CN111093315A - Isochronous cyclotron with non-dispersive linear segment, and injection and extraction method - Google Patents
Isochronous cyclotron with non-dispersive linear segment, and injection and extraction method Download PDFInfo
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Abstract
The invention discloses an isochronous cyclotron with non-dispersive linear sections, which comprises an injection system and an extraction system which are respectively arranged on a beam curve of the cyclotron, a plurality of periodic magnet assemblies which are arranged at intervals along the direction of the beam curve of the cyclotron and are used for generating at least one group of non-dispersive linear sections and an isochronous magnetic field, non-dispersive linear sections which are arranged along a magnetic field-free space among the plurality of periodic magnet assemblies, and a small-aperture high-frequency acceleration system which is arranged on each non-dispersive linear section; the beam injection method of the isochronous cyclotron with the non-dispersive linear joint is also disclosed, and the required beam energy range is set; selecting energy to be extracted; the accelerator controller allocates the extraction time to the extracted energy and controls the queuing extraction. The invention organically combines different energy and different track characteristics, isochronism characteristics and non-dispersion linear section characteristics, and solves the new technical problem of continuously leading out variable energy within the energy range of the accelerator.
Description
Technical Field
The invention belongs to the technical field of accelerators, and particularly relates to an isochronous cyclotron with a non-dispersive linear section and an injection and extraction method.
Background
In the existing cyclotron, beams with different energies have different orbits, namely, the orbit radius of the beams is gradually enlarged along with the increase of the beam energy until the energy is finally led out. This working principle results in that the cyclotron can only extract the maximum energy fixedly, but not before the beam accelerates to the maximum energy. If beam with other energy is needed, the energy reducer needs to be independently installed to reduce the energy of the extracted beam, although the energy reducer is feasible, the hardware cost is high, and the energy reducer still adopts a method of extracting fixed energy: although the energy is reduced, only one energy is extracted at a time, and the quality of the beam current is also reduced.
In practical application, the requirements for leading out any energy beam in the energy range of the cyclotron are very wide, different products have different requirements for the energy of proton beams, if only one kind of proton beam with fixed energy can be led out, the wide application of the proton beams is influenced, and meanwhile, compared with the cyclotron which can only serve a single requirement, the cost performance is reduced. In addition, the cyclotron in the prior art adopts a method that beams with different energies occupy different tracks, so that the beam tracks cover a certain radial width, the radial length of a high-frequency cavity is increased, the process requirement is high, and the acceleration efficiency is low.
The above-mentioned arbitrary energy beam extraction requirement in the energy range of the cyclotron refers to a continuous extraction requirement, not a discontinuous extraction requirement, and the continuous extraction refers to that a beam reaches specified energy and is extracted in each beam cycle period. In the application of proton accelerators, the average power of pulse beams is low, and good effects are difficult to achieve in the applications of nuclear physics research, isotope production and the like. The continuous beam has the advantages of good uniformity and high average power, and has wide application, such as clinical treatment, and the continuous proton treatment effect is better than the discontinuous proton treatment effect.
Discontinuous random energy beam extraction is called pulse extraction. Although the synchrotron in the prior art can extract beams with any energy in an energy range, the synchrotron is not extracted continuously, and the reason of non-continuity is as follows: the synchrotron only has one track, and the track is equipped with the non-dispersion straight line section, each group of beam current can only be led out after being accelerated from low energy to the led energy on the non-dispersion straight line section of the same track after entering, because the low energy is accelerated to the led energy and needs a waiting time, each led-out is discontinuous, which is called as pulse lead-out, and the pulse lead-out is determined by the innate structure of the synchrotron.
Disclosure of Invention
The invention provides an isochronous cyclotron with a non-dispersive linear section, an injection method and an extraction method aiming at solving the problem that the cyclotron in the prior art can only extract one maximum energy value, but can not select other energy within the range of an extracted energy interval or can extract the required energy by installing an energy reducer.
The invention adopts the following technical scheme to solve the technical problems
An isochronous cyclotron with a dispersion-free linear segment, comprising: the system comprises an injection system and an extraction system which are respectively arranged on a beam curve of a cyclotron, a plurality of periodic magnet assemblies which are arranged at intervals along the direction of the beam curve of the cyclotron and are used for generating at least one group of non-dispersive linear sections and an isochronous magnetic field, non-dispersive linear sections which are arranged in a non-magnetic field space among the plurality of periodic magnet assemblies, and a small-aperture high-frequency acceleration system which is arranged on each non-dispersive linear section; the particles are injected by an injection system on the non-dispersive linear joint of the accelerator, accelerated by the accelerator and finally led out by an extraction system on the non-dispersive linear joint of the accelerator; the non-dispersion linear section is in a linear shape, and different energy beam groups are overlapped on the non-dispersion linear section through tracks and separated outside the non-dispersion linear section through tracks.
The plurality of periodic magnet assemblies for generating at least one group of non-dispersive linear sections are in non-dispersive states at the beam outlet and the beam inlet of each periodic magnet assembly, so that the magnetic field distribution generated by the periodic magnet assemblies meeting the non-dispersive state meets the following requirements:
wherein β(s) is the beam envelope function, p is the orbit curvature radius,
for the phase function, vr is the radial operating point. s1 and s2 indicate the exit and entrance positions of the periodic magnet assembly.
The different energy beam groups are overlapped on the non-dispersive linear section in a track mode, the track overlapping is not overlapped at the same time, and the track overlapping is overlapped in a time sharing mode, namely: different energy beam groups sequentially pass through the track under the control of the accelerator controller.
The plurality of periodic magnet assemblies generating an isochronous magnetic fieldAverage magnetic field distribution along the trackSatisfy the requirement of
The plurality of periodic magnet assemblies for generating the isochronous magnetic field are magnet structures with large track separation quantity, the large track separation quantity means that the distance between the highest energy track and the lowest energy track is large in the distance from the beam inlet to the beam outlet of each periodic magnet assembly, and the magnet structures with large track separation quantity comprise magnetic pole structures, magnetic air gap structures and magnet exciting coils; the magnetic pole structure is a hoof-shaped structure with an opening facing the center of the accelerator and the magnetic poles arranged in the vertical direction, the upper and lower edges of the hoof-shaped structure are helical lines,
the average width of the horseshoe-shaped magnetic pole structure along the radius direction of the accelerator is as follows:
tc is the beam rotation time, vminAnd vmaxVelocity of minimum and maximum energy beam, ImaxAnd IminIs minimum energy beam currentIsochronism error with maximum energy beam; the large track separation amount refers to that the radius of a track operated by the beam is also increased along with the continuous increase of the energy of the beam, and the separation size of the high-energy track and the low-energy track is called as the track separation amount.
The aperture of the small-aperture high-frequency acceleration system is matched with the diameter of a beam group occupying the non-dispersive linear section in a time-sharing manner.
The particles are led out by an extraction system on the non-dispersive linear section of the accelerator, and the extraction system is used for extracting the particles with different energies generated by the accelerator in the acceleration process on the same non-dispersive linear section in a time-sharing manner.
A beam injection method of an isochronous cyclotron with a non-dispersive linear section is characterized by comprising the following steps:
step one, injecting a first beam group into the non-dispersion linear section of the accelerator at the time of 0, and then injecting a beam group into the non-dispersion linear section after each beam circulation period Tc, thereby finally completing the injection of k beam groups.
And step two, after the injection is finished, the beam group injected at the time 0 reaches the required energy, and the beam group with the required energy is extracted at the time k multiplied by Tc through an accelerator control system and an extraction system.
A beam extraction method of an isochronous cyclotron with a non-dispersive linear section is characterized by comprising the following steps:
step one, setting required beam energy:
wherein Emin、EmaxThe minimum and maximum energy of the beam, n is the number of acceleration turns, k is a positive integer and k is less than or equal to the number of acceleration turns.
Step two, selecting the energy required to be led out in the energy range of the step one;
and step three, the accelerator controller distributes leading-out time to the led-out energy and controls the energy particles led out at the time to be queued and led out in the non-dispersion linear section track.
And step four, after the beam current of the current track energy level is led out, a next circle of new particles enter the current track and are continuously distributed at the tail of the led-out particles of the current track, and the new particles are the particles with low speed originally accelerated to the current required energy.
Advantageous effects of the invention
1. The invention organically combines the different energy different orbit characteristics of the cyclotron, the isochronism characteristics of the cyclotron and the non-dispersion linear section characteristics of the synchrotron, and mutually supports and depends the three to obtain unexpected effects, and compared with the single effect before combination, the effect after combination is much superior, thereby solving the new technical problem of continuously leading out variable energy in the energy range of the cyclotron and having outstanding substantive characteristics.
2. The invention reasonably arranges strong and weak magnetic fields in one magnet unit, so that the positions of the beam track at the outlet and the inlet of the magnet unit are independent of the beam energy (i.e. dispersion elimination), thereby forming a non-dispersion linear section, solving the problem that the cyclotron can only lead out fixed energy, and simultaneously reducing the manufacturing difficulty of a high-frequency cavity caused by the radial width of the track by adopting a small-aperture high-frequency system based on the linear section compared with an equidistant large-diameter high-frequency system based on a non-linear section.
3. The invention ensures that the average magnetic field is satisfied
The system has the advantages that the isochronism is realized, and simultaneously, the non-dispersive linear joint is included, so that a high-frequency system with fixed frequency can be adopted, and compared with a high-frequency accelerating system with non-fixed frequency, the high-frequency system with fixed frequency effectively reduces the manufacturing difficulty and the manufacturing cost.
Drawings
FIG. 1 is a single linear-joint cyclotron;
FIG. 2 is a double linear-section cyclotron;
FIG. 3 is a three-line jihui-hui-xian accelerator;
in the figure: 1-1: an injection system; 1-2: leading out the system; 2-1: a single linear segment periodic magnet assembly; 2-2: a double linear segment periodic magnet assembly; 2-3: a three-linear-segment periodic magnet assembly; 3-1: a single linear segment; 3-2: a double straight line section; 3-3: three straight line sections; 4-1: a single straight link high frequency cavity assembly; 4-2: a double straight line section high frequency cavity assembly; 4-3: three-linear-section high-frequency cavity assembly.
Detailed Description
Design principle of the invention
1. The principle of continuously leading out beam current by the isochronous cyclotron. The cyclotron has a plurality of tracks at separated places and is queued by low energy and high energy, so that: after the beam of the current track energy level is extracted, a new particle comes from the next circle, the new particle is the original low-speed particle and is accelerated to the required energy, for example, the energy of the beam extracted from the current track is 100MeV, the energy of the beam in the next circle is 90MeV, after the 100MeV beam is extracted, the 90MeV beam immediately enters the 100MeV track, and the zero waiting time is used in the period, so that the continuous extraction is realized. This is zero latency, first, because parallel work guarantees continuity. The 90MeV track and the 100MeV track work in parallel, the 90MeV track does not accelerate after the beam current of the 100MeV track is led out, but accelerates while the beam current of the 100MeV track is led out, so that after the beam current of the 100MeV track is pumped away, the beam current of the 90MeV track is accelerated to 100MeV and enters the 100MeV track; second, the isochronism of the cyclotron of the present embodiment ensures that the particle continuity is extracted. Isochronism means that the time for one revolution of particles of different energies is equal. That is, the frequency requirement of each energy beam on the high-frequency acceleration system is the same, so that the high-frequency acceleration system with fixed frequency can meet the acceleration requirement of each energy beam.
To summarize: if three conditions are required to achieve continuous extraction of beam rheological energy, first, the accelerator must be a cyclotron with different orbits at different energies, second, it must be an isochronous cyclotron, and third, it has a non-dispersive linear section on the isochronous cyclotron.
2. The principle of achromatic dispersion.
⑴ dispersion is caused by the different deflection of the beam with different energy due to the magnetic field, the beam with high energy is less easily deflected by the magnetic field, so in the prior cyclotron, the beam tracks with different energy are different, we design each periodic magnet assembly composing the accelerator to have the property of dispersion elimination, namely, the position of the beam track at the outlet and the inlet of each periodic magnet assembly is independent of the beam energy, or the positions of the beam with different energy at the outlet and the inlet of each periodic magnet assembly are merged into the same track, namely, the derivative of the beam closed track (rco) at the non-dispersion straight line section to the beam energy is zero:
⑵ the design of the magnet unit of the dispersion elimination is the key point, in the simple ideal magnetic focusing model, the magnetic field distribution of the dispersion elimination can be solved by formula calculation and analysis, however, in the cyclotron, the magnet is a composite magnetic field integrating the functions of deflection and focusing, no analytic solving method is available, and the magnetic field distribution can be solved iteratively only after the dispersion is obtained by numerical values.
⑶ the bunches of different energies pass through the non-dispersive linear joint in turn under the control of the timing system, i.e. the trajectories of the bunches of different energies at the non-dispersive linear joint are overlapping.
⑷ the beam current convolution frequency is f0, the acceleration turns number is n, the frequency of the high-frequency acceleration cavity is n x f0. Every n bunches pass through the non-dispersive linear joint, and one bunch reaches the highest energy and is led out. In the next circle, the beam group is accelerated to the highest energy and is continuously led out. In this process, a low energy beam is injected into the accelerator continuously.
⑸ the so-called variable energy extraction is that since the trajectories of beams of different energies overlap at a non-dispersive linear junction, the beams can be extracted by a deflection magnet without the beam being accelerated to the highest energy.
Based on the principle, the invention designs the isochronous cyclotron with the non-dispersion linear section.
An isochronous cyclotron with non-dispersive linear sections, as shown in fig. 1, fig. 2 and fig. 3, comprises injection and extraction systems (1-1, 1-2) respectively arranged on a cyclotron beam curve, a plurality of periodic magnet assemblies (2-1, 2-2, 2-3) arranged at intervals along the direction of the accelerator beam curve and used for generating at least one group of non-dispersive linear sections and generating an isochronous magnetic field, non-dispersive linear sections (3-1, 3-2, 3-3) arranged in a magnetic field-free space among the plurality of periodic magnet assemblies, and small-aperture high-frequency acceleration systems (4-1, 4-2, 4-3) arranged on each non-dispersive linear section; injecting the particles from an injection system 1-1 on the accelerator non-dispersion linear section, accelerating the particles by the accelerator, and finally extracting the particles from an extraction system 1-2 on the accelerator non-dispersion linear section; the non-dispersion straight line sections (3-1, 3-2 and 3-3) are straight lines, different energy beam groups are overlapped on the non-dispersion straight line sections in a track mode, and tracks outside the non-dispersion straight line sections are separated.
The plurality of periodic magnet assemblies for generating at least one group of non-dispersive linear sections are in non-dispersive states at the beam outlet and the beam inlet of each periodic magnet assembly, so that the magnetic field distribution generated by the periodic magnet assemblies meeting the non-dispersive state meets the following requirements:
wherein β(s) is the beam envelope function, p is the orbit curvature radius,
for the phase function, vr is the radial operating point. s1 and s2 indicate the exit and entrance positions of the periodic magnet assembly.
Supplementary explanation:
1. in the above formula, the left side of the equal sign is a dispersion function, the right side of the equal sign is 0, which represents that the value of the dispersion function is 0, the right side of the equal sign is 0, the 0 represents no dispersion or no dispersion, the concept of no dispersion is graphically described, namely the physical track positions of a plurality of beams are overlapped, the physical track positions are overlapped to indicate that no dispersion occurs, and when the physical tracks of the plurality of beams are separated, the dispersion is called as the dispersion, namely the dispersion occurs. For the example of fig. 1, the beam is not dispersed at the single straight segment 3-1, while dispersion occurs from the entrance to the exit of the beam inside the periodic magnet assembly of 2-1.
2. Rho, β(s) in the dispersion function,
vr, s1 and s2 are dispersion related factors.
P is the radius of curvature of the ideal orbit, since the beam is composed of a large number of non-ideal particles, the characteristics of the magnet assembly for eliminating dispersion should be suitable for the non-ideal particles, and the parameters β of the non-ideal particles are included in the formula,
And vr. wherein the envelope function β(s), phase function
Together determine the location of the non-ideal particles:
describing the amplitude of motion of non-ideal particles on an ideal trajectory, the amplitude being a function of phase
The combination of (a) and (b) characterizes the position of the particles in the accelerator. vr is a radial working point, vr is an important parameter related to track stability, the track stability is the first requirement for the basis of dispersion elimination, and the meaning of vr in the formula is that all work is based on a stable vr. vr describes the number of oscillations of the non-ideal particle around the orbit centerline from the centerline a side to the centerline B side and back to the a side each time the accelerator cycles, which determines whether the orbit diverges easily, and a large degree of orbit divergence will be detrimental to dispersion cancellation. The number of oscillations is not intended to mean a large or small number of oscillations, but rather is an oscillationThe oscillation frequency cannot be an integer, ideally, the oscillation frequency is a decimal oscillation frequency, if the oscillation frequency is an integer, the value of a sine function (sin (n pi)) is 0, and because the magnetic field error exists all the time, the magnetic field error is assumed to be a piece of stone on two sides of the track, and when the sine function is 0, the piece of stone is stepped on each time, so that the results of magnetic field error accumulation and magnetic field accumulation are generated, and the beam current is dispersed and deviates from the central line of the track. The method for overcoming the magnetic field error is to avoid stepping on the same stone every time, and the solution for avoiding stepping on the same stone every time is that the oscillation times cannot be integers and must be numbers with decimal numbers larger than 1 or smaller than 1, so that the sine function values of the numbers with decimal numbers larger than 1 or smaller than 1 are different, the same stone cannot be stepped on if the sine function values are different, the magnetic field error is overcome, and the divergence of beam current is reduced. s1 and s2 indicate the exit and entrance positions of the periodic magnet assembly, meaning that dispersion-free is achieved at s1 and s 2.
For dispersion function please refer to: handbook of Acceliera PhysicandEngineer, page 346
The different energy beam groups are overlapped on the non-dispersive linear section in a track mode, the track overlapping is not overlapped at the same time, and the track overlapping is overlapped in a time sharing mode, namely: different energy beam groups sequentially pass through the track under the control of the accelerator controller.
The plurality of periodic magnet assemblies generating the isochronous magnetic field have a uniform magnetic field distribution along the track
The plurality of periodic magnet assemblies for generating the isochronous magnetic field are magnet structures with large track separation quantity, the large track separation quantity means that the distance between the highest energy track and the lowest energy track is large in the distance from the beam inlet to the beam outlet of each periodic magnet assembly, and the magnet structures with large track separation quantity comprise magnetic pole structures, magnetic air gap structures and magnet exciting coils; the magnetic pole structure is a hoof-shaped structure with an opening facing the center of the accelerator and the magnetic poles arranged in the vertical direction, the upper and lower edges of the hoof-shaped structure are helical lines,
the average width of the horseshoe-shaped magnetic pole structure along the radius direction of the accelerator is as follows:
tc is the beam rotation time, vminAnd vmaxVelocity of minimum and maximum energy beam, ImaxAnd IminThe isochronous error of the minimum energy beam and the maximum energy beam is obtained; the large track separation amount refers to that the radius of a track operated by the beam is also increased along with the continuous increase of the energy of the beam, and the separation size of the high-energy track and the low-energy track is called as the track separation amount.
Supplementary explanation:
three conditions are needed for realizing continuous variable energy extraction beam current, the first cyclotron and the second cyclotron must be cyclotrons with different energies and different orbits, the second cyclotron and the third cyclotron must be isochronous cyclotrons.
The conditions for an isochronous cyclotron are: the average width of the horseshoe-shaped magnetic pole structure in the radial direction of the accelerator must satisfy a value. The above formula is a numerical value for this average width. It is assumed that the non-dispersive linear section of the accelerator is removed, and the remaining high-energy and low-energy arc tracks are spliced into a small closed track. The difference of the average radius of the arc tracks with high energy and low energy is the average width of the horseshoe-shaped magnetic pole structure along the radius direction of the accelerator. Let Ls be the total length of the full-ring non-dispersive linear segment,
average radius of orbit at high energy:
average radius of orbit at low energy:
the radius difference is:
the aperture of the small-aperture high-frequency acceleration system is matched with the diameter of a beam group occupying the non-dispersive linear section in a time-sharing manner.
The particles are led out by an extraction system on the non-dispersive linear section of the accelerator, and the extraction system is used for extracting the particles with different energies generated by the accelerator in the acceleration process on the same non-dispersive linear section in a time-sharing manner.
A beam injection method of an isochronous cyclotron with a non-dispersive linear section comprises the following steps:
step one, injecting a first beam group into the non-dispersion linear section of the accelerator at the time of 0, and then injecting a beam group into the non-dispersion linear section after each beam circulation period Tc, thereby finally completing the injection of k beam groups.
And step two, after the injection is finished, the beam group injected at the time 0 reaches the required energy, and the beam group with the required energy is extracted at the time k multiplied by Tc through an accelerator control system and an extraction system.
A beam extraction method of an isochronous cyclotron with a non-dispersive linear section comprises the following steps:
step one, setting required beam energy:
wherein Emin、EmaxThe minimum and maximum energy of the beam, n is the number of acceleration turns, k is a positive integer and k is less than or equal to the number of acceleration turns.
Step two, selecting the energy required to be led out in the energy range of the step one;
and step three, the accelerator controller distributes leading-out time to the led-out energy and controls the energy particles led out at the time to be queued and led out in the non-dispersion linear section track.
And step four, after the beam current of the current track energy level is led out, a next circle of new particles enter the current track and are continuously distributed at the tail of the led-out particles of the current track, and the new particles are the particles with low speed originally accelerated to the current required energy.
The first embodiment is as follows:
fig. 1 shows a non-symmetric cyclotron with a non-dispersive linear segment, which has the characteristics of large energy span, compactness and low cost, and is suitable for applications with low requirements on beam quality.
Example two:
fig. 2 shows a double-symmetric cyclotron with a non-dispersive linear section, which has a large length of the non-dispersive linear section, is easy for the layout of a high-frequency system and an injection and extraction system, and can accelerate high beam energy.
Example three:
for example, as shown in fig. 3, the triple-symmetric cyclotron with a non-dispersive linear segment can adopt a triple-symmetric structure when a single-turn energy gain is large, and can accommodate more high-frequency acceleration cavities.
The method of the present invention is not limited to the examples described in the specific embodiments, and those skilled in the art can derive other embodiments according to the technical solutions of the present invention, and also belong to the technical innovation scope of the present invention.
The method of the present invention is not limited to the examples described in the specific embodiments, and those skilled in the art can derive other embodiments according to the technical solutions of the present invention, and also belong to the technical innovation scope of the present invention.
Claims (9)
1. An isochronous cyclotron with a dispersion-free linear segment, comprising: the system comprises an injection system and an extraction system which are respectively arranged on a beam curve of a cyclotron, a plurality of periodic magnet assemblies which are arranged at intervals along the direction of the beam curve of the cyclotron and are used for generating at least one group of non-dispersive linear sections and an isochronous magnetic field, non-dispersive linear sections which are arranged in a non-magnetic field space among the plurality of periodic magnet assemblies, and a small-aperture high-frequency acceleration system which is arranged on each non-dispersive linear section; the particles are injected by an injection system on the non-dispersive linear joint of the accelerator, accelerated by the accelerator and finally led out by an extraction system on the non-dispersive linear joint of the accelerator; the non-dispersion linear section is in a linear shape, and different energy beam groups are overlapped on the non-dispersion linear section through tracks and separated outside the non-dispersion linear section through tracks.
2. The isochronous cyclotron with non-dispersive linear segments of claim 1, wherein: the plurality of periodic magnet assemblies for generating at least one group of non-dispersive linear sections are in non-dispersive states at the beam outlet and the beam inlet of each periodic magnet assembly, so that the magnetic field distribution generated by the periodic magnet assemblies meeting the non-dispersive state meets the following requirements:
wherein β(s) is the beam envelope function, p is the orbit curvature radius,
for the phase function, vr is the radial operating point. s1 and s2 indicate the exit and entrance positions of the periodic magnet assembly.
3. The isochronous cyclotron with non-dispersive linear segments of claim 1, wherein: the different energy beam groups are overlapped on the non-dispersive linear section in a track mode, the track overlapping is not overlapped at the same time, and the track overlapping is overlapped in a time sharing mode, namely: different energy beam groups sequentially pass through the track under the control of the accelerator controller.
4. The isochronous cyclotron with non-dispersive linear segments of claim 1, wherein: the plurality of periodic magnet assemblies generating the isochronous magnetic field have a uniform magnetic field distribution along the track
5. The isochronous cyclotron with non-dispersive linear segments of claim 1, wherein: the plurality of periodic magnet assemblies for generating the isochronous magnetic field are magnet structures with large track separation quantity, the large track separation quantity means that the distance between the highest energy track and the lowest energy track is large in the distance from the beam inlet to the beam outlet of each periodic magnet assembly, and the magnet structures with large track separation quantity comprise magnetic pole structures, magnetic air gap structures and magnet exciting coils; the magnetic pole structure is a hoof-shaped structure with an opening facing the center of the accelerator and the magnetic poles arranged in the vertical direction, the upper and lower edges of the hoof-shaped structure are helical lines,
the average width of the horseshoe-shaped magnetic pole structure along the radius direction of the accelerator is as follows:
tc is the beam rotation time, vminAnd vmaxVelocity of minimum and maximum energy beam, ImaxAnd IminThe isochronous error of the minimum energy beam and the maximum energy beam is obtained; the large track separation amount refers to that the radius of a track operated by the beam is also increased along with the continuous increase of the energy of the beam, and the separation size of the high-energy track and the low-energy track is called as the track separation amount.
6. The isochronous cyclotron with non-dispersive linear segments of claim 1, wherein: the aperture of the small-aperture high-frequency acceleration system is matched with the diameter of a beam group occupying the non-dispersive linear section in a time-sharing manner.
7. The isochronous cyclotron with non-dispersive linear segments of claim 1, wherein: the particles are led out by an extraction system on the non-dispersive linear section of the accelerator, and the extraction system is used for extracting the particles with different energies generated by the accelerator in the acceleration process on the same non-dispersive linear section in a time-sharing manner.
8. A beam injection method for an isochronous cyclotron with a non-dispersive linear segment according to claim 1, comprising the following steps:
step one, injecting a first beam group into the non-dispersion linear section of the accelerator at the time of 0, and then injecting a beam group into the non-dispersion linear section after each beam circulation period Tc, thereby finally completing the injection of k beam groups.
And step two, after the injection is finished, the beam group injected at the time 0 reaches the required energy, and the beam group with the required energy is extracted at the time k multiplied by Tc through an accelerator control system and an extraction system.
9. A method for extracting beam current of an isochronous cyclotron with a non-dispersive linear segment according to claim 1, comprising the following steps:
step one, setting required beam energy:
wherein Emin、EmaxThe minimum and maximum energy of the beam, n is the number of acceleration turns, k is a positive integer and k is less than or equal to the number of acceleration turns.
Step two, selecting the energy required to be led out in the energy range of the step one;
thirdly, the accelerator controller distributes leading-out time to the led-out energy and controls the energy particles led out at the time to be queued and led out in the non-dispersion linear section track;
and step four, after the beam current of the current track energy level is led out, a next circle of new particles enter the current track and are continuously distributed at the tail of the led-out particles of the current track, and the new particles are the particles with low speed originally accelerated to the current required energy.
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| CN112954877A (en) * | 2021-01-29 | 2021-06-11 | 黄正曦 | Device and method for generating electromagnetic energy by uniform linear motion charge |
| CN113202707A (en) * | 2021-05-12 | 2021-08-03 | 兰州空间技术物理研究所 | Diameter-variable ion thruster magnetic pole |
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| CN111093315B (en) | 2020-11-17 |
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