A method and apparatus for automatic loading of large-scale superconducting cavities based on a low-level radio frequency controller

Abstract

This invention provides a method and apparatus for automatic loading of large-scale superconducting cavities based on a low-level radio frequency (RF) controller. The method includes configuring a low-level RF controller for each superconducting cavity, and each RF controller having an embedded processor. Specifically, the method comprises an automatic loading process, a state evaluation process, a parameter snapshot and automatic recovery process, and an anomaly rollback and safety wait process. Therefore, by utilizing the embedded processor within the low-level RF controller, this invention fully localizes the finite state machine logic for automatic loading, real-time monitoring, and automatic recovery, achieving fully unattended loading of the superconducting cavity from RF shutdown to stable closed-loop operation.

Description

Technical Field

[0001] This invention relates to the field of superconducting radio frequency control for particle accelerators, and more specifically to a method and apparatus for automatic loading of a large-scale superconducting cavity based on a low-level radio frequency controller. Background Technology

[0002] During the operation of a linear particle accelerator, the operating state of the superconducting cavity directly affects the stability of the beam and the availability of the accelerator device. A low-level radio frequency (LLRF) control system can precisely control the cavity field amplitude, phase, and resonant frequency of the superconducting cavity. As the scale of linear accelerators continues to expand, rapid and stable loading of the superconducting cavity has become a critical aspect of device startup, operation, and maintenance.

[0003] The loading process of a superconducting cavity typically involves multiple steps, including RF system initialization, open-loop power loading, amplitude closed-loop control, frequency tuning, phase closed-loop control, and operational status confirmation. In actual engineering operations, this process has long relied on manual execution of each cavity individually. Operators need to repeatedly adjust the amplitude, phase, and tuner position based on experience, resulting in low loading efficiency and difficulty in maintaining consistency among different operators, making it difficult to meet the rapid startup requirements of large-scale systems.

[0004] To address the aforementioned issues, existing technologies attempt to automate the superconducting cavity loading process through software. These solutions typically employ a centralized or semi-centralized control architecture, deploying an automatic loading program on the upper-level control system. This program communicates with multiple low-level RF controllers via a control network, managing the loading process of multiple superconducting cavities simultaneously using parallel processes or threads. While these solutions reduce manual intervention to some extent, they still have the following shortcomings in large-scale parallel operation scenarios with superconducting cavities: 1) Loading decisions and execution control are separated at different control nodes, requiring the host computer to issue commands to each controller via the control network. In large-scale parallel operation scenarios with superconducting cavities, in centralized / semi-centralized architectures, the host computer needs to periodically collect the status of multiple cavities and issue control commands. As the number of cavities increases, network latency jitter and congestion on the host computer lead to: 2) delayed status determination, missing the closed-loop establishment window; 3) untimely shutdown / rollback after anomaly triggering, resulting in excessive reflected power or amplified cascading triggers; 4) multi-cavity thread scheduling competition causing command out-of-order or repeated execution, resulting in poor loading consistency.

[0005] In summary, in the operation of large-scale superconducting linear accelerators, there is an urgent need for a technical solution that can automatically load and monitor the operation of superconducting cavities at a low-level radio frequency controller, so that each superconducting cavity can independently complete loading and recovery without relying on the real-time control of the upper-level control network, thereby improving the system's parallel capability, operational determinism, and overall availability. Summary of the Invention

[0006] This invention aims to at least solve one of the technical problems existing in the prior art. Therefore, in response to the above-mentioned problems, the purpose of this invention is to provide a method and apparatus for automatic loading of large-scale superconducting cavities based on a low-level radio frequency controller. By offloading the decision-making and execution logic for automatic loading and operation monitoring of superconducting cavities to the low-level radio frequency controller itself, each superconducting cavity can independently complete loading and automatic recovery without relying on an upper-level control network, significantly improving the parallel operation capability and overall availability of large-scale superconducting cavities.

[0007] To achieve the above-mentioned objectives, the technical solution adopted by this invention is as follows: In a first aspect, the present invention provides a method for automatic loading of a large-scale superconducting cavity based on a low-level radio frequency controller, comprising: Each superconducting cavity is equipped with a corresponding low-level radio frequency controller, and each low-level radio frequency controller contains an embedded processor. Each embedded processor runs an independent control program, specifically: Automatic loading process: The automatic loading process of the superconducting cavity is implemented in the form of a finite state machine on the low-level RF controller, including system initialization and state reset, open-loop power loading, amplitude closed-loop establishment, frequency tuning, closed-loop power adjustment, phase closed-loop establishment, and operation monitoring. Status assessment process: The low-level radio frequency controller collects signals related to the operating status of the superconducting cavity in real time to perform real-time status assessment. Parameter snapshot and automatic recovery process: In the predetermined automatic loading critical state, the low-level RF controller saves the operating parameters on a snapshot. When an abnormality occurs and the safety conditions are met, the snapshot is called to fill in the parameters and re-trigger the loading process to achieve stable automatic recovery. Abnormal rollback and safety wait process: When an abnormality is detected, the low-level RF controller shuts down the RF drive and enters a safety wait state. When the operating conditions are restored, it will automatically reload or continue to wait and report the abnormality.

[0008] In some possible implementations, the low-level radio frequency controller locally acquires signals related to the operating status of the superconducting cavity in real time, including cavity field amplitude signals, cavity field phase signals, frequency or frequency-related status signals, interlocking and safety status signals. All of the above signals are directly acquired by the low-level radio frequency controller and participate in the status determination.

[0009] In some possible implementations, the system initialization and state reset operations are performed as follows: Set the RF drive output and set value to zero; Close the amplitude closed loop, phase closed loop, and frequency tuning related control loops; Reset the control parameters and status flags related to the auto-loading process, and set them to self-excited mode; The finite state machine detects the current vacuum state and interlocking state of the superconducting cavity. When both the vacuum state and the interlocking state meet the preset safety conditions, the finite state machine allows the entry into open-loop power loading. When the safety conditions are not met, the finite state machine remains in the current state or switches to a safety waiting state.

[0010] In some possible implementations, the open-loop power loading operation is as follows: The low-level RF controller is based on the target cavity pressure. and current chamber pressure The deviation between the values ​​is adjusted by setting different drive output values ​​based on different thresholds, gradually increasing the RF drive output to ensure the smooth establishment of the superconducting cavity electric field. In this state, the low-level RF controller monitors the changes in the cavity field amplitude in real time. When the cavity field amplitude reaches the preset loading condition and remains stable, the finite state machine switches to amplitude closed-loop establishment. When a vacuum abnormality, interlock trigger, or cavity field abnormality is detected during the loading process, the finite state machine immediately triggers abnormal backoff processing.

[0011] In some possible implementations, the operation performed to establish the amplitude closed loop is as follows: The current amplitude error is read. When the amplitude error is greater than the set threshold, the cavity field amplitude is gradually converged to the target range by adjusting the amplitude setting value. When the cavity field amplitude deviation is less than the preset threshold and remains stable, the closed loop is opened and the effective state machine switches to frequency tuning. During the amplitude closed loop establishment process, if an abnormal operation or safety status change is detected, the effective state machine performs abnormal rollback processing.

[0012] In some possible implementations, frequency tuning performs the following operations: The low-level RF controller calculates the difference between the frequency and the target frequency in real time and defines this difference as the detuning of the cavity. When the absolute value of the detuning is greater than the frequency threshold, frequency adjustment is initiated. During this process, the low-level RF controller continuously evaluates the tuning effect. When it detects that multiple consecutive tuning operations have caused the frequency deviation to not decrease or even increase, it automatically adjusts the tuning control strategy to restore the effectiveness of the tuning process. When the frequency-related indicators meet the preset stability criteria, the finite state machine switches to closed-loop power regulation.

[0013] In some possible implementations, the closed-loop power regulation performs the following operations: In amplitude closed-loop control mode, the low-level RF controller performs power regulation. Specifically, it gradually adjusts the set value of the cavity pressure amplitude based on the target cavity pressure. The low-level RF controller compares the deviation between the current cavity pressure and the target cavity pressure in real time and dynamically adjusts the amplitude set value according to the sign of the deviation. When the current cavity pressure is less than the target cavity pressure (negative deviation), the low-level RF controller increases the set value in a certain step to increase the amplitude of the electric field inside the cavity. When the current cavity pressure is greater than the target cavity pressure (positive deviation), the low-level RF controller gradually decreases the set value. Through the above adjustment, when the absolute value of the cavity pressure deviation is less than the preset power threshold, the finite state machine switches to phase closed-loop establishment.

[0014] In some possible implementations, the operation performed to establish the phase closed loop is as follows: The low-level RF controller enables the phase closed-loop control loop locally, and the low-level RF controller locally acquires the current cavity field phase in real time. And calculate its phase with the target. The phase error is updated based on the phase error until the absolute value of the phase error is less than the preset phase closed-loop threshold. When this state remains stable for N consecutive sampling periods, the low-level RF controller determines that the phase closed loop is established, the superconducting cavity automatic loading process ends, and the effective state machine switches to operation monitoring.

[0015] In some possible implementations, the operations performed by the monitoring process are as follows: The superconducting cavity is in a fully closed-loop stable operating state in terms of amplitude, phase, and frequency. The low-level RF controller continuously monitors the cavity field amplitude, phase, set value, and system interlock signal. When the deviation of the above operating parameters is less than the preset threshold, the system maintains the RF Ready state. When the low-level RF controller detects a safety interlock trigger, excessive operating parameters, or other abnormal events that cause the system to stop suddenly, the low-level RF controller immediately forces the RF drive output and set value to zero, cuts off the RF switch, and closes the amplitude, phase, and frequency control loops to enter the safety protection state. When the abnormal condition is detected to be resolved and the preset safety criteria are met, the low-level RF controller automatically triggers a reset operation and restarts the automatic loading process to attempt to restore the normal operation of the superconducting cavity. If the automatic recovery fails within a preset number of attempts, it remains in a safe waiting state and reports the abnormal information, waiting for manual intervention.

[0016] Secondly, the present invention also provides a large-scale superconducting cavity autoloading device based on a low-level radio frequency controller. Each superconducting cavity is equipped with a corresponding low-level radio frequency controller, and each low-level radio frequency controller has an embedded processor inside. Each embedded processor executes a computer program for autoloading, state evaluation, and anomaly recovery logic. When the computer program is executed, it implements any of the methods described above. Because the present invention adopts the above technical solution, it has the following characteristics: 1. This invention adopts a decentralized distributed architecture, configuring an independent low-level radio frequency controller for each superconducting cavity. By sinking the decision logic of automatic loading, real-time monitoring and fault recovery to the embedded processor of the controller, and running an independent program (such as EPICS IOC) on it, the automatic loading, operation monitoring and abnormal handling and recovery logic is implemented in closed loop execution by a finite state machine on the local machine. The upper-level control system is only used for parameter configuration, status display and data recording and does not participate in real-time control decision-making.

[0017] 2. This invention, based on real-time acquisition of cavity field amplitude, phase, frequency, and safety interlock signals by the controller, sequentially completes initialization, open-loop power / amplitude establishment, amplitude closed-loop establishment, frequency tuning and closed-loop establishment, phase closed-loop establishment, and full closed-loop operation monitoring. State assessment and switching are achieved through multiple index thresholds and stability criteria. To improve the determinism of anomaly recovery, snapshots of parameters such as drive values, setpoints, and frequency adjustments are saved at predetermined critical stages. In case of anomalies, RF shutdown and safety waiting are executed, and the snapshots are automatically refilled and the loading process restarted after safety conditions are restored. If automatic recovery fails after a preset number of attempts, protection is maintained and a report is submitted. This enables parallel independent loading and anomaly isolation of multiple superconducting cavities, reducing dependence on upper-level control network latency and scheduling load, improving the parallel capability, operational determinism, and overall availability of large-scale superconducting linear accelerator systems, and meeting the unattended operation requirements of devices with tens to hundreds of cavities. 3. This invention, by utilizing the embedded processor within the low-level radio frequency controller, fully localizes the state machine logic for automatic loading, real-time monitoring, and automatic recovery, enabling unattended loading of the superconducting cavity from radio frequency shutdown to stable operation in a fully closed loop. Even when the upper-level control network is unavailable or experiences time delay jitter, the system can still complete key closed-loop control and state switching locally on the controller. The upper-level control system is used for parameter configuration, status display, and data recording, without needing to participate in the judgment and decision-making of the loading process in real time, significantly improving the parallel operation capability and overall availability of large-scale superconducting cavities.

[0018] In summary, this invention can be widely applied to superconducting radio frequency control in particle accelerators. Attached Figure Description

[0019] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts. In the drawings: Figure 1 This is a schematic diagram of the overall system architecture according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the internal structure of a single-cavity LLRF controller according to an embodiment of the present invention; Figure 3 This is a flowchart of the automatic loading and recovery state machine according to an embodiment of the present invention; Figure 4 This is a schematic diagram of the upper-layer monitoring interface according to an embodiment of the present invention. Detailed Implementation

[0020] It should be understood that the terminology used herein is for the purpose of describing particular exemplary embodiments only and is not intended to be limiting. Unless the context clearly indicates otherwise, the singular forms “a,” “an,” and “described” as used herein may also include the plural forms. The terms “comprising,” “including,” “containing,” and “having” are inclusive and therefore indicate the presence of the stated features, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, elements, components, and / or combinations thereof. The method steps, processes, and operations described herein are not construed as requiring them to be performed in a particular order described or illustrated unless the order of performance is explicitly indicated. It should also be understood that additional or alternative steps may be used.

[0021] Although terms such as first, second, third, etc., may be used in this document to describe multiple elements, components, regions, layers, and / or segments, these elements, components, regions, layers, and / or segments should not be limited by these terms. These terms may be used only to distinguish one element, component, region, layer, or segment from another. Unless the context clearly indicates otherwise, terms such as "first," "second," and other numerical terms used herein do not imply order or sequence. Therefore, the first element, component, region, layer, or segment discussed below may be referred to as the second element, component, region, layer, or segment without departing from the teachings of the exemplary embodiments.

[0022] For ease of description, spatial relative terms may be used in the text to describe the relationship of one element or feature relative to another element or feature as shown in the figure. These relative terms include, for example, "inside," "outside," "middle," "outer," "below," "above," etc. Such spatial relative terms are intended to include different orientations of the device in use or operation, other than those depicted in the figure.

[0023] The present invention provides a method and apparatus for automatic loading of large-scale superconducting cavities based on a low-level radio frequency controller. The method includes configuring a low-level radio frequency controller for each superconducting cavity, and each low-level radio frequency controller having an embedded processor. Each embedded processor runs an independent control program, specifically: Automatic loading process: The automatic loading process of the superconducting cavity is implemented on the low-level radio frequency controller in the form of a finite state machine, including system initialization and state reset, open-loop power loading, amplitude closed-loop establishment, frequency tuning, closed-loop power adjustment, phase closed-loop establishment, and operation monitoring; State evaluation process: The low-level radio frequency controller collects signals related to the operating state of the superconducting cavity in real time for real-time state evaluation; Parameter snapshot and automatic recovery process: In predetermined automatic loading critical states, the low-level radio frequency controller saves snapshots of operating parameters. When an anomaly occurs and safety conditions are met, the snapshot is called to refill the parameters and re-trigger the loading process, achieving stable automatic recovery; Anomaly rollback and safety waiting process: When an anomaly is detected, the low-level radio frequency controller shuts down the radio frequency drive and enters a safety waiting state. When operating conditions recover, it automatically reloads or continues to wait and reports the anomaly. Therefore, this invention utilizes the embedded processor within the low-level radio frequency controller to fully localize the finite state machine logic of automatic loading, real-time monitoring, and automatic recovery, thereby achieving unattended loading of the superconducting cavity from radio frequency shutdown to stable operation in a fully closed loop.

[0024] Exemplary embodiments of the invention will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the invention are shown in the drawings, it should be understood that the invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the invention and to fully convey the scope of the invention to those skilled in the art.

[0025] Example 1: The large-scale superconducting cavity automatic loading method based on a low-level radio frequency controller provided by the present invention includes: S1. Set up the system architecture.

[0026] In this embodiment, a decentralized distributed architecture is adopted, with each superconducting cavity equipped with a digital low-level radio frequency controller. Each low-level radio frequency controller is equipped with an embedded processor (ARM), on which an independent program, such as an EPICS IOC instance, runs. The automatic loading, operation monitoring, and anomaly recovery logic of the superconducting cavity are all executed locally on the low-level radio frequency controller in the form of a finite state machine. The state transitions of this finite state machine do not depend on the participation of the upper-level control system. The upper-level control system is only responsible for parameter configuration, status display, and data recording, and does not participate in real-time control decisions.

[0027] S2, Automatic Loading Process.

[0028] In this embodiment, the automatic loading process is executed by the low-level RF controller itself, including: system initialization and state reset, open-loop power loading, amplitude closed-loop establishment, frequency tuning, closed-loop power adjustment, phase closed-loop establishment and operation monitoring. The entry and exit conditions of each state are determined by the low-level RF controller itself based on the real-time acquired cavity field amplitude, phase, frequency and safety status signals.

[0029] S3, Status Assessment Process.

[0030] In this embodiment, the low-level RF controller performs real-time evaluation based on indicators such as cavity field amplitude deviation, phase deviation, frequency deviation, and interlock / vacuum status. It can enter the next state only after the preset criteria are met, and maintain or back off if the criteria are not met.

[0031] S4, Parameter Snapshot and Automatic Recovery Process.

[0032] In this embodiment, to ensure the determinism of the anomaly recovery process, key state nodes in the automatic loading process are predefined. These key state nodes refer to states where control parameters undergo substantial changes during automatic loading or serve as the starting point for subsequent closed-loop control. They include at least the open-loop power loading completion state, the amplitude closed-loop establishment completion state, and the frequency tuning completion state. When the state machine enters and stabilizes at any key state node, the low-level RF controller saves a snapshot of the current operating parameters, which include at least the amplitude drive value, amplitude setpoint, phase setpoint, and frequency adjustment bias. When an anomaly occurs during loading and is determined to meet preset safety conditions, the controller recalls the most recently saved snapshot to backfill the parameters and re-triggers the loading process based on the backfilled parameter state, thereby achieving deterministic automatic recovery.

[0033] S5, Abnormal Rollback and Safety Waiting Process.

[0034] In this embodiment, when an anomaly is detected, the low-level RF controller locally shuts down the RF drive and enters a safe waiting state; when the operating conditions are restored, it automatically reloads, or continues to wait and reports the anomaly.

[0035] The application of the large-scale superconducting cavity autoloading method based on a low-level radio frequency controller of the present invention will be described in detail below through specific embodiments.

[0036] Example 1: This example uses a single superconducting cavity as the controlled object to illustrate the automatic loading, operation monitoring, and automatic anomaly recovery methods of the superconducting cavity executed on the low-level radio frequency controller of this invention. This example is only used to illustrate the technical concept and control flow of this invention and does not limit the specific hardware model, algorithm form, or parameter values.

[0037] I. System Composition and Operating Environment.

[0038] In this embodiment, as Figure 1 As shown, each superconducting cavity is equipped with a corresponding low-level radio frequency controller. The low-level radio frequency controller has an embedded processor inside, which runs an independent control program to perform functions such as automatic loading state machine, operation monitoring, anomaly handling, parameter snapshot and backfilling for the superconducting cavity.

[0039] Furthermore, the low-level radio frequency controller locally acquires signals related to the operating status of the superconducting cavity in real time, including but not limited to: cavity field amplitude signal, cavity field phase signal, frequency or frequency-related status signal, interlocking and safety status signal. All of the above signals are directly acquired by the low-level radio frequency controller and participate in the status determination; the upper-level control system does not participate in the real-time judgment and control decision of the above signals.

[0040] II. Specific implementation of each state.

[0041] In this embodiment, as Figure 2 , Figure 3 As shown, the automatic loading process of the superconducting cavity is implemented natively in the low-level RF controller in the form of a finite state machine, wherein the finite state machine includes at least the following states: S0: System initialization and state reset.

[0042] When the low-level RF controller receives the auto-load start command, the finite state machine first enters the system initialization and state reset state. In this state, the controller performs the following operations: 1) Reset the RF drive output and setpoint to zero; 2) Close the amplitude closed loop, phase closed loop, and frequency tuning related control loops; 3) Reset the control parameters and status flags related to the automatic loading process, and set them to self-excited mode; 4) Detect the current vacuum state and interlocking state of the superconducting cavity; 5) When the vacuum state and interlock state both meet the preset safety conditions, the state machine is allowed to enter the next state, i.e., enter S1; when the safety conditions are not met, the finite state machine remains in the current state or switches to the safety waiting state.

[0043] S1: Open-loop power loading.

[0044] Under open-loop power loading, the low-level RF controller body adjusts according to the target cavity voltage. and current chamber pressure To mitigate the deviation between the threshold values, different drive output values ​​are set according to different thresholds, gradually increasing the RF drive output to ensure a stable establishment of the superconducting cavity electric field. In this state, the low-level RF controller monitors the changes in the cavity field amplitude in real time. When the cavity field amplitude reaches the preset loading condition and remains stable, the finite state machine switches to amplitude closed-loop establishment, i.e., enters S2; if a vacuum abnormality, interlock trigger, or cavity field abnormality is detected during the loading process, the state machine immediately triggers abnormal backoff processing.

[0045] S2: Amplitude closed loop establishment.

[0046] The current amplitude error is read. When the amplitude error exceeds the set threshold, the cavity field amplitude is gradually converged to the target range by adjusting the amplitude setpoint. When the cavity field amplitude deviation is less than the preset threshold and remains stable, the closed-loop circuit is opened, and the finite state machine switches to frequency tuning, i.e., enters S3. During the amplitude closed-loop establishment process, if an operational abnormality or change in safety status is detected, the finite state machine performs abnormal rollback processing.

[0047] S3: Frequency tuning.

[0048] The low-level RF controller uses the difference between the frequency calculated in real time and the target frequency ( The difference is defined as the cavity's detuning. When the absolute value of detuning is greater than the frequency threshold, frequency adjustment is initiated. Specifically, frequency adjustment is achieved by controlling a stepper motor to drive the tuner position, thereby changing the intrinsic resonant frequency of the superconducting cavity to approach the operating frequency. The tuning direction is determined by the sign of detuning. When detuning is less than 0, the frequency is increased; when detuning is greater than 0, the frequency is decreased. This gradually brings the superconducting cavity's intrinsic frequency closer to the operating frequency. When detuning is less than the frequency threshold, the frequency closed-loop switch is activated. To avoid misjudgment of direction or tuning deadlock during tuning, the low-level RF controller continuously evaluates the tuning effect. If multiple consecutive tuning operations result in the frequency deviation not decreasing or even increasing, the tuning control strategy is automatically adjusted to restore the effectiveness of the tuning process. When the frequency-related indicators meet the preset stability criteria, the finite state machine switches to closed-loop power adjustment, entering state S4.

[0049] S4: Closed-loop power regulation.

[0050] The low-level RF controller will perform power regulation in amplitude closed-loop control mode, specifically including: based on the target cavity voltage ( Using the target cavity pressure as a reference, the setpoint of the cavity pressure amplitude is gradually adjusted. The controller compares the deviation between the current cavity pressure and the target cavity pressure in real time, and dynamically adjusts the amplitude setpoint according to the sign of the deviation. When the current cavity pressure is less than the target cavity pressure, i.e., the deviation is negative, the low-level RF controller increases the setpoint in a certain step to increase the amplitude of the electric field inside the cavity; when the current cavity pressure is greater than the target cavity pressure, i.e., the deviation is positive, the low-level RF controller gradually decreases the setpoint. Through the above adjustment, when the absolute value of the cavity pressure deviation is less than the preset power threshold, the state machine switches to the phase closed-loop state, i.e., enters S5.

[0051] S5: Phase closed loop established.

[0052] The low-level RF controller enables a phase closed-loop control circuit: the low-level RF controller acquires the current cavity field phase in real time. And calculate its phase with the target. The phase error. In this embodiment, the low-level RF controller updates the phase setpoint based on the phase error until the absolute value of the phase error is less than the preset phase closed-loop threshold, and the state remains stable for N consecutive sampling periods. Then, the low-level RF controller determines that the phase closed loop is established, the superconducting cavity automatic loading process ends, and the finite state machine switches to operation monitoring, i.e., enters S6.

[0053] S6: Operation monitoring.

[0054] The superconducting cavity operates in a fully closed-loop stable state in terms of amplitude, phase, and frequency. The low-level RF controller continuously monitors the cavity field amplitude, phase, setpoint, and system interlock signals. When the deviations of the above operating parameters are all less than the preset thresholds, the system maintains the RF Ready state.

[0055] When the low-level RF controller detects a safety interlock trigger (such as vacuum abnormality, cavity temperature abnormality, etc.), an operating parameter exceeding the limit (such as excessive reflected power), or other abnormal events that cause the system to stop suddenly, the low-level RF controller immediately forces the RF drive output and set value to zero, cuts off the RF switch, and closes the amplitude, phase, and frequency control loops to enter the safety protection state.

[0056] When the abnormal condition is detected to be resolved and the preset safety criteria are met, the low-level RF controller automatically triggers a reset operation and restarts the automatic loading process to attempt to restore the normal operation of the superconducting cavity. If the automatic recovery fails within a preset number of attempts, it remains in a safe waiting state and reports the abnormal information, waiting for manual intervention.

[0057] Example 2: Based on the single-cavity automatic loading and automatic recovery implementation method of Example 1, this example further illustrates the system-level implementation of the present invention in the scenario of parallel operation of large-scale superconducting cavities, so as to clarify the parallel expansion capability and independent operation capability of the present invention under multi-cavity conditions.

[0058] I. System Overall Structure In this embodiment, the multiple superconducting cavities in the large-scale linear accelerator are each equipped with their own independent low-level radio frequency (RF) controller. Each RF controller controls one superconducting cavity, and the control logic of each RF controller is independent of the others.

[0059] Each low-level RF controller has an embedded processor running an independent control program or EPICS IOC instance to execute the autoloading state machine, operational status assessment, and anomaly handling logic for the corresponding superconducting cavity. The low-level RF controllers do not share autoloading state machines or real-time control decision logic; their autoloading, operational monitoring, and anomaly recovery processes are all completed independently by each controller. The upper-level control system is only used for parameter configuration, status display, and operational data recording; it does not participate in real-time judgment, scheduling, or closed-loop control decisions during the multi-cavity autoloading process.

[0060] II. Multi-cavity parallel automatic loading operation mode In this embodiment, when the system needs to perform automatic closed-loop operation on multiple superconducting cavities, the upper control system sends automatic loading start commands to multiple low-level radio frequency controllers to trigger the automatic loading state machine of each controller.

[0061] It should be noted that the start command serves only as a trigger signal for the automatic loading process. The upper-level control system does not participate in the real-time decision-making process of entering each state, establishing a closed loop, adjusting parameters, or handling anomalies during the automatic loading process. The automatic loading process of each superconducting cavity is independently driven by its corresponding low-level radio frequency controller based on real-time acquired parameters such as cavity field amplitude, phase, frequency, and safety interlock status.

[0062] Furthermore, under the condition of multi-cavity parallel operation, different superconducting cavities may be in different operating states at the same time. For example, some superconducting cavities are in an automatic loading state, some superconducting cavities have completed loading and are in a fully closed-loop operation state, and some superconducting cavities may be in a retreat or safe waiting state due to operational abnormalities.

[0063] like Figure 1 As shown, each superconducting cavity and its corresponding low-level radio frequency controller are arranged in parallel in the system, combined with Figure 3 The illustrated autoloading state machine process illustrates that different superconducting cavities are in different operating states at the same time and operate independently of each other. Since the control logic of each superconducting cavity is executed independently on the controller itself, there is no control logic coupling relationship between the different operating states, thus avoiding the state cascading effect problem commonly found in centralized or semi-centralized control architectures.

[0064] III. Cavity-level autonomy and anomaly isolation mechanism.

[0065] In this embodiment, each low-level radio frequency controller is only responsible for the operating status of the superconducting cavity it controls. When an anomaly occurs in a superconducting cavity during loading or operation, its anomaly detection, rollback processing, and automatic recovery process are only executed on the low-level radio frequency controller corresponding to that superconducting cavity. During this process, the anomaly handling operation only applies to the superconducting cavity where the anomaly occurred; the automatic loading or stable operation of other superconducting cavities is unaffected; and the upper-level control system does not need to participate in anomaly identification or recovery decisions. Through the above-mentioned cavity-level autonomy and anomaly isolation mechanism, even if an anomaly occurs in an individual superconducting cavity in a large-scale superconducting cavity array, it will not cause the loading process of other superconducting cavities to be interrupted or the operating status to degrade, significantly improving the overall availability of the accelerator device at the system level.

[0066] IV. Parameter management method under multi-cavity parallel operation.

[0067] In this embodiment, each low-level radio frequency controller locally maintains its own operating parameters, state variables, and parameter snapshot data related to its corresponding superconducting cavity.

[0068] Furthermore, the operating parameters, state variables, and parameter snapshot data include, but are not limited to: automatically loaded amplitude, phase, and frequency control parameters; judgment thresholds and stability criteria for each state; and control parameters related to operation monitoring and anomaly handling. These parameters are stored and managed independently on the low-level RF controller itself, without relying on a centralized database or real-time access from an upper-level control system, thus avoiding delays or conflicts caused by centralized parameter access during multi-cavity parallel operation.

[0069] V. System Expansion Capabilities Description.

[0070] In this embodiment, by adopting a cavity-level autonomous control architecture of "one low-level RF controller per superconducting cavity and one independent control instance," the present invention can naturally support the expansion of the number of superconducting cavities. When the number of superconducting cavities increases, only a corresponding number of low-level RF controllers need to be added and the corresponding control programs deployed to achieve system scaling, without the need for centralized modification, rescheduling, or overall reconstruction of the existing superconducting cavity autoloading logic. This architecture avoids the uncertainties introduced by centralized or semi-centralized control schemes when scaling up the system due to increased control network load, increased scheduling complexity, or single point of failure, and is suitable for superconducting linear accelerator systems with dozens or even hundreds of cavities.

[0071] Example 2: Example 1 above provides a method for automatic loading of large-scale superconducting cavities based on a low-level radio frequency controller. Correspondingly, this example provides an automatic loading device for large-scale superconducting cavities based on a low-level radio frequency controller, including a low-level radio frequency controller configured for each superconducting cavity, and an embedded processor installed inside each low-level radio frequency controller. Each embedded processor executes a computer program for automatic loading, status evaluation, and anomaly recovery logic. The computer program executes the method in Example 1.

[0072] The various embodiments in this specification are described in a progressive manner. Similar or identical parts between embodiments can be referred to interchangeably. Each embodiment focuses on describing the differences from other embodiments. In the description of this specification, the terms "a preferred embodiment," "furthermore," "specifically," "in this embodiment," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the embodiments in this specification. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described can be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0073] 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 the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for automatic loading of a large-scale superconducting cavity based on a low-level radio frequency controller, characterized in that, include: Each superconducting cavity is equipped with a corresponding low-level radio frequency controller, and each low-level radio frequency controller contains an embedded processor. Each embedded processor runs an independent control program, specifically: Automatic loading process: The automatic loading process of the superconducting cavity is implemented in the form of a finite state machine on the low-level RF controller, including system initialization and state reset, open-loop power loading, amplitude closed-loop establishment, frequency tuning, closed-loop power adjustment, phase closed-loop establishment, and operation monitoring. Status assessment process: The low-level radio frequency controller collects signals related to the operating status of the superconducting cavity in real time to perform real-time status assessment. Parameter snapshot and automatic recovery process: In the predetermined automatic loading critical state, the low-level RF controller saves the operating parameters on a snapshot. When an abnormality occurs and the safety conditions are met, the snapshot is called to fill in the parameters and re-trigger the loading process to achieve stable automatic recovery. Abnormal rollback and safety wait process: When an abnormality is detected, the low-level RF controller shuts down the RF drive and enters a safety wait state. When the operating conditions are restored, it will automatically reload or continue to wait and report the abnormality.

2. The method for automatic loading of large-scale superconducting cavities based on a low-level radio frequency controller according to claim 1, characterized in that, The low-level radio frequency controller collects signals related to the operating status of the superconducting cavity in real time, including cavity field amplitude signal, cavity field phase signal, frequency or frequency-related status signal, interlocking and safety status signal. All of the above signals are directly collected by the low-level radio frequency controller and participate in the status determination.

3. The method for automatic loading of large-scale superconducting cavities based on a low-level radio frequency controller according to claim 1, characterized in that, The system initialization and status reset operations are as follows: Set the RF drive output and set value to zero; Close the amplitude closed loop, phase closed loop, and frequency tuning related control loops; Reset the control parameters and status flags related to the auto-loading process, and set them to self-excited mode; The finite state machine detects the current vacuum state and interlocking state of the superconducting cavity. When both the vacuum state and the interlocking state meet the preset safety conditions, the finite state machine allows the entry into open-loop power loading. When the safety conditions are not met, the finite state machine remains in the current state or switches to a safety waiting state.

4. The method for automatic loading of large-scale superconducting cavities based on a low-level radio frequency controller according to claim 3, characterized in that, The operation performed during open-loop power loading is as follows: The low-level RF controller is based on the target cavity pressure. and current chamber pressure The deviation between the values ​​is adjusted by setting different drive output values ​​based on different thresholds, gradually increasing the RF drive output to ensure the smooth establishment of the superconducting cavity electric field. In this state, the low-level RF controller monitors the changes in the cavity field amplitude in real time. When the cavity field amplitude reaches the preset loading condition and remains stable, the finite state machine switches to amplitude closed-loop establishment. When a vacuum abnormality, interlock trigger, or cavity field abnormality is detected during the loading process, the finite state machine immediately triggers abnormal backoff processing.

5. The method for automatic loading of large-scale superconducting cavities based on a low-level radio frequency controller according to claim 4, characterized in that, The operation for establishing the amplitude closed loop is as follows: The current amplitude error is read. When the amplitude error is greater than the set threshold, the cavity field amplitude is gradually converged to the target range by adjusting the amplitude setting value. When the cavity field amplitude deviation is less than the preset threshold and remains stable, the closed loop is opened and the effective state machine switches to frequency tuning. During the amplitude closed loop establishment process, if an abnormal operation or safety status change is detected, the effective state machine performs abnormal rollback processing.

6. The method for automatic loading of large-scale superconducting cavities based on a low-level radio frequency controller according to claim 5, characterized in that, The operation performed by frequency tuning is as follows: The low-level RF controller calculates the difference between the frequency and the target frequency in real time and defines this difference as the detuning of the cavity. When the absolute value of the detuning is greater than the frequency threshold, frequency adjustment is initiated. During this process, the low-level RF controller continuously evaluates the tuning effect. When it detects that multiple consecutive tuning operations have caused the frequency deviation to not decrease or even increase, it automatically adjusts the tuning control strategy to restore the effectiveness of the tuning process. When the frequency-related indicators meet the preset stability criteria, the finite state machine switches to closed-loop power regulation.

7. The method for automatic loading of large-scale superconducting cavities based on a low-level radio frequency controller according to claim 6, characterized in that, The closed-loop power regulation operation is as follows: In amplitude closed-loop control mode, the low-level RF controller performs power regulation. Specifically, it gradually adjusts the set value of the cavity pressure amplitude based on the target cavity pressure. The low-level RF controller compares the deviation between the current cavity pressure and the target cavity pressure in real time and dynamically adjusts the amplitude set value according to the sign of the deviation. When the current cavity pressure is less than the target cavity pressure (negative deviation), the low-level RF controller increases the set value in a certain step to increase the amplitude of the electric field inside the cavity. When the current cavity pressure is greater than the target cavity pressure (positive deviation), the low-level RF controller gradually decreases the set value. Through the above adjustment, when the absolute value of the cavity pressure deviation is less than the preset power threshold, the finite state machine switches to phase closed-loop establishment.

8. The method for automatic loading of large-scale superconducting cavities based on a low-level radio frequency controller according to claim 7, characterized in that, The operation performed to establish a phase closed loop is as follows: The low-level RF controller enables the phase closed-loop control loop locally, and the low-level RF controller locally acquires the current cavity field phase in real time. And calculate its phase with the target. The phase error is updated based on the phase error until the absolute value of the phase error is less than the preset phase closed-loop threshold. When this state remains stable for N consecutive sampling periods, the low-level RF controller determines that the phase closed loop is established, the superconducting cavity automatic loading process ends, and the effective state machine switches to operation monitoring.

9. The method for automatic loading of large-scale superconducting cavities based on a low-level radio frequency controller according to claim 8, characterized in that, The operation performed by the operation monitoring is as follows: The superconducting cavity is in a fully closed-loop stable operating state in terms of amplitude, phase, and frequency. The low-level RF controller continuously monitors the cavity field amplitude, phase, set value, and system interlock signal. When the deviation of the above operating parameters is less than the preset threshold, the system maintains the RF Ready state. When the low-level RF controller detects a safety interlock trigger, excessive operating parameters, or other abnormal events that cause the system to stop suddenly, the low-level RF controller immediately forces the RF drive output and set value to zero, cuts off the RF switch, and closes the amplitude, phase, and frequency control loops to enter the safety protection state. When the abnormal condition is detected to be resolved and the preset safety criteria are met, the low-level RF controller automatically triggers a reset operation and restarts the automatic loading process to attempt to restore the normal operation of the superconducting cavity. If the automatic recovery fails within a preset number of attempts, it remains in a safe waiting state and reports the abnormal information, waiting for manual intervention.

10. A large-scale superconducting cavity automatic loading device based on a low-level radio frequency controller, characterized in that, Each superconducting cavity is equipped with a corresponding low-level radio frequency controller, and each low-level radio frequency controller has an embedded processor inside. Each embedded processor executes a computer program for automatic loading, status evaluation, and anomaly recovery logic. When the computer program is executed, it implements the method described in any one of claims 1 to 9.

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