On-line measurement method of beam current information based on the principle of steady-state forward voltage vector relationship

Abstract

The present invention discloses an online beam current information measurement method based on the steady-state forward voltage vector relationship principle, comprising: online measuring the cavity incident signal of the radio frequency cavity P f Get the original forward voltage of the RF cavity V f * ; The original forward voltage V f * Perform calibration and normalization to obtain the forward voltage V f ; The forward voltage V f Scaling is performed to obtain the normalized forward voltage U f ; Based on the normalized forward voltage under no beam and beam conditions U f0 and U f1 , calculate the mean of their steady-state values ​​respectively U F0 and U F1 ; Based on the mean of steady-state values U F0 and U F1 Get the steady-state beam equivalent voltage V B ; Based on the steady-state beam equivalent voltage V B , and obtain the steady-state beam current intensity I B Therefore, the present invention can be completely deployed inside the FPGA chip, and can achieve online real-time measurement of beam information at the sub-microsecond level.

Description

Technical Field

[0001] The present invention relates to an online measurement method, device, equipment and medium for beam information based on the principle of steady-state forward voltage vector relationship, and relates to the field of particle accelerators. Background Art

[0002] In a particle accelerator, the energy gain of a beam passing through a radio frequency cavity is expressed as the acceleration cavity pressure. V acc ,Right now ,in, V c is the RF cavity pressure, For beam current and V c In order to obtain the specified energy gain when the beam passes through the RF cavity, the accurate beam synchronization phase must be known. In order to determine the correct beam synchronization phase, a synchronization phase calibration procedure called "phase sweep" is required before the beam is officially operated. In a real accelerator environment, phase drift caused by operating conditions (such as temperature and humidity) will cause the RF cavity phase to change. As the beam runs for a period of time, the calibrated cavity gradually loses the correct phase, eventually causing the phase to Therefore, in order to compensate for the phase drift, the RF cavity needs to be periodically phase-swept.

[0003] Modern large-scale accelerators usually contain dozens or even thousands of RF cavities, and phase scanning usually consumes a lot of machine running time, which seriously reduces the availability of the machine. In addition, both the phase scanning procedure and normal beam operation require special beam diagnostic instruments to measure beam information online in real time, such as beam position detectors (BPM) and beam current detectors (BCM). However, these precision instruments are expensive and difficult to assemble on all RF cavities. The beam passes through the cavity and interacts with the electromagnetic field in the cavity, absorbing or releasing energy from the cavity, resulting in instantaneous changes in the cavity field, namely the beam loading effect.

[0004] In recent years, advanced foreign laboratories represented by the German Electron Synchrotron Radiation Research Center (DESY) have proposed a new method to calibrate the beam synchronization phase using the transient beam load effect. This method can measure and calibrate the beam synchronization phase without phase scanning, thereby saving machine time. When the superconducting cavity operates in closed-loop mode, the beam load will be partially compensated and corrected by the feedback loop, making it difficult to distinguish the contributions of the beam and the loop to the transient beam load signal. Therefore, DESY's new method usually requires the RF cavity to operate in open-loop mode. However, in heavy ion linear accelerators, open-loop operation of the RF cavity may significantly increase beam losses and even cause beam loss. Furthermore, the DESY method also requires that the RF cavity operate approximately in a resonant state (that is, the frequency of the external RF signal that excites the cavity is f RF The resonance frequency of the cavity itself f 0). First, in actual operation, cavity detuning is usually unavoidable, especially for superconducting cavities. Microphonics effect, Lorentz force detuning, helium pressure fluctuations and many other factors can cause cavity detuning, that is, the cavity is no longer in a resonant state. Second, in the case of strong beam load (common in storage rings), for the sake of RF system operation efficiency, it is necessary to actively detune the superconducting cavity to reduce the cavity reflection power.

[0005] In summary, although the existing method can measure the average beam phase online, it has limitations in terms of operation mode and requires relatively harsh operating conditions, which restricts the possibility of comprehensive promotion and application of this method in the field of particle accelerators. Summary of the invention

[0006] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, in view of the above problems, the purpose of the present invention is to provide a beam current information online measurement method, device, equipment and medium based on the principle of steady-state forward voltage vector relationship, which can realize online real-time measurement of beam current information at the sub-microsecond level.

[0007] In order to achieve the above-mentioned invention object, the technical solution adopted by the present invention is:

[0008] In a first aspect, the present invention provides an online beam current information measurement method based on the steady-state forward voltage vector relationship principle, comprising:

[0009] Online measurement of the cavity incident signal of the RF cavity P f Get the original forward voltage of the RF cavity V f * ;

[0010] The original forward voltage Vf * Perform calibration and normalization to obtain the forward voltage V f ;

[0011] The forward voltage V f Scaling is performed to obtain the normalized forward voltage U f ;

[0012] Normalized forward voltage under no beam and beam conditions U f0 and U f1 , calculate the mean of their steady-state values ​​respectively U F0 and U F1 ;

[0013] Based on the steady-state mean U F0 and U F1 Get the steady-state beam equivalent voltage V B ;

[0014] Based on the steady-state beam equivalent voltage V B , and obtain the steady-state beam current intensity I B and beam synchronization phase .

[0015] In one possible implementation, the forward voltage V f Scaling is performed to obtain the normalized forward voltage U f :

[0016] ;

[0017] in, β is the coupling coefficient.

[0018] In one possible implementation, the normalized forward voltage under both no beam and beam conditions is U f0 and U f1 , calculate the mean of their steady-state values ​​respectively U F0 and U F1 ;

[0019] ;

[0020] In the formula, under the condition of no beam, the time interval is t 1 is the starting time, t 2 is the end time, in the time interval under beam conditions t 3 is the starting time, t 4 is the end time.

[0021] In one possible implementation, based on the steady-state mean U F0 and U F1 Get the steady-state beam equivalent voltage V B :

[0022] .

[0023] In one possible implementation, based on the beam equivalent voltage V B Calculate beam current I B and beam synchronization phase ,include:

[0024] ;

[0025] in, is the geometric factor of the cavity, and the value of G is the current normalized cavity pressure V c The corresponding true cavity pressure value, is the cavity loaded quality factor, is the amplitude of the beam equivalent voltage, is the phase of the equivalent voltage.

[0026] In one possible implementation, the steady-state beam equivalent voltage V B The calculation of is obtained by solving the cavity differential equation, the specific process is:

[0027] Establish the cavity differential equation:

[0028] ;

[0029] in, V c0 and V c1 are the cavity pressures without and with beam, respectively. V c ,Signal V f0 and V f1 are the forward voltages without beam current and with beam current respectively. V f, V b is the beam equivalent voltage, Δ ω 0 and Δ ω 1 is the cavity detuning without beam and with beam, ω 0.5 is the half bandwidth of the cavity, β is the coupling coefficient, j is an imaginary unit;

[0030] Using the normalized forward voltage U f Simplifying the right side of the above differential equation, we get the following formula:

[0031] ;

[0032] When the RF cavity operates in closed-loop mode and the beam load is fully compensated, the cavity pressure V c In the case of beam flow or no beam flow, the values ​​are approximately equal, that is, V c0 ≈ V c1 ,and V c Reaching steady state, that is, d V c / d t ≈0; the cavity detuning remains approximately constant during the beam pulse, i.e., Δ ω 0 ≈ Δ ω 1; Based on the above conditions, if the left side of the equations is equal, the right side should also be equal, that is:

[0033] ;

[0034] Obtain the beam equivalent voltage V b :

[0035] ;

[0036] When the forward voltage reaches a steady state, calculate the forward voltage with and without beam current respectively. U f The steady-state value of U F1 and U F0 , U F1 and U F0 Will no longer change with time, and the vector difference between the two is calculated to obtain:

[0037] ;

[0038] in, V B Beam equivalent voltage V b steady-state value.

[0039] In a second aspect, the present invention further provides an online beam current information measurement device based on the steady-state forward voltage vector relationship principle, the device is implemented based on FPGA, and includes:

[0040] The forward voltage acquisition module is configured to measure the cavity incident signal of the RF cavity online. P f Get the original forward voltage of the RF cavity V f * ;

[0041] The pre-processing module is configured to convert the raw forward voltage V f * Perform calibration and normalization to obtain the forward voltage V f ;

[0042] Standardized modules are configured to convert the forward voltage V f Scaling is performed to obtain the normalized forward voltage U f ;

[0043] The steady-state mean calculation module is configured based on the normalized forward voltage under both no-beam and beam conditions. U f0 and U f1 , calculate the mean of their steady-state values ​​respectively U F0 and U F1 ;

[0044] The vector operation module is configured to be based on the steady-state value mean U F0 and U F1 Get the steady-state beam equivalent voltage V B ;

[0045] The beam information extraction module is configured based on the steady-state beam equivalent voltage V B , and obtain the steady-state beam current intensity I B and beam synchronization phase .

[0046] In a third aspect, the present invention also provides an electronic device, comprising: at least one processor; and a memory communicatively connected to the processor; wherein the memory stores instructions executable by the processor, and the instructions are executed by the processor so that the processor can execute any one of the methods described.

[0047] In a fourth aspect, the present invention further provides a computer-readable storage medium storing one or more programs, wherein the one or more programs include computer instructions, and the computer instructions are used to enable a computer to execute any one of the methods described.

[0048] The present invention adopts the above technical solution, and has the following characteristics:

[0049] 1. A very big advantage of the present invention is that all operation modules do not involve complex algorithms (such as derivative operations and curve fitting, etc.), and all algorithms can be completely deployed inside the FPGA chip. Therefore, the present invention can achieve online real-time measurement of beam information at the sub-microsecond level.

[0050] 2. The present invention can solve the phase of the beam relative to the cavity pressure (i.e., the beam synchronization phase) in the closed-loop operation mode of the RF cavity, and the calculation result is no longer affected by the phase drift caused by environmental factors; in addition, since the algorithm uses the steady-state average value for calculation, it is insensitive to instantaneous measurement noise and can achieve higher measurement accuracy.

[0051] 3. The measurement result of the present invention is not affected by the detuning of the cavity. Even if the cavity is far away from the resonance state, the present invention can accurately solve the beam information.

[0052] In summary, the present invention can be widely used in particle accelerators. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the detailed description of the preferred embodiments below. The accompanying drawings are only for the purpose of illustrating the preferred embodiments and are not to be considered as limiting the present invention. Throughout the accompanying drawings, the same reference numerals are used to represent the same components. In the accompanying drawings:

[0054] Figure 1 This is a flow chart of a method for online measurement of beam information according to an embodiment of the present invention.

[0055] Figure 2 4 is a block diagram of an online beam current information measurement system according to an embodiment of the present invention.

[0056] Figure 3The signal principle diagram of the embodiment of the present invention, wherein Figure (a) is a principle diagram of the signal normalization implemented in the embodiment of the present invention; Figure (b) is a schematic diagram of the forward voltage signal calculated in the embodiment of the present invention U f Steady-state values ​​in both no-beam and beam-current situations U F0 and U F1 Schematic diagram showing only the vector U F0 and U F1 The calculation process of the real part is exactly the same as that of the imaginary part.

[0057] Figure 4 The embodiment of the present invention is a steady-state forward voltage vector U F0 and U F1 Perform vector calculation to obtain the beam equivalent voltage vector V B Schematic diagram of the beam, where (a) is the amplitude and phase diagram of the beam, and (b) is U F0 and U F1 Schematic diagram of calculation of the imaginary and real parts.

[0058] Figure 5 is the beam equivalent voltage vector when the RF cavity works in a near-resonant state (detuning ≈ 0) in the embodiment of the present invention. V B The measurement results of Figure (a) are V c Waveform diagram of the real part (upper) and imaginary part (lower) of the signal; Figure (b) is U f Waveforms of the real (top) and imaginary (bottom) parts of the signal, and U F0 and U F1 The measurement results of the real part (upper) and the imaginary part (lower); Figure (c) shows the measurement results of the vector U F0 and U F1 Calculate vector V B The measured results.

[0059] Figure 6 is the beam equivalent voltage vector when the RF cavity works in a large detuning state (detuning angle ≈ 60 degrees) in the embodiment of the present invention. V B The measurement results of Figure (a) are Vc Waveform diagram of the real part (upper) and imaginary part (lower) of the signal; Figure (b) is U f Waveforms of the real (top) and imaginary (bottom) parts of the signal, and U F0 and U F1 The measurement results of the real part (upper) and the imaginary part (lower); Figure (c) shows the measurement results of the vector U F0 and U F1 Calculate vector V B The measured results.

[0060] Figure 7 Figure 2 is the beam information at different current intensities in an embodiment of the present invention, wherein Figure (a) shows the beam phase (black triangle) calculated by the present invention at different current intensities, the beam phase (gray circle) calculated by the dedicated beam measurement system, and the beam phase (gray diamond) calculated by the DESY method; Figure (b) on the right shows the beam intensity (black triangle) calculated by the present invention at different current intensities in an embodiment of the present invention, and the beam intensity (gray circle) calculated by the dedicated beam measurement system.

[0061] Figure 8 : The beam phase (black origin) calculated by the present invention under different cavity detuning in the embodiment of the present invention and the beam phase (gray origin) calculated by the DESY method.

[0062] Fig. 9 : is the deviation between the beam phase (gray) measured by BPM and the beam phase (red) measured by the present invention at different beam phases in an embodiment of the present invention.

[0063] Fig.10 1 is a flow chart of signal processing inside FPGA according to an embodiment of the present invention, wherein (a) is a schematic diagram of the structure of the measuring device, (b) is a diagram of the preprocessing structure, and (c) is a diagram of the CIC filter structure.

[0064] Fig.11 FIG. 4 is a structural diagram of an electronic device according to an embodiment of the present invention. DETAILED DESCRIPTION

[0065] It should be understood that the terms used herein are only for the purpose of describing specific example embodiments and are not intended to be limiting. Unless the context clearly indicates otherwise, the singular forms "one", "an" and "said" as used herein may also be meant to include plural forms. The terms "include", "comprise", "contain", and "have" are inclusive, and therefore specify the existence of stated features, steps, operations, elements and / or parts, but do not exclude the existence or addition of one or more other features, steps, operations, elements, parts, and / or combinations thereof. The method steps, processes, and operations described herein are not interpreted as necessarily requiring them to be performed in the specific order described or illustrated, unless the execution order is clearly indicated. It should also be understood that additional or alternative steps may be used.

[0066] Although the terms first, second, third, etc. can be used in the text to describe multiple elements, components, regions, layers and / or sections, these elements, components, regions, layers and / or sections should not be limited by these terms. These terms can only be used to distinguish an element, component, region, layer or section from another region, layer or section. Unless the context clearly indicates, terms such as "first", "second" and other numerical terms do not imply order or sequence when used in the text. Therefore, the first element, component, region, layer or section discussed below can be referred to as the second element, component, region, layer or section without departing from the teaching of the example embodiments.

[0067] For ease of description, spatially relative terms may be used herein to describe the relationship of one element or feature relative to another element or feature as shown in the figures, such as "inside", "outside", "inner side", "outer side", "below", "above", etc. Such spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation depicted in the figures.

[0068] Since the existing methods have limitations in operation mode, it is also difficult to obtain fine beam information with high time resolution. The method, system, device and medium for measuring beam information based on steady-state forward voltage vector provided by the present invention can measure the cavity incident signal of the RF cavity online. P f Get the original forward voltage of the RF cavity V f * ; The original forward voltage V f * Perform calibration and normalization to obtain the forward voltage V f ; The forward voltage V fScaling is performed to obtain the normalized forward voltage U f ; Based on the normalized forward voltage under no beam and beam conditions U f0 and U f1 , calculate the mean of their steady-state values ​​respectively U F0 and U F1 ; Based on the steady-state mean U F0 and U F1 Get the steady-state beam equivalent voltage V B ; Based on the steady-state beam equivalent voltage V B , and obtain the steady-state beam current intensity I B and beam synchronization phase Therefore, the present invention can directly solve the beam synchronization phase, and the calculation result is no longer affected by the phase drift caused by environmental factors.

[0069] The exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided in order to enable a more thorough understanding of the present invention and to fully convey the scope of the present invention to those skilled in the art.

[0070] Embodiment 1: Figure 1 As shown, the beam current information online measurement method based on the steady-state forward voltage vector relationship principle provided in this embodiment includes:

[0071] S1. Cavity sampling signal based on online measurement of RF cavity P t , cavity incident signal P f and cavity reflection signal P r Get the original cavity pressure of the RF cavity V c * , original forward voltage V f * and the original reverse voltage V r * .

[0072] In this embodiment, Figure 2As shown, an online measurement system is provided, including a digital low-level system 1, a solid-state power source 2, a directional coupler 3, an input coupler 4, a radio frequency cavity 5, a signal extraction coupler 6, a down-conversion module 7 and a host computer 8. The output end of the digital low-level system 1 is connected to the input end of the solid-state power source 2, the output end of the solid-state power source 2 is connected to the input end of the directional coupler 3, the output end (through port) of the directional coupler 3 is fed into the radio frequency cavity 5 through the input coupler 4, and the directional coupler 3 is used to extract the cavity incident signal of the radio frequency cavity 5 P f and cavity reflection signal P r The signal extraction coupler 6 is connected to the RF cavity 5 to extract the cavity sampling signal P t , cavity incident signal P f , cavity reflection signal P r and cavity sampling signal P t After down-conversion by down-conversion module 7, it is sent to digital low-level system 1. Digital low-level system 1 is based on cavity incident signal P f , cavity reflection signal P r and cavity sampling signal P t The corresponding digitized baseband in-phase and quadrature (I / Q) components are demodulated and uploaded to the host computer 8 via the data bus.

[0073] Furthermore, for cross-verification, a beam current detector (BCM) 9 may be provided at the entrance of the RF cavity 5 for online measurement of the beam current intensity; and a beam position detector (BPM) 10 may be provided at the exit of the RF cavity 5 for online measurement of the beam phase.

[0074] Furthermore, the digital low-level system 1 is provided with an FPGA (field programmable gate array), and the FPGA is provided with a digital signal processing module, which samples the cavity signal of the RF cavity. P t , cavity incident signal P f and reflected signal P r Processing is performed to obtain the corresponding three-way original voltage signals, including the original cavity pressure V c * , original forward voltage V f * and the original reverse voltage V r* Specifically, the cavity sampling signal is converted into P t , cavity incident signal P f and cavity reflection signal P r Down-converted to an intermediate frequency signal, the digital signal processing module of the digital low-level system 1 demodulates the intermediate frequency signal through I / Q to obtain three groups of original digital baseband signals, namely: the original cavity pressure of the RF cavity V c * , forward voltage V f * and reverse voltage V r * Generally speaking, in this embodiment P t Represents a radio frequency signal, such as a 352.21MHz radio frequency signal. V c It means that the digitized baseband signal has no RF frequency components, which are removed through analog and digital down-conversion.

[0075] It should be noted that the parameters involved in this embodiment, such as V c * , V f * , V r * , V c , U C , V f , U f , U F0 , U F1 , V B etc. are all in complex form, which can be expressed in the form of amplitude and phase, for example: V =| V | e j∠V , where | V | is the amplitude or modulus, ∠ V is the phase or argument; it can also be expressed as the real part plus the imaginary part, for example: V = V I + JbXj Q,in, V I is the real part or the in-phase component, V Q is the imaginary part or quadrature component, j Is an imaginary unit.

[0076] S2, based on the original cavity pressure V c * and forward voltage V f * The cavity pressure is obtained by calibration and normalization V c , forward voltage V f , and the normalized forward voltage U f .

[0077] In this embodiment, the original cavity pressure V c * and the original forward voltage V f * After calibration and normalization, the cavity pressure is obtained V c and forward voltage V f ,include:

[0078] Original cavity pressure V c * and forward voltage V f * You can use the formula: V f, cali = XV f * Get the forward voltage after calibration V f, cali , where the correction factor X is plural, X It is mainly used to compensate for the influence of RF signal transmission cables and high-power RF devices on the measurement results. X The existing technology can be used to solve it, which can be expressed as amplitude and phase (i.e. X =| X | e j∠X ) can also be expressed as the real part plus the imaginary part (i.e. X = X I + JXj Q) is not limited here.

[0079] Furthermore, if Figure 3 (a) shows the original cavity pressure V c * After a period of filling time (the time it takes for the RF cavity pressure to reach a steady state from 0), the steady-state cavity pressure will be maintained for a period of time for beam acceleration (flat-top time). Calculate the flat-top time s 1 and s The average value of the cavity pressure between 2 moments is the normalization coefficient V c, ss * ,use V c = V c * / V c, ss * Get the normalized cavity pressure V c After normalization V c The amplitude of the steady-state value is 1 and the phase is 0 degrees. Similarly, to ensure signal consistency, the forward voltage after calibration must be V f, cali Perform the exact same scaling to get the normalized forward voltage V f ,Right now V f = V f, cali / V c, ss * Among them, after normalization, the original cavity pressure at steady state is V c Can be used U C represents the steady-state normalized cavity pressure, which becomes unity 1, which is the point "1+0" on the complex plane. j ",Right now U C =1+0 j .

[0080] Furthermore, if Figure 3 (b) As shown in 2 β / (1+ β ) Scale forward voltage V f Get the normalized forward voltage U f ,Right now U f = 2 β / (1+ β ) V f ,in, β is the coupling coefficient. After scaling, in the absence of beam current, the forward voltage in steady state is U F0 The real part of V c The real part is equal, that is, Re( U F0 ) = Re( U C )=1.

[0081] S3. Solve the steady state with or without beam flow U f The vector difference of the beam equivalent voltage vector V B .

[0082] In this embodiment, based on the normalized V c and V f Establishing the cavity differential equation

[0083] ;

[0084] Among them, the signal V c0 and V c1 are the cavity pressures without and with beam, respectively. V c ,Signal V f0 and V f1 are the forward voltages without beam current and with beam current respectively. V f ,Signal V b is the beam equivalent voltage; Δ ω 0 and Δ ω 1 is the cavity detuning without beam and with beam, ω 0.5 is the half bandwidth of the cavity, which is not affected by the beam current.

[0085] Exploit 2 β / (1+ β ) Scale forward voltage V f Get the normalized forward voltage U f ,Right now U f= 2 β / (1+ β ) V f ,in, β is the coupling coefficient, the formula is simplified to:

[0086] ;

[0087] Among them, the signal U f0 and U f1 are the forward voltages without beam current and with beam current respectively. U f .

[0088] Assuming that the RF cavity operates in closed-loop mode and the beam load is fully compensated, the cavity pressure V c In the case of beam flow or no beam flow, the values ​​are approximately equal, that is, V c0 ≈ V c1 ,and V c Reaching steady state (steady state means the signal V c Approximately does not change with time, that is, d V c / d t ≈ 0). Assume that the cavity detuning remains approximately constant during the beam pulse, i.e., Δ ω 0 ≈ Δ ω 1; Based on the above preconditions, if the left side of the equations is equal, the right side should also be equal, that is,

[0089] ;

[0090] Further obtain the beam equivalent voltage V b :

[0091] ;

[0092] Assuming that the forward voltage reaches a steady state, calculate the forward voltage with and without beam current. U f The steady-state value of U F1 and U F0 , U F1 andU F0 Will no longer change with time. Further, the vector difference between the two is calculated to obtain:

[0093] ;

[0094] in, V B Beam equivalent voltage V b steady-state value.

[0095] In this embodiment, the forward voltage under the two conditions of beam current and no beam current is used to determine the forward voltage signal under the two conditions of no beam current and beam current. U f0 and U f1 , calculate the mean of their steady-state values ​​respectively U F0 and U F1 Among them, no beam refers to the time period before the beam arrives or after the beam ends, and beam refers to the time period during the beam passing through, such as Figure 3 (b) Figure 4 (b) and Figure 5 (b). Since the measured signal will inevitably be mixed with high-frequency noise, it is necessary to U f0 Qianhe U f1 Take the average value in a given time interval U F0 and U F1 .Right now

[0096] ;

[0097] S4. Vector operations.

[0098] In this embodiment, Figure 4 (b) Figure 5 (b) and Figure 6 (b) shows that for the vector U F0 and U F1 Perform vector difference calculation to obtain the steady-state beam equivalent voltage V B ,Right now .because V B , U F0 and U F1are all two-dimensional vectors, and their subtraction operations can be converted into complex operations, that is,

[0099] ;

[0100] in, U F0I and U F0Q They are U F0 The real and imaginary parts of U F1I and U F1Q They are U F1 The real and imaginary parts of V BI and V BQ They are V B The real and imaginary parts of .

[0101] S5, through the steady-state beam equivalent voltage V B , calculate the steady-state beam current I B and beam synchronization phase In this embodiment, based on the beam equivalent voltage V B Calculate beam current I B and beam synchronization phase ,include:

[0102] ;

[0103] in, r / Q is the geometric factor of the cavity, G The value of is the current normalized cavity pressure V c The corresponding true cavity pressure value, Q L is the cavity loaded quality factor, is the amplitude of the beam equivalent voltage, is the phase of the equivalent voltage.

[0104] Note that since this embodiment reduces the cavity pressure V c Normalized to 1, formula (3) solves | V B | is also a dimensionless quantity, so we need to convert | V b |Multiply by a factor GIt becomes a beam equivalent voltage with clear physical dimensions (such as kilovolts, megavolts). G The value of is the current normalization V c The corresponding real cavity pressure value (in this embodiment, the real value of the cavity pressure is about 60 kV) is taken as an example and is not limited to this. In addition, since the vector V B is the steady-state value, the required beam current intensity I B and beam phase It is also the steady-state result, that is, the average value of the beam pulse after it reaches steady state.

[0105] The application and verification process of the online beam current information measurement method based on the steady-state forward voltage vector relationship principle of the present invention are described in detail below through specific embodiments.

[0106] The solid-state power source 2 used in this embodiment has an output power of about 30 kW; the RF cavity 5 is a room temperature beam cavity with a cavity resonant frequency of 352.21 MHz and a loaded quality factor of Q L About 10000, geometric factor r / Q is 74; the clock frequency of the FPGA in the digital low-level system 1 is 117.402 MHz, and the original cavity pressure transmitted to the host computer 8 is V c * , original forward voltage V f * The data sampling rate is 8.3859 MHz; beam current intensity detector 9 (BCM, digital board model: SIS8300-KU MTCA.4, sampling rate: 5.49 MHz) and beam position detector 10 (BPM, digital board model: SIS8300-KU MTCA.4: sampling rate: 5.87MHz).

[0107] Based on the above parameter settings, the beam current information online measurement method based on the steady-state forward voltage vector relationship principle provided in this embodiment includes:

[0108] 1. If Figure 2 As shown, the original cavity pressure of the RF cavity is measured V c * , forward voltage V f * and reverse voltage V r * .

[0109] 1. Use the signal extraction coupler 6 to extract the cavity pressure signal online P t , using directional coupler 3 to measure the cavity incident signal online P f and reflected signal P r , where the cavity pressure signal P t , cavity incident signal P f and reflected signal P r Both are 352.21 MHz RF signals.

[0110] 2. After the above RF signal is down-converted, digitized and IQ demodulated in sequence, the digital low-level system 1 obtains the digitized original baseband voltage signal, i.e., the original cavity pressure V c * , original forward voltage V f * and the original reverse voltage V r * The digital low level system 1 uploads the above baseband signal to the data bus.

[0111] 2. Signal calibration, normalization and standardization.

[0112] According to the original cavity pressure V c * and the original forward voltage V f * Achieve signal calibration and normalization, including:

[0113] 1. Original forward voltage signal V f * calibration.

[0114] The host computer 8 reads the current raw cavity pressure online from the data bus V c * and the original forward voltage V f * First, according to V f, cali = XV f * Solve for the calibrated forward signal. Note: The cavity pressure signal is usually used as a reference signal and does not need to be calibrated. The complex multiplication operation can be performed as follows:

[0115] ;

[0116] In the formula, V f, caliI and V f, caliQ They are V f, cali The real and imaginary parts of V fI * and V fQ * They are V f * The real and imaginary parts of X I and X Q The calibration coefficients are X The real and imaginary parts of .

[0117] 2. Normalization and standardization of original cavity pressure V c * and the original forward voltage V f * .

[0118] like Figure 3 As shown in (a), after a period of filling time, the original cavity pressure V c * To reach a steady state, theoretically, when the RF cavity is working in a closed loop, whether there is a beam or not, V c * The steady state should be maintained throughout the flat top time. Figure 5 (a) and Figure 6 As shown in (a), although the existing beam loading compensation technology can eliminate most of the beam loading effect, a small transient caused by the beam (the beam arrives at 150 μs, lasts for 50 μs, and ends at 200 μs) can still be observed in the cavity pressure signal. V c Fluctuations. Especially at the beam arrival time (about 150 microseconds) and the end time (about 200 microseconds), V c Spikes are observed in the signal. To avoid the influence of instantaneous spikes on the calculation results, Figure 3 (a). Select two points before the beam reaches s 1 and s 2. Calculation V c * exist s 1 ands The average value between 2 V c,ss * ,Right now V c,ss * =mean( V c * | s1→s2 ).like Figure 5 As shown in Figures 5(a) and 5(b), the cavity pressure reaches a steady state at 100 microseconds, and the beam reaches the cavity at about 150 microseconds. s 1 can be selected between 120 and 140 microseconds. s 2 can be selected as 149 microseconds. Taking this as an example, the calculation process of finding the average value can be directly called by Python. numpy.mean function.

[0119] 3. The original cavity pressure V c * , original forward voltage V f * Normalization:

[0120] ;

[0121] Among them, the normalized cavity pressure V c The steady-state value U C 1+0 j .

[0122] 4. Use 2 β / (1+ β ) Scale forward voltage V f Get the normalized forward voltage U f , Right now:

[0123] ;

[0124] in, β is the coupling coefficient, for the room temperature cavity, β Generally close to 1, for a superconducting cavity, β It can generally be considered to be infinite.

[0125] 3. Calculate the steady-state forward voltage.

[0126] In the two cases of no beam and beam, the forward voltage signal is calculated using formula (1) U f ( t) within a given time range, and obtain two steady-state vectors U F0 Qianhe U F1 .like Figure 3 As shown in (b), we can select a flat-top time before the beam arrives and calculate the average value to get U F0 , or you can choose a flat-top time after the beam ends to calculate U F0 .like Figure 5 (b) and Figure 6 As shown in (b), this embodiment selects the time interval after the beam to calculate U F0 .in, t 1≈227 microseconds, t 2≈239 microseconds. The start of the average calculation t 1. End time t The selection of 2 is taken as an example, but is not limited to this. When the beam passes through, you can select U f The signal is close to steady state (that is, when high-frequency noise is not considered) U f / dt≈0) U F1 In this embodiment, if Figure 5 (b) and Figure 6 As shown in (b), t 3≈173 microseconds, t 4≈185 microseconds. Start of average calculation t 3. End time t The selection of 4 is taken as an example and is not limited to this. It is worth noting that Fig.10 When the FPGA chip shown in the figure implements the operation, since it shares the same CIC filter, it is necessary to ensure that t 2. t 1 and t 4. t 3 are equal in time interval, that is t 4─ t 3= t 2─ t 1. This requirement does not apply when using a host computer for calculation.

[0127] 4. Calculate the steady-state forward voltage and beam current intensity in turn I B and beam synchronization phase .

[0128] according to U F0 and UF1 The steady-state beam equivalent voltage is calculated using formula (2) V B , and according to V B The beam current intensity is calculated using formula (3): I B and beam synchronization phase Note: According to the definition of beam synchronization phase, Figure 4 (b) V B The phase of is not equivalent to the beam phase and needs to be converted using formula (3).

[0129] 5. Online experimental verification.

[0130] The experiment of this example has been verified at the European Spallation Neutron Source (Lund, Sweden). Figure 2 As shown, a beam current detector (BCM) is installed upstream of the RF cavity for online measurement of the beam current; a beam position detector (BPM) is installed downstream of the RF cavity for online measurement of the beam phase. Further, the beam current and phase calculated in this embodiment are compared with the measured values ​​of BCM and BPM.

[0131] 1. If Figure 7 (a) shows the comparison of the beam phase measurement results (grey circles) of BPM at different flux intensities with the calculation results (black triangles) of this embodiment. The calculation results of the DESY method (grey diamonds) are also compared. Figure 7 (b) The measured results of the BCM beam current under different current intensities (grey circles) and the calculated results of this embodiment (black triangles). Figure 7 (a) and Figure 7 In (b), the macro bunch length of the beam is 50 microseconds, and the RF cavity works in closed-loop mode and resonant state. It can be seen that the measured results are in good agreement with the calculated results of this patent, and the beam current intensity measured by this patent is more accurate than that of the DESY method.

[0132] 2. If Figure 8 As shown, the measurement results of the beam phase (black) of the DESY method (gray) and the present invention under different detuning conditions are compared. Among them, the macro bunch length of the beam is 50 microseconds, the RF cavity works in closed-loop mode and detuned state, and the beam intensity and phase are 60 mA and -88 degrees, respectively. It can be seen that when the RF cavity detuning is close to 0, the DESY method can obtain an accurate beam phase (i.e. -88 degrees), and when the RF cavity detuning is large, the measurement results of the DESY method will be affected by the detuning. In contrast, no matter how the RF cavity detuning changes, the present invention can always obtain an approximately correct beam phase with an error within ±1 degree.

[0133] 3. Since the present invention uses the steady-state average value for calculation, it is insensitive to instantaneous measurement noise, so the present invention has higher measurement accuracy. Fig. 9 The figure shows a comparison of the deviation between the quantity phase measured by the BPM and the beam phase obtained by the present invention under different beam phases. It can be seen that the present invention can achieve higher measurement accuracy.

[0134] Embodiment 2: The above-mentioned embodiment 1 provides an online measurement method for beam current information based on the principle of steady-state forward voltage vector relationship. Correspondingly, this embodiment provides an online measurement device for beam current information based on the principle of steady-state forward voltage vector relationship. The device provided in this embodiment can implement the online measurement method for beam current information based on the principle of steady-state forward voltage vector relationship of embodiment 1, and the device can be implemented by software, hardware or a combination of software and hardware. For the convenience of description, the description of this embodiment is divided into various units and described separately according to their functions. Of course, the functions of each unit can be implemented in the same or one or more software and / or hardware during implementation. For example, the device can include integrated or separate functional modules or functional units to perform the corresponding steps in each method of embodiment 1. Since the device of this embodiment is basically similar to the method embodiment, the description process of this embodiment is relatively simple. For relevant parts, please refer to the partial description of embodiment 1. The embodiment of the online measurement device for beam current information based on the principle of steady-state forward voltage vector relationship provided by the present invention is only schematic.

[0135] Specifically, the beam current information online measurement device based on the steady-state forward voltage vector relationship principle provided in this embodiment is implemented based on FPGA, and includes:

[0136] The forward voltage acquisition module is configured to measure the cavity incident signal of the RF cavity online. P f Get the original forward voltage of the RF cavity V f * ;

[0137] The pre-processing module is configured to convert the raw forward voltage V f * Perform calibration and normalization to obtain the forward voltage V f ;

[0138] Standardized modules, configured to convert the forward voltage V f Scaling is performed to obtain the normalized forward voltage U f ;

[0139] The steady-state mean calculation module is configured based on the normalized forward voltage under both no-beam and beam conditions. U f0 and U f1 , calculate the mean of their steady-state values ​​respectively U F0 and U F1 ;

[0140] The vector operation module is configured to be based on the steady-state value mean U F0 and U F1 Get the steady-state beam equivalent voltage V B ;

[0141] The beam information extraction module is configured based on the steady-state beam equivalent voltage V B , and obtain the steady-state beam current intensity I B and beam synchronization phase .

[0142] It should be noted that the core algorithms of the signal calibration normalization, steady-state average solution, vector operation and beam information extraction in this embodiment do not involve complex digital signal processing algorithms (for example: signal derivative operation, curve fitting, finite length unit impulse response filter, etc.), and their operation process can be completely implemented inside the FPGA chip (without the need for operation on the host computer through data communication). As an example, Fig.10 As shown in (a), the preprocessing module (signal calibration, normalization and standardization) only involves multiplication and addition operations. Both normalization and standardization processing can be completed using the internal multiplier of the FPGA, and the steady-state value mean calculation can be implemented by the existing mature CIC filter (integral comb filter) and 4 registers (accessed separately). Vector operations can be implemented by the adder inside the FPGA. Beam information extraction can be implemented by the mature CORDIC (coordinate rotation calculation method) algorithm. Therefore, the present invention can realize sub-microsecond level online real-time beam information extraction.

[0143] Furthermore, the preprocessing module can be constructed according to formula (4): Fig.10 (b) The multiplication and addition operations are implemented as shown.

[0144] Further, Fig.10 The register in (a) contains the external trigger signal. t = t 2 Moments and t = tAt 4 seconds, the external trigger signal will output the forward voltage signal of the CIC filter. U f0 and U f1 The average value of: U F0 and U FI The signals are latched into the registers inside the FPGA to obtain the steady-state average value of the forward signal without beam current. U F0 and the steady-state average of the forward signal under beam flow U F1 .

[0145] Further, Fig.10 Parameters of the CIC filter in (c) D , which means to extend the current data stream D clock cycles. Assume that the FPGA clock cycle is T clk microseconds, then D The clock will delay microseconds. CIC filter can achieve The microsecond data stream is averaged. Therefore, Need and t 2─ t 1 and t 4─ t 3 are equal, that is D= ( t 2─ t 1) / T clk =( t 4─ t 3) / T clk .

[0146] Embodiment 3: This embodiment provides an electronic device corresponding to the online measurement method of beam current information based on the principle of steady-state forward voltage vector relationship provided in Embodiment 1. The electronic device can be an electronic device for a client, such as a mobile phone, a laptop computer, a tablet computer, a desktop computer, etc., to execute the method of Embodiment 1.

[0147] like Fig.11As shown, the electronic device includes a processor, a memory, a communication interface and a bus, and the processor, the memory and the communication interface are connected through the bus to complete mutual communication. The bus can be an Industry Standard Architecture (ISA) bus, a Peripheral Component (PCI) bus or an Extended Industry Standard Component (EISA) bus, etc. The memory stores a computer program that can be run on the processor. When the processor runs the computer program, it executes the method of Embodiment 1. The implementation principle and technical effect are similar to those of Embodiment 1 and will not be repeated here. Those skilled in the art can understand that Fig.11 The structure shown in the figure is only a block diagram of a part of the structure related to the scheme of the present application, and does not constitute a limitation on the computing device to which the scheme of the present application is applied. The specific computing device may include more or fewer components than shown in the figure, or combine certain components, or have a different arrangement of components.

[0148] In a preferred embodiment, the logic instructions in the above-mentioned memory can be implemented in the form of a software functional unit and can be stored in a computer-readable storage medium when it is sold or used as an independent product. Based on this understanding, the technical solution of the present application can be essentially or partly embodied in the form of a software product that contributes to the prior art. The computer software product is stored in a storage medium, including several instructions to enable a computer device (which can be a personal computer, server, or network device, etc.) to execute all or part of the steps of the method described in each embodiment of the present application. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), optical disk and other media that can store program codes.

[0149] In a preferred embodiment, the processor may be a central processing unit (CPU), a digital signal processor (DSP) or other general-purpose processors of various types, which are not limited herein.

[0150] Embodiment 4: This embodiment provides a computer-readable storage medium storing one or more programs, wherein the one or more programs include computer instructions. When the computer instructions are executed by a computer, the computer executes the method provided in the above-mentioned embodiment 1.

[0151] Embodiment 5: This embodiment provides a computer program product. The computer program product may include a computer program stored on a computer-readable storage medium. The computer program includes program instructions. When the program instructions are executed by a computer, the computer can execute the method provided in the above-mentioned embodiment 1. Its implementation principle and technical effects are similar to those of embodiment 1 and will not be repeated here.

[0152] In a preferred embodiment, the computer-readable storage medium may be a tangible device that holds and stores instructions used by the instruction execution device, such as but not limited to an electrical storage device, a magnetic storage device, an optical storage device, an electromagnetic storage device, a semiconductor storage device, or any combination thereof. The computer-readable storage medium stores computer program instructions that cause the computer to execute the method provided in the first embodiment.

[0153] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (apparatus), and computer program products according to the embodiments of the present application. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0154] These computer program instructions may also be stored in a computer readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture including an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0155] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process in the computer or other programmable device. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0156] Each embodiment in this specification is described in a progressive manner, and the same and similar parts between the embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. In the description of this specification, the description of reference terms "a preferred embodiment", "further", "specifically", "in the present embodiment", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the embodiment of this specification. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples without contradiction.

[0157] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A beam current information online measurement method based on the principle of steady-state forward voltage vector relationship, characterized in that: include: Online measurement of the cavity incident signal of the RF cavity P f Get the original forward voltage of the RF cavity V f * ; The original forward voltage V f * Perform calibration and normalization to obtain the forward voltage V f ; The forward voltage V f Scaling is performed to obtain the normalized forward voltage U f ; Normalized forward voltage under no beam and beam conditions U f0 and U f1 , calculate the mean of their steady-state values ​​respectively U F0 and U F1 ; Based on the steady-state mean U F0 and U F1 Get the steady-state beam equivalent voltage V B ; Based on the steady-state beam equivalent voltage V B , and obtain the steady-state beam current intensity I B and beam synchronization phase .

2. The method for online measurement of beam information according to claim 1, characterized in that: The forward voltage V f Scaling is performed to obtain the normalized forward voltage U f : ； in, β is the coupling coefficient.

3. The method for online measurement of beam information according to claim 1, characterized in that: Normalized forward voltage under no beam and beam conditions U f0 and U f1 , calculate the mean of their steady-state values ​​respectively U F0 and U F1 ; ； In the formula, under the condition of no beam, the time interval is t 1 is the starting time, t 2 is the end time, in the time interval under beam conditions t 3 is the starting time, t 4 is the end time.

4. The method for online measurement of beam information according to claim 1, characterized in that: Based on the steady-state mean U F0 and U F1 Get the steady-state beam equivalent voltage V B : 。 5. The method for online measurement of beam information according to claim 1, characterized in that: Based on beam equivalent voltage V B Calculate beam current I B and beam synchronization phase ,include: ； in, is the geometric factor of the cavity, and the value of G is the current normalized cavity pressure V c The corresponding true cavity pressure value, is the cavity loaded quality factor, is the amplitude of the beam equivalent voltage, is the phase of the equivalent voltage.

6. The method for online measurement of beam information according to claim 4 or 5, characterized in that: Steady-state beam equivalent voltage V B The calculation of is obtained by solving the cavity differential equation, the specific process is: Establish the cavity differential equation: ； in, V c0 and V c1 are the cavity pressures without beam and with beam respectively. V c ,Signal V f0 and V f1 are the forward voltages without beam current and with beam current respectively. V f , V b is the beam equivalent voltage, Δ ω 0 and Δ ω 1 is the cavity detuning without beam and with beam, ω 0.5 is the half bandwidth of the cavity, β is the coupling coefficient, j is an imaginary unit; Using the normalized forward voltage U f Simplifying the right side of the above differential equation, we get the following formula: ； When the RF cavity operates in closed-loop mode and the beam load is fully compensated, the cavity pressure V c In the case of beam flow or no beam flow, the values ​​are approximately equal, that is, V c0 ≈ V c1 ,and V c Reaching steady state, that is, d V c / d t ≈0; the cavity detuning remains approximately constant during the beam pulse, i.e., Δ ω 0≈Δ ω 1; Based on the above conditions, if the left side of the equations are equal, the right side should also be equal, that is: ； Obtain the beam equivalent voltage V b : ； When the forward voltage reaches a steady state, calculate the forward voltage with and without beam current respectively. U f The steady-state value of U F1 and U F0 , U F1 and U F0 Will no longer change with time, and the vector difference between the two is calculated to obtain: ； in, V B Beam equivalent voltage V b steady-state value.

7. An online beam current information measurement device based on the principle of steady-state forward voltage vector relationship, characterized in that: The device is implemented based on FPGA and includes: The forward voltage acquisition module is configured to measure the cavity incident signal of the RF cavity online. P f Get the original forward voltage of the RF cavity V f * ; The pre-processing module is configured to convert the raw forward voltage V f * Perform calibration and normalization to obtain the forward voltage V f ; Standardized modules, configured to convert the forward voltage V f Scaling is performed to obtain the normalized forward voltage U f ; The steady-state mean calculation module is configured based on the normalized forward voltage under both no-beam and beam conditions. U f0 and U f1 , calculate the mean of their steady-state values ​​respectively U F0 and U F1 ; The vector operation module is configured to be based on the steady-state value mean U F0 and U F1 Get the steady-state beam equivalent voltage V B ; The beam information extraction module is configured based on the steady-state beam equivalent voltage V B , and obtain the steady-state beam current intensity I B and beam synchronization phase .

8. An electronic device, characterized in that: include: at least one processor; and a memory communicatively connected to the processor; wherein the memory stores instructions executable by the processor, and the instructions are executed by the processor so that the processor can execute the method according to any one of claims 1-6.

9. A computer-readable storage medium storing one or more programs, characterized in that: The one or more programs include computer instructions for causing a computer to execute the method according to any one of claims 1-6.

Images