CN221058480U - Deflection magnet and deflection device - Google Patents

Abstract

The utility model belongs to the field of particle accelerators, and particularly relates to a deflection magnet and a deflection device. Comprises an outer iron yoke, an excitation structure and a pole head; the outer iron yoke is provided with a beam outflow inlet, two pole heads are symmetrically arranged in the outer iron yoke, an excitation structure is arranged outside the two pole heads, and a working air gap is formed between pole faces of the two pole heads; the pole face comprises an incidence area, a achromatic area and an emergent area, the distance between two pole heads of the incidence area is equal to the distance between two pole heads of the emergent area, and the distance between two pole heads of the incidence area is larger than the distance between two pole heads of the achromatic area.

Description

Deflection magnet and deflection device

Technical Field

The utility model belongs to the field of particle accelerators, and particularly relates to a deflection magnet and a deflection device.

Background

The beam in the particle accelerator needs to deflect, when the deflection angle is large, the beam can be dispersed widely, and larger dispersion can be generated after deflection, so that the subsequent transmission or application is not facilitated. In order to reduce dispersion caused by deflection, a combination of a plurality of deflection magnet elements is generally required to achieve the dispersion eliminating effect.

Deflection magnets are used in industry to redirect particle transport to meet process demands, such as: irradiation processing, irradiation sterilization, industrial detection, imaging and the like for industrial application.

In a deflection magnet without a achromatic design, particles with different energies are separated in track and deflection angle after passing through, namely, the deflection magnet gives dispersion to the beam current. At the same time, the larger the deflection angle, the more pronounced this dispersion. In order to realize dispersion elimination, the prior art generally uses a plurality of deflection magnet elements to combine, so that the dispersion brought by a single deflection magnet to the beam is offset back and forth, and the total deflection angle of the plurality of combinations is equal to the deflection angle required by the system. Such a decolored deflection yoke comprising a plurality of deflection magnet elements is generally large in size.

In view of this, the present utility model has been made.

Disclosure of utility model

In order to solve the technical problems in the prior art, the utility model provides a deflection magnet and a deflection device, and the deflection magnet structure can realize larger-angle decoloration and dispersion deflection on a single deflection magnet element, is more compact in size, is more flexible to arrange on an accelerator transport line, and is lower in construction and operation cost.

The utility model comprises the following technical scheme:

The first aspect of the utility model provides a deflection magnet comprising an outer iron yoke, an excitation structure and a pole head; the outer iron yoke is provided with a beam outflow inlet, two pole heads are symmetrically arranged in the outer iron yoke, an excitation structure is arranged outside the two pole heads, and a working air gap is formed between pole faces of the two pole heads; the pole face is of an axisymmetric structure, the pole face comprises an incident area, a achromatic area and an emergent area, the distance between two pole heads of the incident area is equal to the distance between two pole heads of the emergent area, and the distance between two pole heads of the incident area is larger than the distance between two pole heads of the achromatic area.

Further, the boundary line between the incidence area and the achromatic area is a curve; and/or the boundary line between the emergent area and the achromatic area is a curve.

Further, the excitation structure is an excitation coil or a permanent magnet.

Further, the beam deflection angle in the achromatic region is 45-90 degrees.

Further, the ratio of the distance between the two polar heads of the incident area to the distance between the two polar heads of the achromatic area is 4: 3-2: 1.

Further, an energy slit is provided between the achromatic regions of the two poles, the energy slit being used to control the energy of the passing beam.

Further, the energy slit is composed of a first beam limiting structure and a second beam limiting structure, and a gap between the first beam limiting structure and the second beam limiting structure is the energy slit.

Further, the size of the energy slit may be adjustable.

Further, the first beam limiting structure is composed of copper, aluminum and/or tungsten; the second beam limiting structure is composed of copper, aluminum and/or tungsten.

A second aspect of the present utility model provides a deflection apparatus comprising:

A deflection magnet, which adopts the above-mentioned deflection magnet;

And the vacuum chamber body is arranged in the magnetic field space generated by the deflection magnet.

By adopting the technical scheme, the utility model has the following advantages:

1. For a required specific deflection angle smaller than 180 degrees, the total deflection angle of the single magnet is larger than 180 degrees, and the deflection angle of the whole magnet is still the required specific deflection angle; the deflection magnet divides three areas on the pole face of the pole head, comprises a achromatic area and compensates for different deflection tracks caused by different energies, thereby realizing the achromatic deflection with larger angle on the single deflection magnet element and enabling the size of the deflection system to be more compact.

2. In industrial production, the beam current with different energy requirements can be used by adjusting the size of the energy slit, so that the same production line can meet different production requirements, the application range of the industrial accelerator is improved, and the production cost is reduced.

3. Compared with an energy selection system formed by combining a plurality of groups of deflection magnets and energy slits, the energy slits are positioned at the achromatic area of the deflection magnets, and are not required to be arranged outside the deflection magnets or introduce additional chromatic dispersion eliminating elements, so that the function of energy selection is realized in a compact space.

4. Compared with the boundary between the incidence area and/or the emergent area and the achromatic area being straight or other linear, the boundary between the incidence area and the achromatic area is a curve; and/or the boundary line between the emergent region and the achromatic region is a curve; has better achromatic effect.

5. Compared with other designs with the central energy deflection angle of the achromatic region being 90 degrees or more, the central energy deflection angle of the achromatic region is 45 degrees to 90 degrees; facilitating a more compact pole head design and providing a more relaxed vacuum box space.

6. Compared with the design that the distance between the two polar heads of the incidence area and the distance between the two polar heads of the achromatic area are larger, the ratio of the distance between the two polar heads of the incidence area and the distance between the two polar heads of the achromatic area is 4: 3-2: 1, a step of; the requirements for the excitation module are lower, so that the weight and the power consumption of the whole magnet are reduced conveniently.

7. The application range of the utility model can comprise irradiation processing, irradiation sterilization, industrial detection and imaging of industrial application, radionuclide pharmacy targeting of medical application, medical imaging, fixed beam or rotating frame of radiotherapy and the like.

8. The utility model is especially suitable for industrial application, and in industrial application, the deflected beam is transmitted through the beam line, so that the dispersion degree of the deflected beam greatly influences the subsequent beam line transmission, and the beam emitted by the deflected deflection magnet can meet the beam line transmission.

Drawings

In order to more clearly illustrate the embodiments of the present utility model or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described, and it is obvious that the drawings in the following description are some embodiments of the present utility model, and other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

FIG. 1 is a schematic diagram of a deflection magnet according to an embodiment of the present utility model;

FIG. 2 is a cross-sectional view taken along A-A of FIG. 1;

FIG. 3 is a schematic view of a partial structure of a deflection magnet according to an embodiment of the present utility model;

FIG. 4 is a partial schematic view of FIG. 3;

FIG. 5 is a schematic view of a pole head according to an embodiment of the present utility model;

FIG. 6 is a second schematic structural view of a pole head according to an embodiment of the present utility model;

FIG. 7 is a schematic diagram of a deflection trajectory of a beam in an embodiment of the present utility model;

FIG. 8 is a schematic diagram of a central energy trace of a beam in an embodiment of the present utility model;

FIG. 9 is a second schematic diagram of a central energy trace of a beam in an embodiment of the present utility model;

In the figure: 10-outer yokes, 11-upper yokes, 12-lower yokes, 101-beam outflow inlet, 102-linear driving structure moving port, 103-beam outflow outlet; 20-excitation structure, 30-pole head, 301-incidence area, 302-achromatic area, 303-emergent area, 40-working air gap, 50-boundary line, 60-energy slit, 70-first beam limiting structure, 80-second beam limiting structure, and 90-linear driving structure.

Detailed Description

The following description provides many different embodiments, or examples, for implementing different features of the utility model. The elements and arrangements described in the following specific examples are presented for purposes of brevity and are provided only as examples and are not intended to limit the utility model.

In the description of the present utility model, the terms "first," "second," and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include one or more of the described features.

For the purpose of making the objects, technical solutions and advantages of the embodiments of the present utility model more apparent, the technical solutions of the embodiments of the present utility model will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present utility model, and it is apparent that the described embodiments are some embodiments of the present utility model, but not all embodiments of the present utility model. All other embodiments, which can be made by those skilled in the art based on the embodiments of the utility model without making any inventive effort, are intended to be within the scope of the utility model.

The present embodiment provides a deflection magnet, as shown in fig. 1 to 6, comprising an outer yoke 10, an exciting structure 20 and a pole head 30; the outer yoke 10 is provided with a beam outflow inlet 101, two pole heads 30 are symmetrically arranged in the outer yoke 10, an excitation structure 20 is arranged outside the two pole heads 30, and a working air gap 40 is formed between pole faces of the two pole heads 30; the pole face is in an axisymmetric structure, the pole face comprises an incident area 301, a achromatic area 302 and an emergent area 303, the distance between two pole heads 30 of the incident area 301 is equal to the distance between two pole heads 30 of the emergent area 303, and the distance between two pole heads 30 of the incident area 301 is larger than the distance between two pole heads 30 of the achromatic area 302.

The outer yoke 10 includes an upper yoke 11 and a lower yoke 12, and the beam outflow inlet 101 on the outer yoke 10 is both an inlet for beam current and an outlet for deflected beam current.

In the prior art, the small-angle deflection of the beam is mostly deflected by 90 degrees, and the beam needs to deflect by 270 degrees in the deflection magnet, which is a large-angle deflection with serious dispersion; as shown in fig. 5, the pole face of the pole head 30 is designed to have an effect of eliminating beam dispersion. As shown in fig. 7, a schematic diagram of the theoretical trajectory and theoretical pole face is as follows:

In the figure, the pole face of the pole head 30 is divided into three regions, region1 (incident Region 301), regi on (achromatic Region 302), regi on (exit Region 303), according to the order in which the beam passes. Wherein regi on1 and Regi on are symmetrical about a Symmetry plane, mechanically the same plane. Beamin and Beam out are directions of Beam injection and extraction, respectively, and the Beam is deflected 270 ° in the achromatic deflection magnet.

The deflection magnet is generally a diode magnet structure, and a diode magnetic field perpendicular to the beam transport direction is formed between a pair of coils and pole heads which are arranged in parallel, so that moving charged particles can be subjected to lorentz force:

F＝qvB

Where F is the lorentz force, q is the charge carried by the particle, v is the velocity of the particle, and B is the magnetic field strength. The particles are deflected by lorentz forces. The deflection radius is:

Wherein R is the deflection radius, W is the kinetic energy of the particle, ε ₀ is the static energy of the particle, and c is the speed of light. Therefore, the deflection radius is different when the energy is different. When a beam having a wider energy spread passes through the same deflection magnet, the deflection trajectories of particles of different energies are different.

In this example, the following settings were made:

Setting Regi on an air gap of 2/3 of Regi on and Reg i on 3; thus, regi on has a magnetic field strength 1.5 times that of Regi on and Regi on. According to

The radius of deflection of a particle in Reg i on2 is 2/3 of Reg i on1 and Reg i on 3.

The set magnet is suitable for the beam with the central energy of 2MeV and can scatter +/-10%. The energy of the reference beam illustrated in the figure is E0 as the center energy, 2MeV; EH is a higher upper energy limit, 2.2MeV; EL is a lower energy limit of 1.8MeV.

The central energy is deflected by 105 ° in Regi on & 1&3 and by 270 ° -105 ° =60° in Regi on 2. I.e. the sum is 270. The angles are set for the design, and each specific angle corresponds to a design example of one pole head.

A special case can then be solved based on the assumptions above. First, according to the above formula, assuming that the energy and the magnetic field intensity of each region are listed, the deflection radius of each region corresponding to each energy can be calculated as follows:

consider the geometry corresponding to the dispersion cancellation condition:

(1) The ideal track is symmetrical by taking a 45-degree axis as a symmetry plane, so that 135 degrees of deflection magnet is solved. In half of the tracks, the incidence is a vertical boundary crossing the origin, and the emergence is a 45-degree inclined boundary crossing the origin. The incidence angle and the emergence angle are respectively perpendicular to the incidence vertical boundary and the emergent symmetry axis boundary, namely the total deflection angle is 135 degrees.

(2) The beam is continuous and in theory it is believed that the magnetic field is abrupt and therefore the deflection radius is abrupt as the beam passes the junction of Reg i on1 and Regi on. So that two circular arcs of the same energy are tangent.

(3) Any tangent line on the circular arcs is vertical to the radius, so that the tangent point P1 of the circular arcs at the two ends is collinear with the three points of the circle center C1m of the first section of circular arc and the circle center C2m of the second section of circular arc.

The first step draws a trace of the center energy. As shown in fig. 8:

The coordinates of C1m are calculated from trigonometric functions under this coordinate system. Deflection radius:

r1m=300 mm, r2=200 mm; deflection angle: θ1m=105°, θ2m=135° -105 ° =30°. The coordinates of C1m are:

x1m＝0 (mm)

y1m＝(R1m-R2m)*[sin(θ1m)+cos(θ1m)]

＝100*(0.9659-0.2588)＝70.71 (mm)

In the coordinate system, the y coordinate of the incident point is R1m-y1m.

Next, traces of other energies are drawn one by one. Taking the upper energy limit EH as an example, the deflection radii thereof have been previously found to be r1h=314.44 mm, r2h= 209.63mm, respectively; since the respective energies are incident from the same point, the incident point is still the just-obtained (0, R1-y 1 m). The trajectory of the EH energy also needs to satisfy the geometric conditions (1), (2), (3).

Θ1h is solved as follows:

Based on the geometric relationship, the equation is listed as:

(R1h-R2h)*[cos(θ1h-90°)-sin(θ1h-90°)]

＝[R1h-(R1m-y1m)]

In this example: 104.81 [ cos (θ1h-90 °) -sin (θ1h-90 °) ] =85.15 solving the equation yields θ1h=99.94 °. θ2h is θ2h=135° - θ1h= 35.06 °. As shown in fig. 9.

The deflection angles corresponding to the respective energies are obtained one by one, as shown in the following table.

After the deflection angle is obtained, the tangent points of the two sections of curves corresponding to each energy are determined, and all the tangent points are connected together, namely the theoretical polar surface boundary line 50. Calculating the parameters in the mode, wherein the theoretical polar surface boundary lines 50 are all curves; it can be derived from this that, in some embodiments, on the basis of improving the achromatic effect, as shown in fig. 5 and 6, the boundary line 50 between the incident area 301 and the achromatic area 302 is a curve; the boundary line 50 between the emission region 303 and the achromatic region 302 is a curve.

In some embodiments, as shown in fig. 5 and 6, the pole head has an axisymmetric structure. Based on this, there is an advantage of easy manufacturing.

In some embodiments, the excitation structure 20 is an excitation coil or a permanent magnet.

In some embodiments, the beam deflection angle in the achromatic region 302 is 45 ° to 90 °. The beam deflection angle of 45 ° to 90 ° should include the end points of 45 ° and 90 °.

In some embodiments, the ratio of the distance between the two poles of the incident area 301 to the distance between the two poles of the achromatic area 302 is 4: 3-2: 1. note that, range 4: 3-2: 1 should include endpoint 4:3 and 2:1.

In some embodiments, an energy slit 60 is provided between the achromatic regions 302 of the two poles 30, the energy slit 60 being used to control the energy of the passing beam. Thereby enabling selection of energy in a compact space.

In some embodiments, as shown in fig. 5, the energy slit 60 is composed of a first beam limiting structure 70 and a second beam limiting structure 80, and a gap between the first beam limiting structure 70 and the second beam limiting structure 80 is the energy slit 60. It should be noted that other configurations of the energy slit 60 are also within the scope of the present utility model

In some embodiments, the size of the energy slit 60 may be adjustable.

The size of the energy slit 60 can be adjusted according to the industrial production requirements, i.e. the size of the energy slit 60 is adjusted according to the energy of the required beam.

In some embodiments, as shown in fig. 3 and 4, the first beam limiting structure 70 and the second beam limiting structure 80 are connected to a linear driving structure 90, and a beam limiting window is disposed on the first beam limiting structure 70, and the beam limiting window can be used as the energy slit 60; in this structure, the second beam limiting structure 80 cooperates with the beam limiting window to achieve the purpose of adjusting the size of the energy slit 60. It should be noted that the specific structure of the specific adjusting energy slit 60 is a specific example of an embodiment, and other forms of adjusting structures should be within the scope of the present utility model.

In some embodiments, the linear driving structure 90 is a mechanical transmission structure, the driving part of the linear driving structure 90 is arranged outside the outer iron yoke 10, as shown in fig. 3 and 4, and meanwhile, a linear driving structure movable opening 102 for moving the driving shaft of the linear driving structure 90 is arranged on the outer iron yoke 10; this makes it possible to make the size of the deflection magnet more compact.

In some embodiments, as shown in fig. 3, the outer yoke 10 is further provided with a beam outlet 103, and when the excitation mechanism is turned off, the beam is not deflected, and the beam is emitted through the beam outlet 103; this can improve the applicability of the deflection magnet.

In some embodiments, the first beam limiting structure 70 is comprised of copper, aluminum, and/or tungsten; the second beam limiting structure 80 is comprised of copper, aluminum, and/or tungsten.

The present embodiment also provides a deflection apparatus including:

A deflection magnet as described above;

And the vacuum chamber body is arranged in the magnetic field space generated by the deflection magnet.

It should be noted that, the beam current described in the present utility model includes electron beam, proton beam, heavy ion beam, and the like.

Although the utility model has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present utility model.

Claims (10)

1. A deflection magnet, characterized by comprising an outer iron yoke (10), an excitation structure (20) and a pole head (30); the outer iron yoke (10) is provided with a beam outflow inlet (101), two pole heads (30) are symmetrically arranged in the outer iron yoke (10), an excitation structure (20) is arranged outside the two pole heads (30), and a working air gap (40) is formed between pole faces of the two pole heads (30); the pole face is of an axisymmetric structure, the pole face comprises an incidence area (301), a achromatic area (302) and an emergent area (303), the distance between two pole heads (30) of the incidence area (301) is equal to the distance between two pole heads (30) of the emergent area (303), and the distance between two pole heads (30) of the incidence area (301) is larger than the distance between two pole heads (30) of the achromatic area (302).

2. A deflection magnet according to claim 1, wherein the boundary (50) between the incidence area (301) and the achromatic area (302) is curved; and/or the boundary (50) between the emission region (303) and the achromatic region (302) is curved.

3. A deflection magnet according to claim 1, wherein the field structure (20) is a field coil or a permanent magnet.

4. A deflection magnet according to claim 1 or 2, characterized in that the beam deflection angle in the achromatic region (302) is 45 ° to 90 °.

5. A deflection magnet according to claim 1, wherein the ratio of the distance between the two poles of the incidence area (301) to the distance between the two poles of the achromatic area (302) is 4: 3-2: 1.

6. A deflection magnet according to claim 1, characterized in that an energy slit (60) is provided between the achromatic regions (302) of the two pole heads (30), said energy slit (60) being used for controlling the energy of the passing beam.

7. A deflection magnet according to claim 6, wherein the energy slit (60) is formed by a first beam limiting structure (70) and a second beam limiting structure (80), the gap between the first beam limiting structure (70) and the second beam limiting structure (80) being the energy slit (60).

8. A deflection magnet according to claim 6, wherein the size of the energy slit (60) is adjustable.

9. A deflection magnet according to claim 7, wherein the first beam limiting structure (70) is composed of copper, aluminum and/or tungsten; the second beam limiting structure (80) is composed of copper, aluminum and/or tungsten.

10. A deflection apparatus, comprising:

A deflection magnet employing a deflection magnet according to any one of claims 1 to 9;

And the vacuum chamber body is arranged in the magnetic field space generated by the deflection magnet.