A transversal feedback system with switchable excitation direction and a control method thereof

Abstract

The present application relates to the technical field of particle accelerator, and especially relates to a transverse feedback system with switchable excitation direction and a control method thereof, which comprises: a beam position probe (BPM) for measuring a beam signal; an RF front end for receiving the beam signal sent by the beam position probe (BPM) and performing amplification and filtering processing; an ADC module for converting the beam signal into a digital signal; a digital signal processing module for performing digital signal processing calculation to obtain an excitation signal; a DAC module for performing digital-to-analog conversion; a power divider for adjusting the phase of the excitation signal; and a kicker including four charged electrodes, a power amplifier, a low-pass filter and a matching load for applying a transverse excitation signal to the beam. The present application solves the problems of the prior art, such as large occupation of longitudinal space by the transverse feedback system (Kicker), complex system, low precision and low efficiency.

Description

Technical Field

[0001] This invention relates to the field of particle accelerator technology, and in particular to a transverse feedback system with switchable excitation direction and its control method. Background Technology

[0002] In particle accelerators, the transverse feedback system is a key device for suppressing beam instability and ensuring high-quality beam operation. This system measures the transverse oscillations of the beam using a beam position detector (BPM) and applies an electromagnetic field to the beam using a kicker to counteract the oscillations.

[0003] Currently, the main kicker scheme for achieving lateral feedback excitation is the dual-electrode kicker scheme, typically employing a pair of parallel plates or strip wire electrodes. The advantage of this scheme is its simple structure, but its excitation direction is fixed. If simultaneous feedback in both the horizontal (X) and vertical (Y) directions is required, two independent kickers must be installed on the accelerator ring—one horizontally and one vertically. Furthermore, due to the larger oscillation amplitude generated by the vertical insert during light supply, two vertical kickers are usually installed as well, resulting in a combination of one horizontal and two vertical kickers. This not only occupies valuable vertical installation space but also increases the cost of the equipment and the complexity of the system.

[0004] In situations where longitudinal installation space is insufficient, a few devices employ a four-electrode kicker scheme, where four electrodes are symmetrically placed in pairs around the beam channel, such as C-shaped electrodes placed horizontally and flat plates placed vertically. In existing technologies, to simultaneously excite the X and Y directions, diagonal excitation or adjacent electrode combinations are typically used. For example, specific signal combinations can simultaneously generate horizontal and vertical electric field components on the four electrodes. However, this simultaneous excitation method has a significant drawback: the electromagnetic fields in the X and Y directions are prone to coupling interference. The excitation field in one direction may generate unnecessary field components in the orthogonal direction, thus affecting the beam motion in the other direction and reducing the accuracy and efficiency of the feedback system. Summary of the Invention

[0005] The purpose of this invention is to provide a lateral feedback system with switchable excitation direction and its control method, thereby solving the problems of low accuracy and efficiency of existing feedback systems.

[0006] To achieve the above objectives, the present invention provides a lateral feedback system with switchable excitation direction, comprising:

[0007] The beam position detector (BPM) is used to measure the beam oscillation signal and transmit it to the RF front end.

[0008] The RF front end is electrically connected to the beam position detector (BPM) and is used to receive the beam signal sent by the BPM, amplify and filter it, and then send it to the ADC module.

[0009] The ADC module, electrically connected to the RF front end, is used to convert the beam signal into a digital signal and send it to the digital signal processing module.

[0010] The digital signal processing module, electrically connected to the ADC module, is used to perform digital signal processing calculations, obtain excitation signals, and send them to the DAC module.

[0011] The DAC module, electrically connected to the digital signal processing module, is used to perform digital-to-analog conversion and send the data to the power divider.

[0012] The power divider, electrically connected to the DAC module, is used to adjust the phase of the signal applied to different strips and send it to the exciter;

[0013] The exciter, including a power amplifier, a low-pass filter, four stripe electrodes (Kicker), and a matching load, is used to apply transverse feedback excitation to the beam.

[0014] In some embodiments of this application, both the beam position detector (BPM) and the strip electrode are positioned at points where the β function is large, thereby maximizing the amplitude of the oscillation signal.

[0015] In some embodiments of this application, the matching load is 50Ω and is electrically connected to the upstream port of the four-strip electrode for signal matching; the four-strip electrode includes electrodes composed of four strips A, B, C, and D.

[0016] In some embodiments of this application, the power amplifier and the low-pass filter are used to amplify the phase-adjusted analog signal and filter out high-frequency noise, respectively. The low-pass filter is electrically connected to the downstream ports of the four electrodes.

[0017] In some embodiments of this application, the operating modes of the lateral feedback system include vertical mode and horizontal mode;

[0018] In vertical mode, excitation signals with equal amplitudes and phases of 180°, 180°, 0°, and 0° are applied to A, B, C, and D, respectively. Due to the symmetry of the boundary conditions, the excited electric field is along the vertical direction, and the excited magnetic field surrounds the vertical direction. The cluster near the center experiences a superposition of electric and magnetic forces in the vertical direction, expressed as:

[0019] F = q(E + v × B);

[0020] In horizontal mode, excitation signals with equal amplitude and phases of 0, 180, 180, and 0 are applied to A, B, C, and D respectively. Its working principle is the same as that of vertical mode. The electromagnetic field direction of vertical mode is rotated by 90°, and the excitation of the bundle near the center becomes horizontal.

[0021] In some embodiments of this application, a control method for a lateral feedback system with switchable excitation direction is also disclosed, comprising the following steps:

[0022] S1. Configure a lateral feedback system;

[0023] S2. When the beam disturbance mainly comes from the horizontal direction, the control lateral feedback system is set to operate in horizontal mode to suppress the horizontal oscillation of the beam.

[0024] S3. When the beam disturbance mainly comes from the vertical direction, the control lateral feedback system operates in vertical mode to suppress the vertical oscillation of the beam.

[0025] In some embodiments of this application, in S1, the configuration of the lateral feedback system includes:

[0026] a. In the lateral feedback system, two two-electrode kickers and one four-electrode kicker are set up. The two-electrode kickers are used for fixed horizontal or vertical directions, and the four-electrode kickers are selectively excited according to the actual operating mode.

[0027] Specifically, in configuration a, two-electrode kickers in the horizontal or vertical direction work together with four-electrode kickers to jointly undertake the beam feedback task; through power sharing, the driving power required by a single kicker can be significantly reduced, thereby reducing the power level requirement of a single power amplifier; since the cost of power amplifiers increases significantly with power, this configuration can effectively reduce system costs while ensuring performance.

[0028] b. Set up three four-electrode kickers in the lateral feedback system. Each four-electrode kicker can be selectively excited according to the actual operating mode.

[0029] Specifically, compared with the traditional two-electrode scheme, the b configuration can reduce the system complexity caused by the mixing of different types of kickers; since the direction of each kicker can be electronically switched, when one kicker fails, another kicker can switch to the corresponding mode through phase adjustment, thereby achieving functional replacement and improving system redundancy and reliability; the system structure is more unified and installation and maintenance are more simplified.

[0030] c. Given the limited vertical installation space and budget, two four-electrode kickers are set in the lateral feedback system. When the beam oscillation mainly comes from the horizontal direction, both four-electrode kickers are configured for horizontal excitation; when the beam oscillation mainly comes from the vertical direction, both four-electrode kickers are configured for vertical excitation.

[0031] Specifically, solution C saves vertical installation space while reducing the number of kickers and power amplifiers, making it particularly suitable for cost- and space-constrained scenarios such as small synchrotron radiation light sources.

[0032] The advantages and beneficial effects of this invention compared to the prior art are:

[0033] 1. Saves space and cost: Using a single four-electrode device can achieve feedback functions in two orthogonal directions, which greatly saves the longitudinal installation space and equipment cost of the accelerator compared to installing two sets of dual-electrode devices.

[0034] 2. Avoid coupling interference: By using specific phase combinations, the excitation direction is made to be only a single horizontal or vertical direction, which fundamentally eliminates electromagnetic field coupling between the two directions and improves the purity and accuracy of the feedback.

[0035] 3. Flexible application and strong adaptability: The excitation direction can be quickly switched electronically according to the beam dynamics characteristics of different operating stages of the accelerator. For example, if the main oscillation is in the X direction during injection, the device can be switched to X mode; if the main oscillation is in the Y direction during light storage, the device can be switched to Y mode. For some miniaturized, low-cost synchrotron radiation sources, one device of this invention can even replace multiple traditional devices, further reducing construction and maintenance costs.

[0036] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of a transverse feedback system with switchable excitation direction according to an embodiment of the present invention;

[0038] Figure 2 This is a schematic diagram of a traditional two-electrode Kicker model and its vertical installation in an embodiment of the present invention;

[0039] Figure 3 This is a schematic diagram of the four-electrode Kicker model and its 45° installation in an embodiment of the present invention;

[0040] Figure 4 This is an electromagnetic field distribution diagram in the vertical mode of an embodiment of the present invention;

[0041] Figure 5 This is a flowchart of a control method for a lateral feedback system with switchable excitation direction, as described in an embodiment of the present invention. Detailed Implementation

[0042] In the description of this invention, it should be noted that the terms "upper," "lower," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product is in use. They are used only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," and "connect" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0043] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0044] like Figure 1 As shown, the present invention provides a lateral feedback system with switchable excitation direction, comprising:

[0045] The beam position detector (BPM) is used to measure the beam oscillation signal and transmit it to the RF front end.

[0046] The RF front end is electrically connected to the beam position detector (BPM) and is used to receive the beam signal sent by the BPM, amplify and filter it, and then send it to the ADC module.

[0047] The ADC module, electrically connected to the RF front end, is used to convert the beam signal into a digital signal and send it to the digital signal processing module.

[0048] The digital signal processing module, electrically connected to the ADC module, is used to perform digital signal processing calculations, obtain excitation signals, and send them to the DAC module.

[0049] The DAC module, electrically connected to the digital signal processing module, is used to perform digital-to-analog conversion and send the data to the power divider.

[0050] The power divider, electrically connected to the DAC module, is used to adjust the phase of the excitation signal and send it to the exciter.

[0051] The exciter, comprising a power amplifier, a low-pass filter, four strip electrodes, and a matched load, is used for lateral feedback based on a phase-adjusted analog signal.

[0052] This invention achieves feedback in two orthogonal directions using a single four-electrode setup, significantly saving vertical installation space and equipment costs compared to installing two dual-electrode setups. It is important to note that the excitation direction switching in this invention is achieved through a soft switching method using software and electronics.

[0053] In some embodiments of this application, both the beam position detector (BPM) and the strip electrode are positioned at points where the β function is large, thereby maximizing the amplitude of the oscillation signal.

[0054] In some embodiments of this application, the matching load is 50Ω and is electrically connected to the upstream port of the four-strip electrode for signal matching; the four-strip electrode includes electrodes composed of four strips A, B, C, and D.

[0055] In some embodiments of this application, the power amplifier and the low-pass filter are used to amplify the power of the phase-adjusted analog signal and filter out high-frequency noise, respectively. The low-pass filter is electrically connected to the downstream ports of the four electrodes.

[0056] In some embodiments of this application, the operating modes of the lateral feedback system include vertical mode and horizontal mode;

[0057] In vertical mode, excitation signals with equal amplitudes and phases of 180°, 180°, 0°, and 0° are applied to A, B, C, and D, respectively. Due to the symmetry of the boundary conditions, the excited electric field is along the vertical direction, and the excited magnetic field surrounds the vertical direction. The cluster near the center experiences a superposition of electric and magnetic forces in the vertical direction, expressed as:

[0058] F = q(E + v × B);

[0059] In horizontal mode, excitation signals with equal amplitude and phases of 0, 180, 180, and 0 are applied to A, B, C, and D respectively. Its working principle is the same as that of vertical mode. The electromagnetic field direction of vertical mode is rotated by 90°, and the excitation of the bundle near the center becomes horizontal.

[0060] In some embodiments of this application, such as Figure 5 As shown, a control method for a transverse feedback system with switchable excitation direction is also disclosed, comprising the following steps:

[0061] S1. Configure a lateral feedback system.

[0062] S2. When the beam disturbance mainly comes from the horizontal direction, the control lateral feedback system operates in horizontal mode to suppress the horizontal oscillation of the beam.

[0063] S3. When the beam disturbance mainly comes from the vertical direction, the control lateral feedback system operates in vertical mode to suppress the vertical oscillation of the beam.

[0064] This invention can rapidly switch the excitation direction using electronic means based on the beam dynamics characteristics of different operating stages of an accelerator. For example, for a synchrotron radiation source accelerator, if the main oscillation is in the X direction during injection, the device switches to X mode; if the main oscillation is in the Y direction during light storage and supply, the device switches to Y mode. For some miniaturized, low-cost synchrotron radiation sources, one device of this invention can even replace multiple traditional devices, further reducing construction and maintenance costs.

[0065] In some embodiments of this application, in S1, the configuration of the lateral feedback system includes:

[0066] a. In the lateral feedback system, two two-electrode kickers and one four-electrode kicker are set up. The two-electrode kickers are used for fixed horizontal or vertical directions, and the four-electrode kickers are selectively excited according to the actual operating mode.

[0067] b. Set up three four-electrode kickers in the lateral feedback system. Each four-electrode kicker can be selectively excited according to the actual operating mode.

[0068] c. Given the limited vertical installation space and budget, two four-electrode kickers are set in the lateral feedback system. When the beam mainly oscillates horizontally, both four-electrode kickers are configured for horizontal excitation; when the beam mainly oscillates vertically, both four-electrode kickers are configured for vertical excitation.

[0069] This invention uses a specific phase combination to ensure that the excitation direction is only a single horizontal or vertical direction, fundamentally eliminating electromagnetic field coupling between the two directions and improving the purity and accuracy of the feedback.

[0070] The system implementation of the present invention will be described in detail below with reference to specific embodiments.

[0071] The four-electrode kicker designed in this invention can replace, for example... Figure 2 The traditional two-electrode kicker shown is mainly suitable for circular vacuum chambers. Electrodes A, B, C, and D are installed at a 45° angle inside the vacuum chamber. If in-phase signals are applied to A and B, while signals to C and D have the same amplitude but opposite signs, then there are equivalent electric boundary conditions on the x-axis and equivalent magnetic boundary conditions on the y-axis. That is, the electric field is perpendicular to the x-axis, and the magnetic field is perpendicular to the y-axis. This is the vertical operating mode, and the electromagnetic field distribution is as follows: Figure 4 As shown (a is the electric field distribution; b is the magnetic field distribution), this is used to suppress vertical instabilities caused by the insert during conventional light supply. Conversely, if signals A and D are in phase, and signals B and C have the same amplitude and phase but are out of phase with A and D, then the equivalent magnetic boundary on the x-axis and the equivalent electric boundary on the y-axis constitute the horizontal operating mode, used to address horizontal instabilities caused by the injected beam. Due to the four-fold symmetry of the Kicker in this invention, there is no substantial difference between the horizontal and vertical operating modes; it is merely equivalent to the Kicker rotating by 90°, and no additional field errors or excitation power reflections caused by mode switching are generated.

[0072] The Kicker designed in this invention is only suitable for circular vacuum chambers of fourth-generation light sources. The Kicker structure is as follows: Figure 3 The four strips are shown. The electrode length is 1 / 4 wavelength corresponding to the high-frequency system frequency. Taking the commonly used 500MHz high-frequency frequency as an example, with a bandwidth of half (250MHz), the electrode length is 300mm. Generally, the larger the electrode angle, the more uniform the excited electromagnetic field, but the influence of the angle on the beam impedance needs to be considered. The two ends of the Kicker strip will adopt a tapered transition structure design, which not only provides better impedance matching but also suppresses the high-frequency components of the beam impedance to a certain extent.

[0073] In this application, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. In case of any inconsistency, the meaning set forth in this specification or derived from the content described herein shall prevail. Furthermore, the terminology used herein is for the purpose of describing embodiments of this application only and is not intended to limit the scope of this application.

[0074] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A directionally switchable transverse feedback system, characterized by, The application relates to a transverse feedback system for a synchrotron radiation light source. The application comprises: a beam position monitor (BPM) for measuring a beam oscillation signal and sending the beam oscillation signal to an RF front end; the RF front end is electrically connected to the beam position monitor (BPM) and is used for receiving the beam oscillation signal sent by the beam position monitor (BPM), amplifying and filtering the beam oscillation signal, and sending the beam oscillation signal to an ADC module; the ADC module is electrically connected to the RF front end and is used for converting the beam oscillation signal into a digital signal and sending the digital signal to a digital signal processing module; the digital signal processing module is electrically connected to the ADC module and is used for performing digital signal processing calculation to obtain an excitation signal and sending the excitation signal to a DAC module; the DAC module is electrically connected to the digital signal processing module and is used for performing digital-to-analog conversion and sending the digital-to-analog converted signal to a power divider; the power divider is electrically connected to the DAC module and is used for adjusting the phase of the signal applied to different strips and sending the signal to an exciter; the exciter comprises a power amplifier, a low-pass filter, four strip electrodes (Kicker) and a matching load and is used for applying transverse feedback excitation to the beam; the working mode of the transverse feedback system comprises a vertical mode and a horizontal mode; in the vertical mode, equal-amplitude excitation signals with phases of 180, 180, 0 and 0 are applied to A, B, C and D, respectively, at this time, due to the symmetry of the boundary condition, the excited electric field is along the vertical direction, the excited magnetic field surrounds the vertical direction, and the beam bunch near the center is subjected to the superposition of the vertical electric field force and the magnetic field force, and the expression is F=q(E+v x b); in the horizontal mode, equal-amplitude excitation signals with phases of 0, 180, 180 and 0 are applied to A, B, C and D, respectively, and the working principle is the same as that of the vertical mode, the electromagnetic field direction of the vertical mode is rotated by 90 degrees, and the excitation of the beam bunch near the center is changed into the horizontal direction.

2. A transversely feedback system having a directionally switchable excitation according to claim 1, characterized in that The beam position monitor (BPM) and the strip electrodes are arranged at a position with a large beta function, so that the amplitude of the oscillation signal reaches the maximum.

3. A transversely feedback system having a directionally switchable excitation according to claim 2, characterized in that The matching load is 50 omega and is electrically connected to the upstream ports of the four strip electrodes and is used for matching the signal; the four strip electrodes comprise electrodes composed of four strip electrodes A, B, C and D.

4. A transversely feedback system having a directionally switchable excitation according to claim 3, characterized in that The power amplifier and the low-pass filter are used for power amplifying the phase-adjusted analog signal and filtering high-frequency noise, respectively, and the low-pass filter is electrically connected to the downstream ports of the four strip electrodes.

5. A control method for exciting a directionally switchable transverse feedback system as claimed in any one of claims 1-4, characterized in that, The application comprises the following steps: S1, configuring a transverse feedback system; S2, when the beam disturbance mainly comes from the horizontal direction, the transverse feedback system is controlled to work in the horizontal mode to suppress the horizontal oscillation of the beam; S3, when the beam disturbance mainly comes from the vertical direction, the transverse feedback system is controlled to work in the vertical mode to suppress the vertical oscillation of the beam.

6. A control method of exciting a directionally switchable transverse feedback system according to claim 5, characterized by In the S1, the configuration mode of the transverse feedback system comprises: a, two two-electrode kickers and one four-strip electrode kicker are arranged in the transverse feedback system, the two two-electrode kickers are respectively used for fixed horizontal or vertical directions, and the four-strip electrode kicker selectively excites according to the actual operation mode; b, three four-strip electrode kickers are arranged in the transverse feedback system, and each four-strip electrode kicker can selectively excite according to the actual operation mode. c. Given the limited vertical installation space and budget, two four-electrode kickers are set in the lateral feedback system. When the beam oscillation mainly comes from the horizontal direction, both four-electrode kickers are configured for horizontal excitation; when the beam oscillation mainly comes from the vertical direction, both four-electrode kickers are configured for vertical excitation.

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