Accelerator beam arrival time measurement method and apparatus

Abstract

The application provides an accelerator beam arrival time measurement method and device, relates to the technical field of particle accelerator beam measurement, and comprises the following steps: acquiring a reference signal; acquiring a beam radio frequency signal; transmitting the reference signal and the beam radio frequency signal to the same radio frequency transmission and processing link after time division multiplexing, so that the reference signal and the beam radio frequency signal are subjected to consistent link phase interference; the phase drift amount introduced by the link can be accurately determined based on the phase information of the reference signal; phase drift compensation is performed on the second time division multiplexing signal according to the phase drift amount to obtain a third time division multiplexing signal, so that the phase fluctuation introduced by the transmission link can be effectively offset; a radio frequency local oscillator signal is generated based on the same reference signal, beam arrival time calculation is completed according to the third time division multiplexing signal and the radio frequency local oscillator signal, the consistency of the phase reference is ensured, and the measurement precision of the beam arrival time and the long-term operation stability of the system are improved.

Description

Technical Field

[0001] This application relates to the field of particle accelerator beam measurement technology, and more specifically to a method and apparatus for measuring the arrival time of an accelerator beam. Background Technology

[0002] Beam arrival time measurement is one of the core technologies in the field of accelerator beam diagnostics. Its measurement accuracy directly affects the data quality and device control performance in high-energy physics experiments, synchrotron radiation applications, and other scenarios. With the continuous improvement of accelerator device performance, higher requirements are placed on the measurement accuracy of beam arrival time and the long-term stability of the system.

[0003] In related technologies, beam arrival time measurement is mostly based on the principle of radio frequency phase detection. This involves mixing and phase-detecting the radio frequency signal corresponding to the beam with the local oscillator signal, and then calculating the beam arrival time based on the phase difference. However, in practical applications, the signal transmission link is susceptible to phase shifts caused by environmental interference, which can adversely affect the final measurement accuracy and system stability. Summary of the Invention

[0004] In view of this, embodiments of this application provide an accelerator beam arrival time measurement method and apparatus.

[0005] According to a first aspect of this application, an accelerator beam arrival time measurement method is provided, comprising: acquiring a reference signal; acquiring a beam radio frequency (RF) signal; performing time-division multiplexing (TDM) on the reference signal and the beam RF signal to obtain a first TDM multiplexed signal; sending the first TDM multiplexed signal into an RF transmission and processing link to obtain a second TDM multiplexed signal; determining a phase drift amount based on the phase information corresponding to the reference signal in the second TDM multiplexed signal and the reference phase of the reference signal; performing phase drift compensation on the second TDM multiplexed signal based on the phase drift amount to obtain a third TDM multiplexed signal; generating an RF local oscillator signal based on the reference signal; and acquiring the beam arrival time based on the third TDM multiplexed signal and the RF local oscillator signal.

[0006] According to an embodiment of this application, obtaining a reference signal includes: obtaining a first electrical signal; modulating the first electrical signal onto a continuous optical carrier to obtain a first optical signal; transmitting the first optical signal to a receiving end via an optical fiber link to obtain a second optical signal at the receiving end; returning the second optical signal along the original optical fiber link to obtain a third optical signal; comparing the phase of the third optical signal with the first optical signal to obtain a reference drift introduced by the optical fiber link; adjusting and compensating the optical path length of the first optical signal based on the reference drift to obtain a fourth optical signal; and converting the fourth optical signal into an electrical signal to obtain the reference signal.

[0007] According to an embodiment of this application, comparing the phase of the third optical signal with the first optical signal to obtain the reference drift introduced by the optical fiber link includes: comparing the phase of the third optical signal with the first optical signal to obtain the round-trip phase difference between the two signals; dividing the round-trip phase difference by a preset value to obtain the reference drift introduced by the optical fiber link.

[0008] According to an embodiment of this application, adjusting and compensating the optical path of a first optical signal based on a reference drift amount to obtain a fourth optical signal includes: inputting the reference drift amount into a controller to generate a control signal; driving an adjustable fiber delay line through the control signal to adjust the optical path of the first optical signal; and transmitting the first optical signal with adjusted optical path to a receiving end via an optical fiber link to obtain the fourth optical signal.

[0009] According to an embodiment of this application, the accelerator beam arrival time measurement method further includes: monitoring the operating status parameters of a continuous optical carrier, the operating status parameters including phase compensation amount, compensation speed and optical signal round-trip arrival time; comparing the operating status parameters with a preset threshold to obtain a comparison result; and determining whether the beam arrival time is abnormal based on the comparison result.

[0010] According to an embodiment of this application, determining the phase drift amount based on the phase information corresponding to the reference signal in the second time-division multiplexed signal and the reference phase of the reference signal includes: digitally sampling the second time-division multiplexed signal to obtain a sampling sequence; locating the time slot interval corresponding to the reference signal in the sampling sequence and obtaining the phase information of the reference signal within the time slot interval; and calculating the difference between the phase information and the reference phase of the reference signal to obtain the phase drift amount.

[0011] According to an embodiment of this application, the process of compensating for phase drift of the second time-division multiplexed signal based on the phase drift amount to obtain the third time-division multiplexed signal includes: acquiring the phase of the corresponding time slot of the beam radio frequency signal in the second time-division multiplexed signal to obtain the measured phase value of the beam radio frequency signal; subtracting the phase drift amount from the measured phase value of the beam radio frequency signal to obtain the compensated phase value; and using the compensated phase value to perform phase correction on the corresponding time slot of the beam radio frequency signal in the second time-division multiplexed signal to obtain the third time-division multiplexed signal.

[0012] According to embodiments of this application, the phase drift includes phase drift introduced by the radio frequency transmission and processing link and reference signal measurement noise.

[0013] According to an embodiment of this application, obtaining the beam arrival time based on the third time-division multiplexed signal and the radio frequency local oscillator signal includes: performing frequency mixing and down-conversion on the beam radio frequency signal and the radio frequency local oscillator signal in the third time-division multiplexed signal to obtain an intermediate frequency signal; obtaining the phase information of the intermediate frequency signal and calculating the beam arrival time.

[0014] According to a second aspect of this application, an accelerator beam arrival time measurement device is provided, comprising: a reference signal acquisition module for acquiring a reference signal; a beam radio frequency signal acquisition module for acquiring a beam radio frequency signal; a time-division multiplexing module for time-division multiplexing the reference signal and the beam radio frequency signal to obtain a first time-division multiplexed signal; a signal transmission module for sending the first time-division multiplexed signal into a radio frequency transmission and processing link to obtain a second time-division multiplexed signal; a phase drift calculation module for acquiring the phase information of the corresponding time slot of the reference signal in the second time-division multiplexed signal, and calculating the phase drift amount by combining it with the reference phase of the reference signal; a phase compensation module for performing phase drift compensation on the second time-division multiplexed signal according to the phase drift amount to obtain a third time-division multiplexed signal; a radio frequency local oscillator generation module for generating a radio frequency local oscillator signal based on the reference signal; and an arrival time calculation module for determining the beam arrival time according to the third time-division multiplexed signal and the radio frequency local oscillator signal.

[0015] The accelerator beam arrival time measurement method provided in this application has at least the following advantages compared with related technologies: By time-division multiplexing the reference signal and the beam radio frequency signal and then transmitting them through the same radio frequency transmission and processing link, the reference signal and the beam radio frequency signal are subjected to consistent link phase interference, and the phase drift introduced by the link can be accurately determined based on the phase information of the reference signal; the phase drift compensation of the second time-division multiplexed signal based on the phase drift amount is used to obtain the third time-division multiplexed signal, which can effectively cancel the phase fluctuation introduced by the transmission link; at the same time, a radio frequency local oscillator signal is generated based on the same reference signal, and the beam arrival time is calculated based on the third time-division multiplexed signal and the radio frequency local oscillator signal, ensuring the consistency of the phase reference and improving the measurement accuracy of the beam arrival time and the long-term operational stability of the system. Attached Figure Description

[0016] The above-mentioned contents, other objects, features and advantages of this application will become clearer from the following description of embodiments with reference to the accompanying drawings, in which:

[0017] Figure 1 A flowchart illustrating an accelerator beam arrival time measurement method according to an embodiment of this application is shown schematically.

[0018] Figure 2 The diagram illustrates a time-division multiplexing of a beam radio frequency signal and a reference signal according to an embodiment of this application.

[0019] Figure 3 The diagram illustrates the mixing and downconversion process of the beam radio frequency signal and the radio frequency local oscillator signal according to an embodiment of this application.

[0020] Figure 4The diagram schematically illustrates a structural diagram of an accelerator beam arrival time measurement system according to an embodiment of this application.

[0021] Figure 5 The schematic diagram illustrates a schematic of an accelerator beam arrival time measurement system according to an embodiment of this application.

[0022] Figure 6 A flowchart illustrating online monitoring and diagnosis of beam arrival time according to an embodiment of this application is shown.

[0023] Figure 7 The diagram illustrates a comparison of the drift results of the output signal amplitude between the conventional scheme and the synchronization scheme of this application according to embodiments of the present application. Detailed Implementation

[0024] The embodiments of this application will now be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of this application. In the following detailed description, numerous specific details are set forth to provide a thorough understanding of the embodiments of this application for ease of explanation. However, it will be apparent that one or more embodiments may be implemented without these specific details. Furthermore, descriptions of well-known structures and technologies are omitted in the following description to avoid unnecessarily obscuring the concepts of this application.

[0025] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of this application. The terms “comprising,” “including,” etc., as used herein indicate the presence of the stated features, steps, operations, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, or components.

[0026] All terms used herein (including technical and scientific terms) have the meanings commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used herein are to be interpreted in a manner consistent with the context of this specification, and not in an idealized or overly rigid way.

[0027] In the field of precision measurement of quantum material properties, particle accelerators can generate highly stable and coherent terahertz (THz) light sources, which are crucial for accurate characterization of quantum material properties. Beam arrival time is one of the key parameters for achieving beam feedback control in particle accelerators, typically requiring a measurement resolution on the order of hundreds of femtoseconds or even higher. Among related technologies, high-resolution beam arrival time measurement methods mainly include electro-optic methods and radio frequency phase-cavity methods. The electro-optic method modulates the transient electrical signal of the beam sensed by a broadband radio frequency probe with a reference laser pulse phase-locked to the accelerator's master clock, and then inverts the beam arrival time by analyzing the modulated laser signal. This method theoretically offers high resolution, but the system structure is complex, debugging and maintenance are difficult, and the system cost and operational complexity are high.

[0028] The radio frequency (RF) phase cavity method directly couples a narrowband beam RF signal carrying beam arrival time information through a cavity beam arrival time monitor (BAM). This signal is then mixed with a local oscillator (LO) signal generated by a timing system to output an intermediate frequency (IF) signal. The beam arrival time can be obtained from the phase of the IF signal. This system has a relatively simple structure and high engineering reliability. However, both the beam RF signal and the RF oscillator signal are inevitably affected by environmental temperature, humidity changes, and mechanical vibrations during generation, distribution, and transmission through the RF transmission and processing link. This introduces phase drift and phase fluctuations, which directly translate into phase errors in the IF signal, reducing the accuracy of beam arrival time measurement. Therefore, achieving long-term phase stability of the beam RF signal and the RF oscillator signal throughout the entire link without increasing the complexity of constant temperature control conditions is a problem that urgently needs to be solved in high-resolution beam arrival time measurement systems.

[0029] Figure 1 This is a flowchart of an accelerator beam arrival time measurement method according to an embodiment of this application.

[0030] like Figure 1 As shown in the figure, this application provides a method for measuring the arrival time of an accelerator beam, characterized in that it includes:

[0031] Step S1: Obtain the reference signal;

[0032] Step S2: Acquire the beam radio frequency signal;

[0033] Step S3: Time-division multiplex the reference signal and the beam radio frequency signal to obtain the first time-division multiplexed signal;

[0034] Step S4: The first time-division multiplexed signal is sent into the radio frequency transmission and processing link to obtain the second time-division multiplexed signal;

[0035] Step S5: Determine the phase drift amount based on the phase information corresponding to the reference signal in the second time-division multiplexed signal and the reference phase of the reference signal;

[0036] Step S6: Perform phase drift compensation on the second time-division multiplexed signal according to the phase drift amount to obtain the third time-division multiplexed signal;

[0037] Step S7: Generate an RF local oscillator signal based on the reference signal;

[0038] Step S8: Obtain the beam arrival time based on the third time-division multiplexed signal and the radio frequency local oscillator signal.

[0039] This application provides a method for measuring the time of arrival (TOA) of an accelerator beam. First, a reference signal and a beam radio frequency (RF) signal are acquired. These are then time-division multiplexed to obtain a first time-division multiplexed signal. This first time-division multiplexed signal is then transmitted and processed through an RF transmission and processing link to obtain a second time-division multiplexed signal. Subsequently, based on the phase information corresponding to the reference signal in the second time-division multiplexed signal and the reference phase of the reference signal, the phase drift introduced by the link is determined. Phase drift compensation is then performed on the second time-division multiplexed signal based on the phase drift, resulting in a third time-division multiplexed signal. Simultaneously, an RF local oscillator signal is generated based on the reference signal. Finally, the beam arrival time is obtained based on the third time-division multiplexed signal and the RF local oscillator signal. This method, by enabling the reference signal and beam RF signal to be transmitted through a shared link using time-division multiplexing, subjectes them to consistent link phase interference. It can accurately determine and compensate for link phase drift based on the phase change of the reference signal. Furthermore, generating the RF local oscillator signal used for measurement using the reference signal ensures the consistency of the phase reference, effectively offsetting phase fluctuations caused by transmission link environmental interference, and improving the measurement accuracy of the beam arrival time and the long-term operational stability of the system.

[0040] Figure 2 This is a time-division multiplexing diagram of the beam radio frequency signal and the reference signal according to an embodiment of this application. The diagram shows the timing distribution relationship of the two types of signals alternatingly passing through the same link in different time slots. In this application, the abbreviation REF refers to the reference signal, RF refers to the beam radio frequency signal, and RF+REF refers to the first time-division multiplexed signal.

[0041] like Figure 2As shown, in some embodiments, time-division multiplexing of the reference signal and the beam RF signal is achieved through timing switching of a microwave switch. The two signals sequentially pass through the same RF transmission and processing link in different time slots, ensuring that both types of signals experience completely identical RF link responses and device drift during transmission and processing, providing a common basis for subsequent link phase drift calibration. A microwave switch is a controller used to switch the RF signal transmission path. In this application, timing control switches the input paths of the reference signal and the beam RF signal, allowing the two types of signals to sequentially enter the same RF transmission and processing link in different time slots. This is the core hardware for achieving time-division multiplexing.

[0042] In some embodiments, the beam radio frequency signal is obtained by coupling the accelerator beam using a cavity beam arrival time probe, and the signal phase corresponds to the arrival time of the beam. The cavity beam arrival time probe is a detection component installed on the accelerator beam channel. When a bundle of charged particles passes through the resonant cavity of the probe, a radio frequency signal is induced through electromagnetic field coupling. The signal phase corresponds one-to-one with the arrival time of the bundle, thereby obtaining the beam radio frequency signal.

[0043] In some embodiments, the RF local oscillator generation module uses a phase-stable reference signal as its common reference and generates an RF local oscillator signal of the corresponding frequency through a frequency synthesis circuit, ensuring that the phase stability of the local oscillator signal is consistent with the reference. The RF local oscillator generation module is a functional unit used to generate the local oscillator signal required for measurement. Using a phase-stable reference signal as the reference source, it outputs an RF local oscillator signal with controlled frequency and phase, providing a unified phase reference for subsequent mixing and downconversion. The frequency synthesis circuit is the core circuit of the RF local oscillator generation module. Using the reference signal as the input clock, it generates an RF local oscillator signal of the specified frequency through a phase-locked loop, frequency multiplication, frequency division, etc., ensuring that the output signal maintains strict phase synchronization with the reference signal.

[0044] In this embodiment, step S1, obtaining the reference signal, includes: obtaining a first electrical signal; modulating the first electrical signal onto a continuous optical carrier to obtain a first optical signal; transmitting the first optical signal to a receiving end via an optical fiber link to obtain a second optical signal at the receiving end; returning the second optical signal along the original optical fiber link to obtain a third optical signal; comparing the phase of the third optical signal with the first optical signal to obtain the reference drift introduced by the optical fiber link; adjusting and compensating the optical path length of the first optical signal based on the reference drift to obtain a fourth optical signal; and converting the fourth optical signal into an electrical signal to obtain the reference signal.

[0045] In some embodiments, the first electrical signal is generated by the master oscillator and is a frequency-stable reference radio frequency signal, serving as the initial phase reference source for the entire measurement system.

[0046] In some embodiments, the first electrical signal is modulated onto a continuous optical carrier by an electro-optic modulator, carrying the phase information of the electrical signal into the optical signal, and transmitted over long distances in the form of an optical signal through an optical fiber link, which can reduce the impact of electromagnetic interference during transmission.

[0047] In some embodiments, the receiver can be configured as a dual synchronous receiver, one of which outputs a reference signal for time-division multiplexing and phase drift calibration with the beam RF signal, and the other outputs a reference signal for generating an RF local oscillator signal; the two receivers use the same phase compensation mechanism to ensure the phase consistency of the output reference signal.

[0048] In some embodiments, the adjustable fiber delay line compensates for the phase drift introduced by the fiber optic link in real time by changing the transmission optical path length of the first optical signal, so that the output fourth optical signal remains phase stable.

[0049] In this embodiment, comparing the phase of the third optical signal with the first optical signal to obtain the reference drift introduced by the optical fiber link includes: comparing the phase of the third optical signal with the first optical signal to obtain the round-trip phase difference between the two signals; dividing the round-trip phase difference by a preset value to obtain the reference drift introduced by the optical fiber link.

[0050] In some embodiments, the second optical signal is transmitted back along the original optical fiber link to obtain the third optical signal, the first optical signal becomes the second optical signal and the second optical signal becomes the third optical signal, and the round-trip transmission path is completely consistent. Therefore, the measured round-trip phase difference corresponds to the total phase drift of the two-way optical fiber link. The preset value can be 2. Dividing the round-trip phase difference by 2 will give the reference drift introduced by the single-way optical fiber link. This calculation method can accurately restore the phase offset of a single optical fiber link.

[0051] In this embodiment, adjusting and compensating the optical path of the first optical signal based on the reference drift to obtain the fourth optical signal includes: inputting the reference drift into the controller to generate a control signal; driving an adjustable fiber delay line through the control signal to adjust the optical path of the first optical signal; and transmitting the first optical signal with adjusted optical path to the receiving end via an optical fiber link to obtain the fourth optical signal.

[0052] In some embodiments, the controller may employ a proportional-integral-derivative control algorithm to generate a corresponding adjustment control signal based on the input reference drift. After receiving the control signal, the adjustable fiber delay line changes the optical path by adjusting the equivalent transmission length of the internal fiber, thereby achieving real-time calibration of the phase of the first optical signal. The first optical signal after optical path adjustment is transmitted to the receiving end along the original fiber link, and a fourth optical signal with a stable phase is output.

[0053] In this embodiment, the accelerator beam arrival time measurement method further includes:

[0054] Monitor the operating status parameters of continuous optical carriers, including phase compensation amount, compensation speed, and round-trip time of optical signal;

[0055] The running status parameters are compared with preset thresholds to obtain the comparison results;

[0056] Based on the comparison results, determine whether the beam arrival time is abnormal.

[0057] In some embodiments, the monitoring of operating status parameters is continuous and real-time, and the trend of parameter changes can directly reflect the long-term stability of the fiber optic link and the measurement system. Preset thresholds are pre-defined according to the system's calibrated normal operating range. When the amount or rate of change of the operating status parameters exceeds the preset threshold, it is determined that the system has a link drift anomaly or an abnormal measurement result, which can trigger an early warning in a timely manner, facilitating system maintenance and fault diagnosis. The measurement system refers to the overall hardware and software for beam arrival time measurement, consisting of an RF transmission and processing link, an RF front-end processing module, an analog-to-digital conversion unit, and a digital signal processing unit, used to complete signal transmission, conditioning, sampling, phase extraction, and result calculation.

[0058] In this embodiment, step S5, determining the phase drift amount based on the phase information corresponding to the reference signal in the second time-division multiplexed signal and the reference phase of the reference signal, includes:

[0059] The second time-division multiplexed signal is digitally sampled to obtain a sampling sequence;

[0060] Locate the time slot interval corresponding to the reference signal in the sampling sequence, and obtain the phase information of the reference signal within the time slot interval;

[0061] The phase drift is calculated by subtracting the phase information from the reference phase of the reference signal.

[0062] In some embodiments, the second time-division multiplexed signal can first undergo synchronous radio frequency processing and down-conversion, and then be digitized and sampled by an analog-to-digital converter to obtain a sampling sequence. The synchronous radio frequency processing includes signal conditioning such as amplification and filtering to ensure that the signal amplitude and purity meet the sampling requirements. Down-conversion converts the high-frequency radio frequency signal into an intermediate-frequency signal, reducing the difficulty of subsequent sampling and improving the phase extraction accuracy. In the sampling sequence, a preset time slot synchronization marker is used to locate the time interval corresponding to the reference signal. Within this interval, the phase information of the reference signal is extracted through digital signal processing. The difference between the extracted phase information and the reference phase of the reference signal is calculated, and the difference is the phase drift introduced by the radio frequency transmission and processing link.

[0063] In this embodiment, step S6, performing phase drift compensation on the second time-division multiplexed signal based on the phase drift amount to obtain the third time-division multiplexed signal, includes:

[0064] The phase of the beam radio frequency signal in the corresponding time slot of the second time division multiplexed signal is acquired to obtain the measured phase value of the beam radio frequency signal;

[0065] The phase drift is subtracted from the measured phase value of the beam radio frequency signal to obtain the compensated phase value;

[0066] The phase of the beam radio frequency signal in the second time-division multiplexed signal is corrected by using the compensated phase value to obtain the third time-division multiplexed signal.

[0067] In some embodiments, the time slot interval corresponding to the beam radio frequency signal is first located in the sampling sequence of the second time-division multiplexed signal, and the phase of the signal in the time slot is collected to obtain the measured phase value of the beam radio frequency signal; the measured phase value is subtracted from the previously obtained phase drift to obtain the compensated phase value after eliminating the influence of link drift; the phase of the beam radio frequency signal in the time slot is corrected based on the compensated phase value, and after the correction is completed, the complete time-division multiplexed signal, i.e., the third time-division multiplexed signal, is output.

[0068] In this embodiment, the phase drift includes phase drift introduced by the radio frequency transmission and processing link and reference signal measurement noise.

[0069] In some embodiments, the phase drift introduced by the RF transmission and processing link mainly comes from the temperature drift and time drift of devices such as cables, amplifiers, and filters in the link, as well as the phase disturbance caused by environmental vibration, and is the main component of the drift amount; the reference signal measurement noise comes from the quantization noise and circuit noise in the phase extraction process, and belongs to the error component; since the time interval between the reference signal time slot and the beam RF signal time slot is extremely short, it can be assumed that the link phase drift amount in adjacent time slots is consistent, so the drift amount can be directly used for phase compensation of the beam RF signal.

[0070] Figure 3 This is a diagram illustrating the mixing and downconversion process of the beam radio frequency signal and the radio frequency local oscillator signal according to an embodiment of this application. It shows the complete signal processing link from mixing, filtering, analog-to-digital conversion to phase extraction. In this application, the abbreviation LO refers to the radio frequency local oscillator signal and IF refers to the intermediate frequency signal.

[0071] like Figure 3 As shown, in this embodiment, step S8, obtaining the beam arrival time based on the third time-division multiplexed signal and the radio frequency local oscillator signal, includes:

[0072] The beam radio frequency signal and the radio frequency local oscillator signal in the third time division multiplexed signal are mixed and down-converted to obtain the intermediate frequency signal;

[0073] The phase information of the intermediate frequency signal is obtained, and the beam arrival time is calculated.

[0074] In some embodiments, the mixing and downconversion processing is completed in the RF front-end processing module. The beam RF signal and the RF local oscillator signal in the third time-division multiplexed signal are input into the mixer. The mixed output signal is filtered by a bandpass filter to obtain a clean intermediate frequency (IF) signal. The IF signal is sent to an analog-to-digital converter for digital sampling, and then digital signal processing is performed by a field-programmable gate array (FPGA) to extract the phase information of the IF signal. Finally, based on the linear correspondence between the IF phase and the beam arrival time, combined with the cavity resonant angular frequency and the system fixed phase offset, the final beam arrival time measurement result is calculated.

[0075] The RF front-end processing module is a functional unit responsible for down-conversion and signal conditioning. It mainly includes devices such as mixers, bandpass filters, and intermediate frequency amplifiers. It is used to perform down-conversion of the beam RF signal and the RF local oscillator signal and output an intermediate frequency signal that meets the amplitude and bandwidth requirements.

[0076] The cavity resonant angular frequency is an inherent parameter of the cavity resonant cavity of the cavity beam arrival time probe, which is determined by the cavity structure and size. The change in beam arrival time is linearly converted into the phase change of the beam radio frequency signal, and the ratio between the two is determined by the cavity resonant angular frequency, which is the core parameter for converting the phase difference into a time value.

[0077] The system fixed phase bias is a fixed phase difference introduced by factors such as the inherent delay of the device, the length of the transmission cable, and the difference in the circuit path, and is independent of the arrival time of the beam. This bias can be measured in advance through system calibration and subtracted during the time conversion process to eliminate the inherent error of the system.

[0078] Figure 4 This is a schematic diagram of the accelerator beam arrival time measurement device, showing the composition of each functional module and the relationship between signal flow.

[0079] like Figure 4 As shown, this application provides an accelerator beam arrival time measurement device, including:

[0080] Reference signal acquisition module 1 is used to acquire a reference signal;

[0081] Beam radio frequency signal acquisition module 2 is used to acquire beam radio frequency signals;

[0082] Time division multiplexing module 3 is used to time-division multiplex the reference signal and the beam radio frequency signal to obtain the first time division multiplexed signal;

[0083] Signal transmission module 4 is used to send the first time-division multiplexed signal into the radio frequency transmission and processing link to obtain the second time-division multiplexed signal;

[0084] Phase drift calculation module 5 is used to obtain the phase information of the corresponding time slot of the reference signal in the second time division multiplexing signal, and calculate the phase drift amount by combining it with the reference phase of the reference signal.

[0085] Phase compensation module 6 is used to perform phase drift compensation on the second time-division multiplexed signal according to the phase drift amount to obtain the third time-division multiplexed signal;

[0086] RF local oscillator generation module 7 is used to generate an RF local oscillator signal based on a reference signal;

[0087] Arrival time calculation module 8 is used to determine the beam arrival time based on the third time division multiplexed signal and the radio frequency local oscillator signal.

[0088] In some embodiments, the radio frequency transmission and processing link includes a radio frequency transmission cable, an amplifier, a filter, and a radio frequency front-end processing module to complete long-distance signal transmission and signal conditioning. Temperature drift, time drift, and disturbances such as ambient temperature and mechanical vibration in the link can all introduce additional phase drift, which is an important source of beam arrival time measurement error.

[0089] Figure 5 This is a schematic diagram of an accelerator beam arrival time measurement system. The reference signal transmitter generates the first electrical signal and modulates it onto a continuous optical carrier, adjusting the optical path length based on the reflection return phase detection result. Two synchronous receivers receive and demodulate the optical reference signal transmitted through the fiber optic cable, outputting two phase-consistent reference signals. The frequency synthesis system uses the reference signal as a reference to generate the RF local oscillator signal and the system operating clock. The first time-division multiplexed signal passes through an RF transmission link (only the RF transmission portion of the RF transmission and processing link) to the beam electronics signal processing system. Within the beam electronics signal processing system, it undergoes RF conditioning, frequency down-conversion, digital sampling, and phase calculation, ultimately outputting the beam arrival time measurement result.

[0090] In the specific implementation process, the radio frequency phase cavity method is used to measure the beam arrival time. First, the first electrical signal is modulated onto a continuous optical carrier. Phase drift introduced by the optical link is compensated in real time through round-trip phase detection and active optical path adjustment, resulting in a fourth phase-calibrated optical signal, which is then converted into an electrical signal to obtain a stable reference signal as a time base. Next, the reference signal and the beam radio frequency (RF) signal are time-division multiplexed to obtain a first time-division multiplexed signal. This first time-division multiplexed signal is then sent to the same RF transmission and processing link for transmission and conditioning, resulting in a second time-division multiplexed signal. Based on the phase change of the reference signal in the second time-division multiplexed signal, the phase drift introduced by the link is calculated, and the phase of the beam RF signal in the second time-division multiplexed signal is calibrated and corrected to obtain a third time-division multiplexed signal. On this basis, an RF local oscillator signal is generated from the phase-stable reference signal, and the beam RF signal and the RF local oscillator signal in the third time-division multiplexed signal are mixed and down-converted to obtain an intermediate frequency (IF) signal. Finally, the phase information of the IF signal is processed to calculate the beam arrival time, thereby improving the accuracy of beam arrival time measurement and enabling online monitoring of the measurement system's operating status. The above method mainly includes the following steps:

[0091] First, a reference signal is generated and distributed to compensate for phase drift in the fiber optic transmission link in real time. A first electrical signal is modulated onto a continuous optical carrier to obtain a first optical signal. This first optical signal is transmitted over a long distance via optical fiber to a first synchronous receiver, where a second optical signal is obtained. Fiber optic links are susceptible to time-varying phase drift due to factors such as temperature and vibration. Therefore, the phase of the optical signal obtained after demodulation at the receiving end is: , That is, the reference phase of the demand.

[0092] To compensate for this drift, the system employs a reflection-backhaul detection and active compensation mechanism: the second optical signal is split into a third and a fourth optical signal. The third optical signal is then reflected back to the transmitting end along the original fiber optic link using a Faraday Rotator Mirror (FRM). At the transmitting end, the returned third optical signal is compared with the first optical signal to obtain the round-trip phase difference between the two signals, which is the total phase drift introduced by the two-way fiber optic link. The reference drift is input to the controller, which uses a proportional-integral-derivative (PID) control algorithm to generate a control signal. This signal drives an adjustable fiber delay line (which can be a voltage-controlled fiber delay line) to adjust the transmission optical path of the first optical signal, thus achieving phase closed-loop compensation. After compensation, the phase of the final output fourth optical signal is stabilized at:

[0093] The phase-calibrated fourth optical signal is converted into an electrical signal, thus obtaining a phase-stable reference signal. Simultaneously, the continuous optical carrier transmitted to the second synchronous receiver also undergoes the same phase compensation mechanism to obtain the same phase-stable reference signal; one reference signal is used for time-division multiplexing and phase drift calibration with the beam RF signal, and the other reference signal is used to generate the RF local oscillator signal.

[0094] Secondly, the reference signal and the beam RF signal are time-division multiplexed to calibrate the phase drift of the RF transmission and processing link. The beam RF signal is obtained by coupling from a cavity beam arrival time probe (BAM). After being output from the probe, it is transmitted to the digital acquisition unit through cables, amplifiers, filters, and other devices. This RF transmission and processing link introduces additional phase drift. The main causes are temperature drift and time drift of the device. To eliminate this effect, time-division multiplexing calibration technology is adopted: timing control is performed by microwave switches so that the reference signal and the beam RF signal pass through the same RF transmission and processing link in different time slots. After the two are combined, they form the first time-division multiplexed signal, which is then processed by the link and output as the second time-division multiplexed signal.

[0095] Let the first Within each calibration cycle: in the time slot corresponding to the reference signal, the digitally extracted reference signal phase (i.e., the phase information of the reference signal in the second time-division multiplexed signal) is as follows:

[0096]

[0097] In the time slot corresponding to the adjacent beam RF signal, the extracted beam RF signal phase (i.e., the measured phase value of the beam RF signal) is:

[0098]

[0099] in, Noise is measured using a reference signal. Noise is measured for beam radio frequency signals. The reference phase of the reference signal is an ideal reference phase that has not passed through the RF transmission and processing link and is unaffected by link drift and measurement noise. . This represents the true phase of the beam RF signal within the k-th calibration cycle, carrying only beam arrival time information and without superimposed link drift or measurement noise. The phase drift includes the phase drift introduced by the RF transmission and processing link and the reference signal measurement noise. Due to the extremely short interval between two measurements, the phase drift of the RF transmission and processing link can be considered as... To maintain consistency, the real-time link drift calibration amount (i.e., phase drift amount) can be calculated:

[0100]

[0101] The phase shift is used to compensate the measured phase of the beam radio frequency signal in real time, and the compensated phase value is obtained:

[0102]

[0103] By correcting the phase of the corresponding time slot of the beam RF signal in the second time-division multiplexed signal using the compensated phase value, the third time-division multiplexed signal can be obtained. After compensation, the RF transmission and processing link drift in the phase of the beam RF signal is effectively eliminated, leaving only a small amount of differential measurement noise.

[0104] Then, the mixing downconversion and beam arrival time calculations are performed. The beam radio frequency signal (phase) in the third time-division multiplexed signal is then used. ) and the phase-stable radio frequency local oscillator signal generated by the reference signal (phase) Mixing and downconversion are performed at the RF front end.

[0105] In the measurement system, let the RF signal of the beam coupled from the beam probe and the RF local oscillator signal generated by the reference signal be represented as follows:

[0106]

[0107]

[0108] in, , These are the signal amplitude coefficients, , These are the angular frequencies of the beam radio frequency signal and the radio frequency local oscillator signal, respectively. , The initial phases of the beam RF signal and the RF local oscillator signal are respectively. The intermediate frequency signal obtained after mixing and downconverting the two is expressed as:

[0109]

[0110] in, This is the proportionality coefficient. The charge of the cluster. The decay time constant is the intermediate frequency. Intermediate frequency phase Intermediate frequency phase This reflects information about the beam arrival time. Substitute and set We can obtain:

[0111] Therefore, the beam arrival time is ultimately calculated using the following formula:

[0112]

[0113] in, The system's fixed bias, which includes the inherent offset of the cavity, can be determined through calibration. This is the cavity resonant angular frequency. The phase of the intermediate frequency signal is measured with high precision. This allows for precise measurement of beam arrival time.

[0114] Figure 6 This is a flowchart of online monitoring and diagnosis of beam arrival time according to an embodiment of this application. The execution logic for determining system malfunctions by comparing operating status parameters with preset thresholds is presented.

[0115] Finally, the operating status parameters of the continuous optical carrier are continuously monitored, and anomaly detection and diagnosis are performed based on preset thresholds, specifically as follows: Figure 6 As shown.

[0116] The system continuously monitors two key status parameters during operation: the first is the optical phase compensation amount. Second, the beam arrival time (tar). The long-term trends of these parameters reflect the stability of the corresponding link.

[0117] The system sets the following threshold judgment rules to achieve online monitoring and diagnosis:

[0118] Long-term drift monitoring: Calculating optical phase compensation and phase shift Drift rate over a long period of time (e.g., 1 hour) .like Exceeding the preset threshold (For example, if the corresponding phase change rate exceeds 0.1° / hour), a "link slow drift anomaly" alarm will be triggered.

[0119] Abnormal arrival time result: Real-time monitoring of beam arrival time tar. If it exceeds its conventional theoretical threshold t0, an alert for "abnormal arrival time result" is triggered.

[0120] When any of the above-mentioned judgment rules are triggered, the system can automatically record abnormal data, issue alarms, and further upload the data to the host computer to take corresponding measures. It can also decide whether to suspend beam time measurement or enable the backup channel according to preset strategies, thereby realizing the online health management of the system.

[0121] The two diagnostic processes described above—long-term drift monitoring and abnormal arrival time results—can be executed in parallel or in any order, and their specific timing does not constitute a limitation of this application. Furthermore, after determining whether the system is operating normally or abnormally, relevant parameters can be continuously collected to continue the diagnostic process.

[0122] Figure 7 This is a comparison chart of the drift results of the output signal amplitude under the conventional scheme and the synchronous scheme of this application, according to the embodiments of this application. It demonstrates the effect of this scheme in suppressing phase drift and improving measurement stability. This embodiment, through a combination of optical carrier phase synchronization compensation and electrical signal time-division multiplexing calibration, fundamentally suppresses the phase drift throughout the entire link from the signal source to the acquisition end, significantly improving the long-term accuracy and reliability of beam arrival time measurement. The system structure is relatively simple, has high engineering reliability, and has good practical value.

[0123] This application introduces a reference signal generation and distribution mechanism based on a continuous optical carrier, building upon the traditional RF phase cavity method, to generate and distribute a highly stable reference signal. This reference signal not only generates a precise RF local oscillator signal but also enables real-time calibration of the phase drift of the beam RF signal, thereby improving the resolution of beam arrival time measurement. Furthermore, by providing real-time feedback on measurement results and operating parameters, online monitoring of the system's operating status is achieved.

[0124] Compared with related technologies, this application introduces a phase reference synchronization and compensation mechanism based on continuous optical carriers to generate a phase-stable reference signal, which is then used as a reference to generate a precise RF local oscillator signal. Simultaneously, by time-division multiplexing the reference signal and the beam RF signal, they are transmitted along a shared link to withstand consistent phase interference. Based on the reference signal, the link phase drift is measured in real time, and phase compensation is performed on the beam RF signal. This results in obtaining both a high-precision RF local oscillator signal and a phase-calibrated beam RF signal at the measurement end, significantly improving measurement resolution and long-term stability. Furthermore, this application enables real-time monitoring of the system's operating status. Abnormal changes in phase drift or compensation can be promptly identified, enabling online monitoring and diagnosis of the beam arrival time measurement system. Moreover, thanks to the effective suppression of slow drift by the synchronization compensation and time-division multiplexing calibration mechanism, the system only requires localized temperature control at key electronic nodes or the chassis level to meet long-term stable operation requirements. Compared to traditional methods of temperature and humidity control for long-distance RF cables, this significantly reduces system implementation complexity and maintenance difficulty, demonstrating good engineering practicality and promotional value.

[0125] The flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to various embodiments of this application. In this regard, each block in a flowchart or block diagram may represent a module, segment, or portion of code containing one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions indicated in the blocks may occur in a different order than those indicated in the drawings. For example, two consecutively indicated blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. It should also be noted that each block in a block diagram or flowchart, and combinations of blocks in a block diagram or flowchart, may be implemented using a dedicated hardware-based system that performs the specified function or operation, or using a combination of dedicated hardware and computer instructions.

[0126] Those skilled in the art will understand that the features described in the various embodiments of this application can be combined and / or combined in various ways, even if such combinations or combinations are not explicitly described in this application. In particular, the features described in the various embodiments of this application can be combined and / or combined in various ways without departing from the spirit and teachings of this application. All such combinations and / or combinations fall within the scope of this application.

Claims

1. A method for measuring the arrival time of an accelerator beam, characterized in that, include: Obtain a reference signal; Acquire beam radio frequency signals; The reference signal and the beam radio frequency signal are time-division multiplexed to obtain a first time-division multiplexed signal; The first time-division multiplexed signal is sent into the radio frequency transmission and processing link to obtain the second time-division multiplexed signal; The phase drift is determined based on the phase information corresponding to the reference signal in the second time-division multiplexed signal and the reference phase of the reference signal. The second time-division multiplexed signal is phase-shifted based on the phase shift amount to obtain the third time-division multiplexed signal; A radio frequency local oscillator signal is generated based on the reference signal; The beam arrival time is obtained based on the third time-division multiplexed signal and the radio frequency local oscillator signal.

2. The accelerator beam arrival time measurement method according to claim 1, characterized in that, The acquisition of the reference signal includes: Obtain the first electrical signal; The first electrical signal is modulated onto a continuous optical carrier to obtain the first optical signal; The first optical signal is transmitted to the receiving end through an optical fiber link, and the second optical signal is obtained at the receiving end. The second optical signal is returned along the original optical fiber link to obtain the third optical signal; The third optical signal is compared with the first optical signal in phase to obtain the reference drift introduced by the optical fiber link; The optical path of the first optical signal is adjusted and compensated based on the reference drift to obtain the fourth optical signal; The fourth optical signal is converted into an electrical signal to obtain a reference signal.

3. The accelerator beam arrival time measurement method according to claim 2, characterized in that, The step of comparing the phase of the third optical signal with the first optical signal to obtain the reference drift introduced by the optical fiber link includes: The third optical signal is compared with the first optical signal to obtain the round-trip phase difference between the two signals; Divide the round-trip phase difference by a preset value to obtain the reference drift introduced by the optical fiber link.

4. The accelerator beam arrival time measurement method according to claim 2, characterized in that, The step of adjusting and compensating the optical path length of the first optical signal based on the reference drift amount to obtain the fourth optical signal includes: The reference drift value is input to the controller to generate a control signal; The control signal drives the adjustable fiber delay line to adjust the optical path of the first optical signal; The first optical signal, after optical path adjustment, is transmitted to the receiving end via the optical fiber link to obtain the fourth optical signal.

5. The accelerator beam arrival time measurement method according to any one of claims 2 to 4, characterized in that, Also includes: The operating status parameters of the continuous optical carrier are monitored, including phase compensation amount, compensation speed, and optical signal round-trip time. The operating status parameters are compared with preset thresholds to obtain the comparison results; Based on the comparison results, it is determined whether the beam arrival time is abnormal.

6. The accelerator beam arrival time measurement method according to claim 1, characterized in that, The step of determining the phase drift amount based on the phase information corresponding to the reference signal in the second time-division multiplexed signal and the reference phase of the reference signal includes: The second time-division multiplexed signal is digitally sampled to obtain a sampling sequence; Locate the time slot interval corresponding to the reference signal in the sampling sequence, and obtain the phase information of the reference signal within the time slot interval; The phase drift is calculated by subtracting the phase information from the reference phase of the reference signal.

7. The accelerator beam arrival time measurement method according to claim 1, characterized in that, The step of performing phase drift compensation on the second time-division multiplexed signal based on the phase drift amount to obtain the third time-division multiplexed signal includes: The phase of the beam radio frequency signal in the corresponding time slot of the second time-division multiplexed signal is acquired to obtain the measured phase value of the beam radio frequency signal; Subtract the phase drift from the measured phase value of the beam radio frequency signal to obtain the compensated phase value; The phase of the beam radio frequency signal in the second time-division multiplexed signal is corrected by using the compensated phase value to obtain the third time-division multiplexed signal.

8. The method for measuring the arrival time of an accelerator beam according to any one of claims 1, 6, and 7, characterized in that, The phase drift includes the phase drift introduced by the radio frequency transmission and processing link and the reference signal measurement noise.

9. The accelerator beam arrival time measurement method according to claim 1, characterized in that, The step of obtaining the beam arrival time based on the third time-division multiplexed signal and the radio frequency local oscillator signal includes: The beam radio frequency signal and the radio frequency local oscillator signal in the third time-division multiplexed signal are mixed and down-converted to obtain an intermediate frequency signal; The phase information of the intermediate frequency signal is obtained, and the beam arrival time is calculated.

10. An accelerator beam arrival time measuring device, characterized in that, include: The reference signal acquisition module is used to acquire the reference signal; Beam radio frequency signal acquisition module, used to acquire beam radio frequency signals; A time-division multiplexing module is used to time-division multiplex the reference signal and the beam radio frequency signal to obtain a first time-division multiplexed signal; The signal transmission module is used to send the first time-division multiplexed signal into the radio frequency transmission and processing link to obtain the second time-division multiplexed signal; The phase drift calculation module is used to obtain the phase information of the time slot corresponding to the reference signal in the second time division multiplexed signal, and calculate the phase drift amount by combining the reference phase of the reference signal. The phase compensation module is used to perform phase drift compensation on the second time-division multiplexed signal according to the phase drift amount to obtain the third time-division multiplexed signal; A radio frequency local oscillator generation module is used to generate a radio frequency local oscillator signal based on the reference signal; The arrival time calculation module is used to determine the beam arrival time based on the third time-division multiplexed signal and the radio frequency local oscillator signal.

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