Synchrotron local transverse radio frequency excitation drive resonance slow extraction method and system

Abstract

The invention discloses a synchronous accelerator local transverse radio frequency excitation driving resonance slow extraction method and system. The method comprises the following steps: in a beam extraction process of the synchrotron, applying a transverse radio-frequency excitation signal to a beam only in a preset part of time period in each convolution period of the beam so as to increase the transverse emittance of the beam, and applying a transverse radio-frequency excitation signal to the beam in the rest of time periods of the convolution period so as to increase the transverse emittance of the beam. The transverse radio frequency excitation signal is not applied or the intensity of the transverse radio frequency excitation signal is zero; and leading out the beam with the increased transverse emittance from the synchrotron in a resonance mode. According to the invention, through a mode of only locally applying transverse radio frequency excitation to the beam current in a convolution period, momentum dispersion of the extracted beam current can be effectively reduced, and adverse effects of a space charge effect can be weakened, so that slow extraction efficiency is improved, and key parameters of the extracted beam current, such as a time structure, can be more flexibly controlled.

Description

Technical Field

[0001] The present application relates to the technical field of particle synchrotron resonance slow extraction, and in particular to a method and system for synchrotron local transverse radio frequency excitation driven resonance slow extraction. Background Art

[0002] Particle synchrotron accelerators play a vital role in scientific research and practical applications, with beam extraction being a key technical step. Resonant slow extraction, a beam extraction technique widely used in particle synchrotron accelerators, leverages the resonance effect to continuously and slowly extract beam particles from the accelerator over an extended period. Among various resonant slow extraction methods, third-order resonance driven by sextupole magnets is the most commonly used due to its stability and controllability.

[0003] In the process of third-order resonant slow extraction driven by sextupole magnets, when the sextupole magnets are turned on, a nearly triangular region will be formed in the transverse phase space of the beam, which is usually called the "stable region". Figure 1 , Figure 1 A schematic diagram of the beam's trajectory in the transverse normalized phase space under the influence of a sextupole field in conventional technology. This stable region defines the boundary between stable and unstable particle motion. If a particle's transverse emittance is smaller than the area of ​​this stable region, it will move along the contour lines within the stable region and will not be extracted. Conversely, if the particle's transverse emittance is larger than the area of ​​the stable region, it will move along the contour lines outside the stable region, with its amplitude gradually increasing, ultimately entering a specifically positioned extraction channel for extraction.

[0004] In order to achieve beam extraction, that is, to allow particles to enter the unstable region from the stable region, the existing driving methods can be mainly divided into two categories: one is to reduce the area of ​​the stable region, and the other is to increase the lateral emittance of the beam.

[0005] The area A of the stable region is given by:

[0006]

[0007] where ΔQ is the distance from the synchrotron transverse operating point to the resonance line, and S is the normalized strength of the sextupole magnet.

[0008] Given that the area of ​​the stable region is proportional to the square of ΔQ and inversely proportional to the square of S, changing the area of ​​the stable region can be achieved by varying the strength of ΔQ or S. Among methods for varying ΔQ, adjusting the operating point by adjusting the strength of the quadrupole magnet (quadrupole-driven) is a common approach. Furthermore, due to the chromatic effect, particles of different energies have different operating points. Therefore, by varying the energy of the beam (accelerator-driven), such as by utilizing a betatron core, RF noise, or phase displacement acceleration, to bring the operating point closer to the resonance line, ΔQ, and thus the area of ​​the stable region, can also be reduced.

[0009] Compared with the method of reducing the area of ​​the stable region, the method of increasing the transverse emittance of the beam is more common in practical applications. A typical technology is the radio frequency knockout (RF-Knockout, referred to as RF-KO) technology. This technology continuously increases the transverse emittance of the beam by applying a transverse radio frequency field to the beam. When its emittance exceeds the area of ​​the stable region, the particles will enter the unstable region and be extracted. The significant advantage of the RF-KO technology is that it does not require changing the basic optical properties of the synchrotron accelerator, and can more accurately control the intensity and time structure of the extracted beam. Therefore, it has been widely used in various types of synchrotron accelerators.

[0010] In addition to the above-mentioned driving methods, some other methods have also been developed in recent years, such as the QAR method that combines fast quadrupole iron and RF-KO, and the constant optical slow extraction method (COSE) that keeps the optical properties of the accelerator unchanged.

[0011] In the currently widely used RF-KO technology, in order to continuously excite and increase the lateral emittance of the beam, the frequency of the applied lateral RF excitation signal needs to meet specific resonance conditions with the lateral motion parameters of the beam (such as the fractional part of the working point) and the cyclotron frequency to effectively drive the growth of the lateral emittance of the beam. Figure 2A Under the conventional RF-KO excitation mode shown in the figure (corresponding to the longitudinal phase space of the beam as Figure 2C As shown in FIG, the excitation signal exerts a kicking effect on the entire beam at all times within each cyclotron period of the beam.

[0012] However, this conventional RF-KO technique has some shortcomings. One major problem is that it is difficult to precisely control the momentum dispersion Δp / p of the extracted beam. Usually, the control of the momentum dispersion of the extracted beam is achieved by adjusting the cavity pressure of the main accelerating cavity of the synchrotron. However, due to the limitations of Liu Wei's theorem, the longitudinal emittance of the beam does not change with the change of the accelerating cavity pressure, which leads to a lower limit on the effect of reducing the momentum dispersion by reducing the cavity pressure. For example, in some cases, such as Figure 3 As shown in the left figure, the maximum momentum dispersion of the beam at the end of acceleration (at a higher cavity pressure) can reach 3.50‰; after the acceleration cavity pressure is greatly reduced before extraction, as shown in the figure below: Figure 3 As shown in the figure on the right, the maximum momentum dispersion can only be reduced to about 1.36‰. Even if the cavity pressure is further reduced to zero, the reduction in momentum dispersion is very limited. For applications that require even smaller momentum dispersion, this method of reducing cavity pressure is difficult to meet the requirements.

[0013] Furthermore, when considering the impact of space charge effects on the RF-KO transverse excitation process, large momentum dispersion can lead to reduced slow extraction efficiency, thus affecting the effective utilization of the beam. Therefore, how to effectively control and reduce the momentum dispersion of the extracted beam while maintaining the advantages of RF-KO technology and mitigate the adverse effects of space charge effects is a pressing issue in the field of synchrotron slow extraction technology. Summary of the Invention

[0014] This application proposes a method for resonant slow extraction driven by localized transverse radio frequency excitation in a synchrotron. This method effectively controls and reduces the momentum dispersion of the extracted beam, while maintaining the advantages of RF-KO technology, and mitigates the adverse effects of space charge effects. This application also proposes a corresponding device.

[0015] According to one embodiment of the present application, a method for synchrotron local transverse radio frequency excitation driven resonant slow extraction is proposed, comprising:

[0016] During the beam extraction process of the synchrotron accelerator, a transverse radio frequency excitation signal is applied to the beam during a preset partial time period within each beam cyclotron cycle to increase the transverse emittance of the beam;

[0017] In the remaining time period of each beam cyclotron cycle, not applying the transverse radio frequency excitation signal or making the intensity of the transverse radio frequency excitation signal zero;

[0018] The beam with increased transverse emittance is led out from the synchrotron in a resonance manner.

[0019] In some embodiments, the preset partial time period corresponds to one or more local intervals of the longitudinal phase space of the beam, and the positions of the one or more local intervals are selected based on the target momentum dispersion of the extracted beam to control the momentum dispersion of the extracted beam.

[0020] In some embodiments, the position of the one or more local intervals remains unchanged throughout the slow withdrawal process.

[0021] In some embodiments, the amplitude of the transverse RF excitation signal remains unchanged or changes according to a preset variation when applied to the beam during the preset partial time period.

[0022] In some embodiments, when the transverse RF excitation signal is applied within the preset partial time periods of different beam cyclotron cycles, the amplitude remains unchanged or changes according to a preset variation form.

[0023] In some embodiments, the position of the one or more local sections is changed during the beam extraction process, and the change includes moving the one or more local sections to extract all or most of the beam in the synchrotron.

[0024] In some embodiments, the temporal structure of the extracted beam is controlled by controlling the change in the position of the one or more local intervals.

[0025] In some embodiments, the one or more local intervals are disposed on one side of the longitudinal phase space distribution of the beam.

[0026] In some embodiments, the one or more local intervals are arranged on both sides of the longitudinal phase space distribution of the beam.

[0027] In some embodiments, the frequency f of the transverse RF excitation signal is k The cyclotron frequency f of the beam in the synchrotron rev Satisfies the relationship:

[0028] f k =(N±q f )×f rev ,

[0029] Among them, q f is the fractional part of the synchrotron transverse operating point, and N is an integer.

[0030] According to one embodiment of the present application, a synchrotron system is further proposed, comprising:

[0031] a synchrotron ring, used to contain and accelerate the beam;

[0032] a transverse radio frequency excitation system, configured to apply a transverse radio frequency excitation signal to the beam within the synchrotron ring;

[0033] A control system configured to: during beam extraction from the synchrotron ring, in each cyclotron cycle of the beam, control the transverse RF excitation system to apply the transverse RF excitation signal to the beam during a preset partial time period to increase the transverse emittance of the beam; and control the transverse RF excitation system not to apply the transverse RF excitation signal or to make the intensity of the transverse RF excitation signal zero during the remaining time period of each cyclotron cycle of the beam;

[0034] The synchrotron system is further configured to lead the beam with increased transverse emittance out of the synchrotron ring through resonance.

[0035] Compared with the global excitation method in the prior art in which the transverse RF excitation signal continuously acts on the beam during the entire cycle of the beam cyclotron, the present application applies transverse RF excitation by selecting only a specific local interval of the longitudinal distribution of the beam within one cyclotron cycle, which brings significant technical advantages. First of all, the present application can effectively reduce the momentum dispersion of the extracted beam through local excitation. For example, it can obtain a momentum dispersion value that is far smaller than that which can be achieved by simply reducing the pressure of the acceleration cavity, thereby meeting application scenarios with higher requirements for beam quality. Moreover, since the excitation can act on an area where the spatial distribution of particles is relatively sparse, it can significantly reduce the adverse effects of the space charge effect on the transverse excitation process. Therefore, the present application can significantly improve the overall efficiency of resonant slow extraction and the utilization rate of the extracted beam because it obtains smaller momentum dispersion of the extracted beam and effectively suppresses the space charge effect.

[0036] Furthermore, this application enhances the flexibility and precision of controlling key parameters of the extracted beam. According to this application, the extracted beam with the desired momentum dispersion can be actively controlled by precisely selecting and adjusting the local excitation interval (e.g., the location and range of the interval). Furthermore, by dynamically adjusting this local excitation interval (e.g., moving the interval), the temporal structure of the extracted beam can be effectively controlled, thereby better adapting to diverse experimental or application requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the specification and, together with the description, serve to explain the principles of the specification.

[0038] Figure 1 Schematic diagram of the motion trajectory of the beam in the transverse normalized phase space under the action of the sextupole field in the prior art.

[0039] Figures 2A to 2C The following are a schematic diagram of the global RF-KO excitation waveform of the prior art, a schematic diagram of the waveform of the local RF-KO excitation according to an exemplary embodiment of the present application, and the corresponding beam longitudinal phase space.

[0040] Figure 3 This is a schematic diagram of the beam longitudinal phase space in the prior art, where the left figure shows the state just after acceleration, and the right figure shows the state after the cavity pressure is reduced.

[0041] Figure 4 for Figure 2C A magnified schematic diagram of the longitudinal phase space of a cyclotron cycle.

[0042] Figures 5A to 5C The waveform diagram of the global RF-KO excitation in the prior art, the waveform diagram of the local RF-KO excitation according to the exemplary embodiment of the present application, and the corresponding beam longitudinal phase space diagram are shown in sequence.

[0043] Figures 6A to 6C The following are, in order, a waveform diagram of the global RF-KO excitation of the prior art under higher accelerating chamber pressure conditions, a waveform diagram of the local RF-KO excitation according to an exemplary embodiment of the present application, and a corresponding schematic diagram of the longitudinal phase space of the beam.

[0044] Figure 7 for Figure 6C A magnified schematic diagram of the longitudinal phase space of a cyclotron cycle.

[0045] Figure 8 The figure is a flow chart of a method for driving resonant slow extraction by local transverse radio frequency excitation of a synchrotron according to one embodiment of the present application. DETAILED DESCRIPTION

[0046] Exemplary embodiments will be described in detail herein, with examples illustrated in the accompanying drawings. In the following description, when referring to the drawings, identical numerals in different figures represent identical or similar elements, unless otherwise indicated. The embodiments described in the following exemplary embodiments are not intended to represent all embodiments consistent with the present application. Rather, they are merely examples of apparatus and methods consistent with certain aspects of the present application, as detailed in the appended claims.

[0047] The present application provides a method for synchrotron local transverse radio frequency excitation driven resonance slow extraction. Figure 8 The method mainly includes the following steps 601 to 603.

[0048] Step 601 : During beam extraction from a synchrotron accelerator, a transverse radio frequency excitation signal is applied to the beam during a preset partial time period within each beam cyclotron cycle to increase the transverse emittance of the beam.

[0049] The key to the method of the present application is to provide "local" excitation, that is, the transverse RF excitation does not act on the entire cycle of the beam gyration, but only on a preset, shorter partial time period. This preset partial time period corresponds to one or more local intervals in the longitudinal phase space of the beam. Figure 2A and Figure 2B , Figure 2A The waveform of the global RF-KO excitation in the prior art is shown, which has excitation in the entire cycle. Figure 2B FIG. 3 shows a local RF-KO excitation waveform of an exemplary embodiment of the present application, which has a kick angle intensity only in a very short period of time within a convolution cycle, and the intensity is zero for the rest of the time. Figure 2C Five cyclotron cycles are shown, with the local excitation acting on one side of the beam's longitudinal phase space (dark grey area).

[0050] The transverse RF excitation signal can usually be generated and applied by a RF knock-out (RF-KO) system in a synchrotron. The frequency of the signal f k The cyclotron frequency f of the beam in the synchrotron rev and the fractional part q of the synchrotron operating point f The following resonance conditions can be met:

[0051] f k =(N±q f )×f rev ,

[0052] Wherein, N can be any integer. Those skilled in the art can select a suitable value of N based on accelerator parameters, extraction requirements, etc.

[0053] In some embodiments, the amplitude of the transverse RF excitation signal may remain unchanged when applied to the beam during the predetermined partial time period, such as Figure 2B and Figure 5B In other embodiments, within the preset partial time period of the same convolution cycle, the amplitude of the transverse radio frequency excitation signal may vary according to a preset variation form.

[0054] In some embodiments, the amplitude of the transverse RF excitation signal applied in different cyclotron cycles remains unchanged or changes according to a preset variation.

[0055] Step 602: In the remaining time period of each beam cyclotron cycle, the transverse RF excitation signal is not applied or the intensity of the transverse RF excitation signal is set to zero. Figure 2B As shown, in the non-excited local interval, the kick angle intensity is zero.

[0056] Step 602 further ensures the localization of the excitation, a key technical feature of this application that distinguishes it from traditional global RF-KO. By applying the excitation only in a localized region, disturbances to the overall beam can be minimized, supporting subsequent beneficial effects such as reduced momentum dispersion.

[0057] Step 603: Lead the beam with increased transverse emittance out of the synchrotron accelerator through resonance.

[0058] When the transverse emittance of some particles in the beam increases due to the above-mentioned local transverse RF excitation and exceeds the boundary of the stable region formed by nonlinear elements such as the sextupole field in the transverse phase space (such as Figure 1 After passing through the stable triangle region (shown in the figure), these particles enter the unstable region. Driven by the synchrotron's own dynamics, these unstable particles follow diverging trajectories and eventually enter extraction elements located at specific locations within the accelerator, where they are extracted. This process is known as slow extraction through resonance.

[0059] In general, first, as shown in step 601, during the beam extraction process of the synchrotron accelerator, a transverse RF excitation signal is applied to the beam within a preset partial time period within a beam cyclotron cycle to increase its transverse emittance. Then, as shown in step 602, the transverse RF excitation signal is not applied or its intensity is zero in the remaining time periods within the cyclotron cycle. Steps 601 and 602 together constitute an operating mode for local excitation of the beam within a complete cyclotron cycle. This local excitation mode will run through the entire slow extraction process and will be repeated in multiple cyclotron cycles. Due to the repeated application of step 601, the transverse emittance of a portion of the beam particles will gradually accumulate and increase. Finally, as shown in step 603, these beams with increased transverse emittance are extracted from the synchrotron accelerator through resonance.

[0060] The following further illustrates other details and advantages of the embodiments of the present application in conjunction with the accompanying drawings.

[0061] Reference Figure 4 As shown, it is Figure 2C The enlarged schematic diagram of the longitudinal phase space of a cyclotron cycle in FIG. The preset partial time period corresponds to one or more local excitation intervals in the longitudinal phase space of the beam, that is, Figure 4 The dark gray area in the .

[0062] In some embodiments, one or more local intervals of the beam longitudinal phase space corresponding to the partial time period of applying the transverse RF excitation signal are performed according to the target momentum dispersion of the extracted beam to control the momentum dispersion of the extracted beam.

[0063] According to this embodiment, the momentum dispersion of the extracted beam can be effectively controlled. Figure 4 , which shows that under global RF-KO excitation, the maximum momentum dispersion of the extracted beam is δ p,global , and under the local RF-KO excitation according to the present application, if a suitable local excitation interval is selected (such as Figure 4 The maximum momentum dispersion of the extracted beam can be significantly reduced to δ p,local Compared with the traditional cavity pressure reduction method, which can only obtain a minimum momentum dispersion of about 1.36‰ (such as Figure 3 (As shown in the right figure), the method of this application can achieve a maximum momentum dispersion of no more than 0.806‰, significantly less than the traditional cavity pressure reduction method. Those skilled in the art can optimize the location and width of this localized excitation interval through simulation calculations or experimental debugging based on specific physical requirements and beam parameters to achieve the desired momentum dispersion.

[0064] In some embodiments, the one or more local intervals are arranged on one side of the longitudinal phase space distribution of the beam. Figure 2B and Figure 2C As shown, they all adopt the implementation method of unilateral excitation, and the excitation signal only acts on one end of the particle cluster in the longitudinal phase space within one cyclotron period.

[0065] In other embodiments, the one or more local intervals are arranged on both sides of the longitudinal phase space distribution of the beam. Figure 5B and Figure 5C As shown, one or more local intervals corresponding to the time period of applying the transverse RF excitation signal can also be set on both sides of the longitudinal phase space distribution of the beam. This symmetrical or bilateral excitation method can make the particles more susceptible to the kick angle during their longitudinal motion, thereby improving the efficiency of the transverse emittance growth of the excited beam without changing the maximum momentum dispersion of the extracted beam.

[0066] In addition, when considering the space charge effect, since the excitation acts on the edge area where the particle density is lower, the adverse effects of the space charge force can be better reduced, thereby improving the extraction efficiency.

[0067] In one embodiment, during the entire slow extraction process, the position of the one or more local intervals remains unchanged, so as to adapt to the scenario where particles need to be extracted from a specific phase space region or where there is a very high requirement for the stability of the extracted beam. Figure 4 The dark grey area in ) remains unchanged, then for example Figure 4Particles in the inner region, indicated by the blue solid line, never enter the fixed excitation interval during their entire longitudinal motion and are therefore not affected by the lateral kick angle and thus are not extracted. Therefore, in some cases, using only a fixed excitation interval may not be enough to extract all particles within the accelerator ring.

[0068] In other embodiments, the position of the one or more local intervals changes during the beam extraction process, and the change includes changing the position and range of the one or more local intervals between different cyclotron cycles to extract all or most of the beam in the synchrotron. Figure 4 When the particles in the dark gray area and the light gray area shown in FIG are almost exhausted, the position of the excitation interval is slowly and continuously changed, for example, Figure 4 In the case shown, the local RF-KO excitation interval can be slowly moved to the left. In this way, particles that were not previously covered by the excitation interval (e.g. Figure 4 The particles inside the middle blue line will enter the excitation range one after another as the excitation interval moves, thereby achieving the goal of eliciting all particles in all rings.

[0069] Furthermore, in some embodiments, by controlling the change in the position of the one or more local intervals, for example, controlling the speed of movement, the scanning range, etc., the temporal structure of the extracted beam, that is, the change in the extracted beam intensity over time, can be effectively controlled, thereby providing a more flexible beam control means.

[0070] The synchrotron local transverse radio frequency excitation driven resonant slow extraction method proposed in this application is not only applicable to the stage where the energy remains basically unchanged during the beam extraction process (as shown in Figures 2 and 3 above), but also to the stage where the energy remains basically unchanged during the beam extraction process (as shown in Figures 2 and 3 above). Figure 4 and Figures 5A to 5C The same is also applicable to the case where the energy of the beam is still changing during the extraction process, such as during the acceleration or deceleration extraction stage. The following will take the application of the present invention in the beam acceleration stage as an example, combined with Figures 6A to 6C and Figure 7 Further explanation is provided.

[0071] Figure 6A The waveform of the prior art global RF-KO excitation under a higher accelerating chamber voltage condition (eg, the chamber pressure is maintained at 600 V or a similar high value) is shown as a comparative reference, where the excitation duration in each cyclotron period is relatively long. Figure 6B An exemplary embodiment of the present application is shown in FIG. Figure 6A The waveform characteristics of local RF-KO excitation applied under similar higher accelerating chamber pressure background. Figure 6C It shows that Figure 6BSchematic diagram of the longitudinal phase space of the beam in multiple cyclotron cycles at this higher accelerating cavity voltage, corresponding to the local excitation waveform.

[0072] Figure 7 Shown Figure 6C A magnified schematic diagram of the longitudinal phase space of a cyclotron cycle. Figure 7 It can be observed that at a higher cavity pressure (eg 600 V), the local excitation method according to the present application can still accurately act on a specific local interval of the longitudinal distribution of the beam (eg Figure 7 medium-dark grey area).

[0073] By strictly limiting the transverse RF excitation to a preset local interval in the longitudinal phase space of the beam, the present application can preferentially excite and extract particles within a specific momentum range, thereby significantly reducing the momentum dispersion of the overall extracted beam. For example, compared with the situation where the initial maximum momentum dispersion is 3.50‰ and the traditional cavity pressure reduction method can only be reduced to 1.36‰, the local excitation method proposed in this application can further reduce the momentum dispersion of the extracted beam to 0.806‰ or lower. This strategy of applying excitation only in a local interval within a cyclotron cycle, combined with flexible selection and control of the local excitation interval (including its position, range, number and dynamic changes, etc.), not only effectively solves the inherent limitations of existing RF-KO technology in precisely controlling momentum dispersion, but also helps to reduce the adverse effects of the space charge effect because the excitation acts on areas with relatively low particle density, thereby improving the slow extraction efficiency, and can better regulate the time structure of the extracted beam to meet diverse application needs.

[0074] The present application also provides a synchrotron system, which includes: a synchrotron ring for storing and accelerating a beam; a transverse radio frequency excitation system for applying a transverse radio frequency excitation signal to the beam in the synchrotron ring; and a control system.

[0075] The control system is specially configured to execute the local transverse RF excitation driven resonant slow extraction method described above. The control system can accurately control the transverse RF excitation system so that in each cyclotron cycle of the beam, an excitation signal is applied to the beam only in a preset part of the time period (corresponding to the local interval of the longitudinal phase space of the beam), and no excitation is applied in the remaining time period or the excitation intensity is zero. The control system can be composed of a high-speed programmable logic device (such as an FPGA), a precise timing and synchronization module, and an RF front-end control interface that can generate the required waveform and control its gating. The operator can set the parameters of the local excitation interval through the control system.

[0076] Through the above configuration, the synchrotron system can achieve the various functions and benefits detailed in the method embodiments above, such as effectively reducing momentum dispersion of the extracted beam, weakening space charge effects, improving extraction efficiency, and flexibly controlling the temporal structure of the extracted beam. For other details and advantages of this system, please refer to the detailed description of the method embodiments above and will not be repeated here.

[0077] Finally, it should be noted that the above description is only a preferred embodiment of the present application and is not intended to limit the present application. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein with equivalents. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present application should be included in the scope of protection of the present application. For example, the specific number of local excitation intervals (one or more, for example, when excitation is performed on both sides, it can be considered as two intervals), the specific width and shape of each interval (for example, not just simple rectangular gating, but also excitation of other specific shapes) and the movement mode (for example, continuous scanning, step scanning, nonlinear scanning, etc.) can all be adjusted according to actual needs. Similarly, the specific parameters of the transverse RF excitation signal (such as the exact frequency, amplitude, phase, etc.) also need to be optimized according to the specific parameters of the accelerator and beam. These modifications and variations should fall within the scope of protection of the claims attached to the present application.

[0078] Although this specification includes many specific implementation details, these should not be interpreted as limiting the scope of any invention or the scope of protection claimed, but are mainly used to describe the features of specific embodiments of specific inventions. Certain features described in multiple embodiments within this specification may also be implemented in combination in a single embodiment. On the other hand, the various features described in a single embodiment may also be implemented separately in multiple embodiments or in any suitable sub-combination. In addition, although features may work in certain combinations as described above and even initially claimed as such, one or more features from the claimed combination may be removed from the combination in some cases, and the claimed combination may point to a sub-combination or a variation of the sub-combination.

[0079] Similarly, although operations are depicted in a particular order in the accompanying drawings, this should not be understood as requiring that these operations be performed in the particular order shown or performed sequentially, or that all illustrated operations be performed to achieve the desired results. In some cases, multitasking and parallel processing may be advantageous. In addition, the separation of various system modules and components in the above-described embodiments should not be understood as requiring such separation in all embodiments, and it should be understood that the described program components and systems can generally be integrated together in a single software product, or packaged into multiple software products.

[0080] Thus, specific embodiments of the subject matter have been described. Other embodiments are within the scope of the following claims. In some cases, the actions recited in the claims can be performed in a different order and still achieve the desired results. Furthermore, the processes depicted in the accompanying drawings do not necessarily require the particular order shown or sequential sequence to achieve the desired results. In some implementations, multitasking and parallel processing may be advantageous.

[0081] The above description is merely a preferred embodiment of one or more embodiments of this specification and is not intended to limit one or more embodiments of this specification. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of one or more embodiments of this specification shall be included in the scope of protection of one or more embodiments of this specification.

Claims

1. A method for slow extraction of resonance driven by local transverse radio frequency excitation in a synchrotron, characterized in that: include: During the beam extraction process of the synchrotron accelerator, a transverse radio frequency excitation signal is applied to the beam during a preset partial time period within each beam cyclotron cycle to increase the transverse emittance of the beam; In the remaining time period of each beam cyclotron cycle, not applying the transverse radio frequency excitation signal or making the intensity of the transverse radio frequency excitation signal zero; The beam with increased transverse emittance is led out from the synchrotron in a resonance manner.

2. The method according to claim 1, characterized in that The preset partial time period corresponds to one or more local intervals in the longitudinal phase space of the beam, and the positions of the one or more local intervals are selected based on the target momentum dispersion of the extracted beam to control the momentum dispersion of the extracted beam.

3. The method according to claim 2, characterized in that During the entire slow withdrawal process, the positions of the one or more local intervals remain unchanged.

4. The method according to claim 1 or 2, characterized in that The amplitude of the transverse radio frequency excitation signal remains unchanged or changes according to a preset variation when applied to the beam during the preset partial time period.

5. The method according to claim 1 or 2, characterized in that When the transverse radio frequency excitation signal is applied within the preset partial time periods of different beam cyclotron cycles, the amplitude remains unchanged or changes according to a preset variation form.

6. The method according to claim 2, characterized in that The positions of the one or more local sections are changed during the beam extraction process, and the change includes moving the one or more local sections to extract all or most of the beam in the synchrotron.

7. The method according to claim 6, characterized in that The temporal structure of the extracted beam is controlled by controlling the change in the position of the one or more local intervals.

8. The method according to claim 2, characterized in that The one or more local intervals are arranged on one side of the longitudinal phase space distribution of the beam.

9. The method according to claim 2, characterized in that The one or more local intervals are arranged on both sides of the longitudinal phase space distribution of the beam.

10. A synchrotron system, characterized in that: include: a synchrotron ring, used to contain and accelerate the beam; a transverse radio frequency excitation system, configured to apply a transverse radio frequency excitation signal to the beam within the synchrotron ring; A control system configured to: during beam extraction from the synchrotron ring, in each cyclotron cycle of the beam, control the transverse RF excitation system to apply the transverse RF excitation signal to the beam during a preset partial time period to increase the transverse emittance of the beam; and control the transverse RF excitation system not to apply the transverse RF excitation signal or to make the intensity of the transverse RF excitation signal zero during the remaining time period of each cyclotron cycle of the beam; The synchrotron system is further configured to lead the beam with increased transverse emittance out of the synchrotron ring through resonance.

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