chamber discharge gas and reduce gas Time.Second, because on the one hand the weight of mound fan block slightly mitigates rather than increased and on the other hand flux returns the interior of yoke The overall diameter on surface reduces, so the gross weight of cyclotron reduces.3rd, can accurately it be manufactured by numerical control machining With the position of locating recesses, so as to allow optimize the particle beams through mound fan block peripheral edge angulation.4th, work as protrusion Formula gradient corrector make magnetic field outwardly away from when, magnetic field is caved inward by depressed gradient corrector, so as to cause particle The finally circulation in path is inwardly displaced, further away from the peripheral edge of mound fan block, now compared with close to peripheral edge, magnetic field Evenly.Fig. 5 (a) and Fig. 5 (b) is respectively illustrated by depressed gradient corrector (Fig. 5 (a)) and without any gradient calibration The example of the magnetic field line of device (Fig. 5 (b)) skew.Therefore, the characteristic of the particle beams is drawn in control and particularly its focusing is more held It is easy and more predictable.This deviation towards acceleration region also allows to reduce the power for being fed to coil.

Preferably, upper peripheral edge 3up includes the first and second depression far point 10rdp, it is described limited from depression far point it is recessed Sunken border and it is defined as the tangent line reindexing of peripheral edge or shows the point of discontinuity.First and second is recessed Sunken far point is separated from each other distance L10.The depression also includes depression near point 10rpp, the depression near point be defined as position from Depression points nearest central axis Z.First and second depression far point 10rdp pass through the first and second depression convergent boundary 10rc Link depression near point 10rpp.

Cup depth H10 be defined as by first and second depression far point 10rdp be recessed near point 10rpp formed, simultaneously And the height of the triangle by depression near point 10rpp.Cup depth H10 is included in the azimuth length Ah of peripheral edge 3% and 30% between, preferably between 5% and 20%, more preferably between 8% and 15%.Preferably, cup depth H10 and central axis and mound fan block peripheral edge between ultimate range Lh ratio H10/Lh be included in 2% and 20% it Between, preferably between 4% and 15%, more preferably between 6% and 10%.

Upper peripheral edge 3up has the azimuth length Ah measured on first and second between the 3ude of distal end.By first The first depression convergent boundary 10r1 that depression far point is linked to depression near point has length L101 and connects the second depression far point Second depression convergent boundary 10r2 of knot to depression near point has length L102.The length of first and second depression convergent boundaries L101 and L102 is included between the 5% and 30% of the azimuth length Ah of peripheral edge.Preferably, length L101 is equal to length Spend L102 ± 40% (L101=L102 ± 40%).

Preferably, azimuth length Ah of the distance between first and second depression far points L10 scopes in upper peripheral edge 5% and 50% between, preferably between 10% and 30%, most preferably between 15% and 20%.

Preferably, from upper peripheral edge 3up, object-line 3lp prolongs the depression down also in a peripheral surface 3P part Stretch.Therefore the depression extended a part of ζ of peripheral surface height on peripheral surface, the part is parallel to central axis Measured between upper peripheral edge and lower peripheral edge.The part ζ is preferably incorporated between 25% and 100%, preferably Ground is between 40% and 75%, most preferably between 45% and 55%.

As Fig. 6 (a) and Fig. 6 (b) are shown, the concave portions of upper peripheral edge can have in first and second depression Any one of following geometry opened between far point：(a) rectangle, (b) it is trapezoidal, (c) have straight edge or (inwardly or Outwardly) triangle of curved edge, (d) circular arc, (e) two circular arcs, (f) parabola, (g) square, (h) parallelogram, (i) polygon, (j) smoothed curve.Substantially, it is possible to implement any geometry determined by numerical analysis.For example, In the case of trapezoidal, small basis can include depression near point 10rpp, and big basis can be by the first and second depression far points 10rdp is limited.Alternatively, small basis can be limited by the first and second depression far point 10rdp, and big basis can With including the near point 10rpp that is recessed.Triangle can be unequal-sided, isosceles or equilateral.It can also be right angle, wherein Right angle is formed at depression near point 10rpp.Two (or more) in the case of circular arc, they can be inwardly ((e) to the right) Or outwards ((e) to the left).Concave portions be preferably designed such that one bar edge with 80 ° -100 °, preferably 85 ° -95 °, Intersect with the extraction path of the particle beams at substantially 90 ° of angle.

Preferably, depression 10 extends parallel to central axis in a part for peripheral surface.Alternately, it can be from Upper surface with central axis Z downwardly to extend.Distance L10 and/or height H10 can peripherally edge Height increases or reduced independently of one another or simultaneously.Perpendicular to the section of central axis Z depression area can therefore root It is decreased or increased according to the distance apart from upper surface.In more complicated embodiment, the geometry and area in the section of depression It can change with peripheral surface.The height of depression can also be with peripheral surface and different.Fig. 7 (a) to Fig. 7 (d) is shown Some examples of the geometry of depression.For example, depression can have following shape：(a) parallel to central axis from upper table Prismatic, (c) pyramid (part) that prismatic, (b) of face extension extend perpendicular to central axis from peripheral surface, Or the more complicated volume extended on peripheral surface.

Preferably, depression is typically wedge shape, wherein the first and second depression convergent boundaries be it is straight (slightly inwardly or to Outside sweep) line.The tip of wedge shape corresponds to depression near point and towards the point on the general direction of central axis.Convergent angle θ is in wedge shape Sophisticated place is preferably incorporated between 70 ° and 130 °, more preferably between 80 ° and 110 °, be most preferably 90 ° ± 5 °. This statement used " inside " and " outside " should be interpreted as " direction " or " remote " central axis respectively.

More commonly, the convergence portion of wedge-shaped recess can have one of following geometry：

● the sharp corner of triangular shaped recess is formed, it is corresponding with the wedge-shaped recess discussed before；

● form the straight edge of trapezoidal recess chock；Or

● form the rounded edges wedge shape of arcuate recess.

The utility model further relates to a kind of including the cyclotron of the magnetic pole such as limited before.As described above, circle round Accelerator makes the particle beams accelerate on given path, is driven away until by the particle beams with given energy from cyclotron The first leading point untill.Mound gap portion between a pair of mounds of the first and second magnetic poles of cyclotron has mean height Spend Gh.Preferably, the height Gh of the distance between first and second depression far point 10rdp L10 and mound gap portion ratio bag Include between 1 and 20, preferably between 2 and 10, more preferably between 3 and 5.For example, it is Gh=20- for height 40mm mound gap, distance L10 can be about 10-100mm, so as to produce can be included between 1-5, preferably 3 with Ratio L10/Gh between 3.5, i.e. Gh/L10≤1.

Preferably, leading point is located in the mound gap portion adjacent with the peripheral edge of a pair of relative mound fan blocks.Be recessed position In first leading point downstream, its middle and lower reaches is limited relative to particle beams direction.Relative to leading point and relative to Draw path and accurately machine depression 10 so that the particle beams assembles concave edges 10r1 phases with 90 ° ± 15 ° of angle and first Hand over.Therefore the particle beams leaves mound gap portion substantially perpendicular to magnetic field, which improve the focusing of the particle beams of extraction.Depression Position and geometry are determined by numerical calculation and/or test.

As shown in figure 8, the cyclotron may further include positioned at the first leading point PE1 downstreams and positioned at same The second leading point PE2 in the same mound gap portion of a pair of relative mound fan blocks.Can at second leading point will with The particle beams for having identical energy at first leading point is driven away from cyclotron.In this case, including two The mound fan block of leading point also includes two depressions, and each depression is positioned at corresponding leading point downstream.

Fig. 9 shows the example of the preferred embodiment of the magnetic pole according to cyclotron of the present utility model.In the implementation In example, upper peripheral edge 3up is with distal end on first and second for border, and the upper peripheral edge of mound fan block includes circular arc 3ac, The center of the circular arc is offset relative to central axis and radius Rh is no more than from central axis to the midpoint of upper peripheral edge Distance Lh 85% (Rh/Lh≤85%), the distance of distal end is equal on the midpoint to first and second.

Preferably, radius Rh and distance Lh ratio R h/Lh is no more than 75% (Rh/Lh≤75%), not surpassed more preferably Cross 65% (Rh/Lh≤65%).

The upper peripheral edge having include the purpose of circular arc that its center is offset relative to central axis be at least so that on The part of peripheral edge and spiral path 12 in the mound gap portion 7h of cyclotron highest energy (=it is last ) orbital phase is like approximate.Refer to the circular arc portion and and leading point phase of upper peripheral edge " with the orbital phase like approximate " Adjacent final particle track both of which is to share same center, have the circular arc of different radii.The circular arc is therefore almost parallel In the part close to leading point and at its upstream of the last track.The length and track in the path of extraction orbit with it is upper outer Angle between peripheral edge becomes to be not dependent on the azimuth position of extraction system (for example, stripper).Therefore, the spy of the beam of extraction Sign (almost) is not dependent on the position of leading point.

Preferably, the circular arc distally extends to distal end on second from the first of upper peripheral edge, so as to limit mound fan The whole peripheral edge of block, and the circular arc is centrally located on the bisector of upper surface, the bisector be defined as by The straight line that central axis links with upper peripheral edge.

Preferably, peripheral surface forms the scarf adjacent with upper peripheral edge.

As described above, cyclotron makes the particle beams accelerate on given path, until that can will have given energy The particle beams untill the first leading point that cyclotron drives away.Advantageously, fan block in mound can include more than one draw Go out a little, such as two.Fan the circular arc portion of the upper peripheral edge of block in two mounds opposite relative to mesion MP of two magnetic poles Parallel to the just reproduction part as the given path part of the first leading point upstream and position.The circular arc is whole outer Same center and parallel with it is shared with the part given path in peripheral edge.Term " upstream " and " downstream " be relative to What particle beams direction limited.

When the particle beams has reached its target energy, the particle beams is drawn in leading point and the then particle beams Follow the extraction path in the leading point downstream.Between the first and second magnetic poles and therefore the part in the extraction path Still it is included in the gap portion of mound and is influenceed by magnetic field.Drawn if this includes first and second to relative mound fan block Point, then can be in the first leading point or the second leading point or the extraction particle beams at two leading points.The particle beams is then along One or second leading point downstream first or second draw path.According at least a portion of upper peripheral edge of the present utility model Circular geometry in the case of, be included in the extraction path length L1 in the gap in the first leading point downstream and be included in Extraction path length L2 in the gap of second leading point downstream is substantially identical.

The major advantage in the first and second leading points with identical extraction path length has been to ensure that from a leading point The particle beams of extraction has the light characteristic similar to the particle beams drawn from the second leading point.

Figure 10 (a) and Figure 10 (b) shows the example of the preferred embodiment of the magnetic pole of cyclotron, wherein, at least one The upper surface of individual mound fan block further comprises：

- depression 8, the depression extend depression along the longitudinal axis 8rl intersected with upper peripheral edge and upper center edge Length L8 between near-end 8rpe and depression distal end 8rde；The depression separates its length L8 with the first and second upper edges At least 80%, and

- pole insert 9, the pole insert have the geometry for coordinating the depression and are positioned in the depression And reversibly couple with the depression.

Term " cooperation ", which refers to that pole insert has, can accurately insert the overall shape being nested in the depression.

In the prior art cyclotron including pole insert, pole insert is positioned at from the upper surface of mound fan block In the depression of lateral edges machining.However, the part overlapping with upper edge region of RF acceleration systems makes it difficult to touch To this kind of pole insert.Touch the lap that this kind of pole insert requirement removes RF systems first.By by pole insert Positioning on an upper, can easily and directly touch the pole insert, to remove, machine and reinsert depression In.According to the present embodiment, therefore reach and produce the optimal insert pattern in prediction magnetic field and particle path and be more prone to and efficiently.

Preferably, all pole inserts are of similar shape and are made up of identical material.Preferably, pole insert By being made with corresponding mound fan block identical material.

Preferably, the depression is along the longitudinal axis extension intersected with central axis, and the depression is end at both ends End it is open and extend to upper peripheral edge from upper center edge.In another preferred embodiment, longitudinal axis exists The Dian Chu of distal end equidistance intersects with upper peripheral edge in distance first and second, and wherein, on first and second It is symmetrical that distal end preferably pertains to longitudinal axis.For example, in addition to the portions of proximal 9p adjacent with center edge, pole insert has The generally shape of parallelepiped, as shown in Figure 10 (b).

In Figure 10 (a) embodiment, it is described depression extend to peripheral edge and that be the situation of open-ended Under, pole insert 9dc distal end forms a part for peripheral edge.The part formed by pole insert of upper peripheral edge is excellent Selection of land is no more than 10%, no more than the 5% of the Ah of the length of upper peripheral edge.Preferably, this is distally in peripheral table Scarf is formed at face.

The pole insert is nested in the depression and is reversibly fastened on corresponding mound fan block.It is for example, described Pole insert can be attached to mound fan block using screw 9S.

As previously discussed, pole insert preferably has prism along longitudinal axis in the range of the 80% of its length L9 Geometry, except length is L9p convergence portions of proximal 9p.Ridge between mound upper surface 3U and mound side surface is beveling, Then the corresponding ridge for the portions of proximal being recessed can also be beveling.

It can machine pole insert upper surface 9U's and/or the first and second side surface 9L (being shown in Figure 10 (b)) Pattern is to form upper surface or side surface groove 9gu, 9gl transverse or parallel to longitudinal axis.The groove can be with Extend along straight line, curve or broken line.Alternately, described surface drilling bore hole 9hu, 9hl can be passed through.The hole can be blind hole (that is, there is finite depth) or can be through hole.As explained before, pole is included for symmetry reason, each mound fan block Therefore insert, the pole insert are independent machining or side-by-side alignment and all together mach.Machine adds The gained appearance of pole insert after work can be dramatically different with the aspect before machining.

In a word, the utility model provides the advantage that：Its size for allowing to reduce vacuum chamber and mitigation cyclotron Overall total amount.3rd, it can accurately manufacture the position with locating recesses.4th, magnetic is made by depressed gradient corrector Field caves inward, and so as to cause the finally circulation of particle path inwardly displaced, now compared with close to peripheral edge, magnetic field is more equal It is even.Therefore, the characteristic of the control extraction particle beams and particularly its focusing are easily and more predictable.

Claims

1. one kind is used for the magnetic pole (2) of cyclotron (1), including at least three mound fan block (3) and equal number of including bottom table The paddy fan block (4) in face (4B), the mound fan block and paddy fan block are alternately distributed around central axis Z, and each mound fan block includes：

(a) upper surface (3U) limited by the following：

- upper peripheral edge (3up), the upper peripheral edge with distal end (3ude) on distal end and second on first for border, and Edge that be defined as the upper surface, that position is farthest from the central axis；

- upper center edge (3uc), the upper center edge with near-end (3upe) on near-end and second on first be border and by Edge that be defined to the upper surface, that position is nearest from the central axis；

Distal end on described first is connected by the-the first upper edge (3ul), first upper edge with near-end on described first Connect；

Distal end on described second is connected by the-the second upper edge (3ul), second upper edge with near-end on described second Connect；

(b) the first side surface and the second side surface (3L), each side surface is from first upper edge and the second upper edge The basal surface of the corresponding paddy fan block positioned at the either side of mound fan block is extended transversely to, so as to by under the first lower edge and second Lateral edges (3ll) are defined to the edge for making side surface intersect with adjacent bottom surface, first lower edge and the second lower side Edge each has the position lower distal end farthest from the central axis；

(c) peripheral surface (3P), the peripheral surface extends to lower object-line (3lp) from the upper peripheral edge, described lower outer Contour is defined as the section for border with the lower distal end (3lde) of first lower edge and the second lower edge；

Characterized in that, the upper peripheral edge of at least one mound fan block includes limiting the spill of depression relative to the central axis Part, the depression extend in a part for the peripheral surface of corresponding mound fan block at least in part.

2. magnetic pole according to claim 1, wherein, the depression is generally wedge shape, wherein first assembles line and the Two convergence lines extend outwardly away from the upper peripheral edge with convergent angle θ.

3. magnetic pole according to claim 2, wherein, the convergent angle is included between 70 ° and 130 °.

4. magnetic pole according to claim 3, wherein, the convergent angle is included between 80 ° and 110 °.

5. magnetic pole according to claim 4, wherein, the convergent angle is 90 ° ± 5 °.

6. according to the magnetic pole any one of claim 2-5, wherein, the depression is with the remote upper peripheral edge Convergence portion, the convergence portion have one of following geometry：

● form the anxious turning of triangular shaped recess；

● form the straight edge of trapezoidal recess；Or

● form the rounded edges of arcuate recess.

7. according to the magnetic pole any one of claim 1-5, wherein, the upper peripheral edge has azimuth length Ah, And wherein, the concave portions on described the azimuth length of peripheral edge 3% and 30% between extend.

8. magnetic pole according to claim 6, wherein, the upper peripheral edge has azimuth length Ah, and wherein, institute State concave portions on described the azimuth length of peripheral edge 3% and 30% between extend.

9. according to the magnetic pole any one of claim 1-5, wherein, the upper peripheral edge has azimuth length Ah, And wherein, the concave portions on described the azimuth length of peripheral edge 5% and 20% between extend.

10. magnetic pole according to claim 6, wherein, the upper peripheral edge has azimuth length Ah, and wherein, The concave portions on described the azimuth length of peripheral edge 5% and 20% between extend.

11. according to the magnetic pole any one of claim 1-5, wherein, the upper peripheral edge has azimuth length Ah, And wherein, the concave portions on described the azimuth length of peripheral edge 8% and 15% between extend.

12. magnetic pole according to claim 6, wherein, the upper peripheral edge has azimuth length Ah, and wherein, The concave portions on described the azimuth length of peripheral edge 8% and 15% between extend.

13. according to the magnetic pole any one of claim 1-5,8,10 and 12, wherein, the depression and the described first upside Edge and the second upper edge separate.

14. according to the magnetic pole any one of claim 1-5,8,10 and 12, wherein, the depression and the described first upside Edge is adjacent.

15. according to the magnetic pole any one of claim 1-5,8,10 and 12, wherein, the depression extended the periphery The part corresponding with a part of ζ of the height of the peripheral surface on surface, the height are parallel to the central shaft What line measured on described between peripheral edge and the lower object-line, wherein, the part ζ be included in 25% and 75% it Between.

16. magnetic pole according to claim 15, wherein, the part ζ is included between 40% and 60%.

17. magnetic pole according to claim 16, wherein, the part ζ is included between 45% and 55%.

18. according to the magnetic pole any one of claim 1-5,8,10,12,16 and 17, wherein, the peripheral surface is formed The scarf adjacent with the upper peripheral edge.

19. according to the magnetic pole any one of claim 1-5,8,10,12,16 and 17, wherein, the upper peripheral edge is Circular arc, the center of the circular arc is offset relative to the central axis and radius is no more than from the central axis to described The 85% of the distance at the midpoint of upper peripheral edge, distal end is equal with the distance of distal end on second on the midpoint to described first.

20. according to the magnetic pole any one of claim 1-5,8,10,12,16 and 17, wherein, the number N of mound fan block is 3 It is individual, 4,5,6,7 or 8.

21. magnetic pole according to claim 20, wherein, number N=4 of block are fanned on mound.

22. a kind of cyclotron, it is used on the given path being included in gap make particle accelerate (beamacceleration), and the convolution adds Fast device includes the first magnetic pole and the second magnetic pole, and each in first magnetic pole and the second magnetic pole is according to claim 1-21 Any one of magnetic pole, wherein, first magnetic pole and the second magnetic pole be oriented on first magnetic pole and The mesion that the central axis of two magnetic poles is perpendicular is symmetrical, and the gap is formed between first magnetic pole and the second magnetic pole, its In mound gap portion formed between two relative mounds fan blocks and form paddy gap portion between two relative paddy fan blocks.

23. cyclotron according to claim 22, wherein, the depression has the first depression far point and the second depression Far point, the first depression far point and the second depression far point distance L10 separated from each other, and wherein, first magnetic pole and Mound gap portion between a pair of mounds fan block of second magnetic pole has average height Gh, and wherein, ratio Gh/L10 is included in Between 5% and 100%.

24. cyclotron according to claim 23, wherein, the ratio Gh/L10 be included in 10% and 50% it Between.

25. cyclotron according to claim 24, wherein, the ratio Gh/L10 be included in 20% and 33% it Between.

26. according to the cyclotron any one of claim 22-25, including positioned at first magnetic pole and the second magnetic The first leading point in the gap portion of mound between two opposite upper surfaces of the mound fan block of pole, wherein：

● the given path of the particle beams is that spiral path, the spiral path outwardly surround the central axis outwardly Circulate until the particle beams with given energy can be driven out from the cyclotron along the first extraction path Untill first leading point,

● the depression is located at first leading point downstream, and its middle and lower reaches is limited relative to the particle beams direction, is made

● it is described first extraction path by be included in the angle between 80 ° and 100 ° with it is described be recessed intersect it is corresponding to leave Mound gap portion.

27. cyclotron according to claim 26, wherein the first extraction path by be included in 85 ° with Intersect with the depression to leave corresponding mound gap portion at angle between 95 °.

28. cyclotron according to claim 26, including positioned at limit second draw in the mound fan block in path the Two leading points, and including the second depression positioned at second leading point downstream, so that the second extraction path leads to Cross and intersected with being included in the angle between 80 ° and 100 ° with the described second depression to leave corresponding mound gap portion.

29. cyclotron according to claim 28, wherein the second extraction path by be included in 85 ° with Intersect with the described second depression to leave corresponding mound gap portion at angle between 95 °.

30. cyclotron according to claim 27, including positioned at limit second draw in the mound fan block in path the Two leading points, and including the second depression positioned at second leading point downstream, so that the second extraction path leads to Cross and intersected with being included in the angle between 80 ° and 100 ° with the described second depression to leave corresponding mound gap portion.

31. cyclotron according to claim 30, wherein the second extraction path by be included in 85 ° with Intersect with the described second depression to leave corresponding mound gap portion at angle between 95 °.

32. according to the cyclotron any one of claim 28-31, wherein, first leading point and second is drawn Go out and be a little located in same mound gap portion.