Method, device and equipment for automatically measuring Lorentz detuning coefficient of superconducting cavity and medium

Abstract

The invention discloses a superconducting cavity Lorentz detuning coefficient automatic measurement method, device and equipment and a medium, and the method comprises the steps: setting power source excitation and pulse parameters based on the electromagnetic characteristics of a superconducting cavity; performing superconducting cavity pulse field building based on the set pulse parameters, and obtaining a cavity voltage signal and a forward voltage signal; establishing a cavity differential equation based on the cavity pressure signal and the forward voltage signal, and solving the cavity differential equation to obtain cavity dynamic detuning corresponding to power source excitation; calculating a static Lorentz delta F and a steady-state cavity field E corresponding to power source excitation based on cavity dynamic detuning; power source excitation is changed, the measurement process is repeated, multiple sets of static Lorentz delta F and steady-state cavity fields E are obtained, and a # imgabs0 # scatter diagram is drawn for linear fitting to obtain the Lorentz detuning coefficient. Therefore, the Lorentz detuning coefficient can be automatically calculated, the measurement efficiency is greatly improved, and meanwhile, the measurement precision is superior to that of a traditional method.

Description

Technical Field

[0001] The present invention relates to an automated measurement method, device, equipment and medium for the Lorentz Force Detune (LFD) coefficient of a superconducting cavity, and relates to the field of particle accelerators. Background Art

[0002] Accelerators play an important role in fields such as materials, scientific research, and medicine. Currently, radio frequency superconducting technologies have been selected for accelerators under construction such as CiADS, HIAF, and HEPS. A superconducting cavity is a core component in a superconducting accelerator, mainly used for accelerating charged particles. It has advantages such as low loss and high gradient, and is suitable for accelerating high-intensity beams in continuous wave (CW) or long-pulse modes. However, due to its narrow working bandwidth, generally in the range of dozens to hundreds of hertz, a superconducting cavity is extremely vulnerable to interference from factors such as Lorentz detuning and helium pressure fluctuations, resulting in frequency detuning and then triggering faults, which affects the long-term stable operation of the accelerator.

[0003] LFD refers to the fact that a radio frequency field excites the cavity wall current to generate a Lorentz force. Under the action of the Lorentz force, the volume of the superconducting cavity will undergo a small deformation, that is, it will contract at the cavity neck and expand near the equator of the cavity body, thus causing a shift in the eigenfrequency of the superconducting cavity. LFD not only affects the stability of the electromagnetic field in the superconducting cavity, increases the radio frequency power demand, but also triggers the electromagnetic-mechanical coupling oscillation of the superconducting cavity in severe cases, which is extremely likely to cause group cavity failures.

[0004] The LFD coefficient is a key parameter for calculating the magnitude of the Lorentz force and measuring the mechanical properties of the cavity. Currently, traditional measurement methods for the LFD coefficient usually rely on the continuous wave self-excitation oscillation mode of the cavity, and are achieved by manually adjusting the cavity excitation amplitude and measuring the corresponding frequency change. Although this method can measure the LFD coefficient, the measurement process is time-consuming and inefficient, and requires a large amount of machine running time. In addition, for the same cavity, due to the long measurement time, factors such as helium pressure fluctuations and environmental vibrations will significantly affect the measurement accuracy.

[0005] Therefore, how to accurately measure LFD is crucial for ensuring the stable operation of the superconducting cavity. There is an urgent need for a more accurate automated measurement method to address the deficiencies of the existing technology. Summary of the Invention

[0006] The present invention aims to at least solve one of the technical problems existing in the prior art. For this purpose, in view of the above problems, the object of the present invention is to provide an automated measurement method, device, equipment and medium for the Lorentz detuning coefficient of a superconducting cavity, which can greatly improve the measurement efficiency, and at the same time the measurement accuracy is better than the traditional method.

[0007] In order to achieve the above invention object, the technical solution adopted by the present invention is as follows: In a first aspect, the present invention provides an automated measurement method for the Lorentz detuning coefficient of a superconducting cavity. The method includes: Based on the electromagnetic characteristics of the superconducting cavity, set the power source excitation and pulse parameters; Based on the set pulse parameters, perform pulsed field building on the superconducting cavity and obtain the cavity voltage signal and the forward voltage signal; Based on the cavity voltage signal and the forward voltage signal, establish a cavity differential equation, and solve the cavity differential equation to obtain the cavity dynamic detuning corresponding to the power source excitation; Based on the cavity dynamic detuning, calculate the static Lorentz Δ corresponding to the power source excitation F and the steady-state cavity field E ; Change the power source excitation and repeat the above measurement process to obtain multiple sets of static Lorentz Δ F and the steady-state cavity field E , and plot a scatter plot and perform linear fitting to obtain the Lorentz detuning coefficient.

[0008] In some possible embodiments, the pulse parameters include the pulse width, the repetition period, and the pulse amplitude, where the pulse width is significantly greater than the field building time, and the repetition period is greater than the pulse width.

[0009] In some possible embodiments, based on the cavity voltage signal and the forward voltage signal, establishing a cavity differential equation and solving the cavity differential equation to obtain the cavity dynamic detuning corresponding to the power source excitation includes: Based on the cavity voltage signal and the forward voltage signal, establish a cavity differential equation; Decompose the cavity voltage signal and the forward voltage signal into real and imaginary parts and substitute them into the cavity differential equation to obtain a real-imaginary separated binary linear equation; Solve the binary linear equation to obtain the cavity dynamic detuning.

[0010] In some possible embodiments, the calculation formula for the cavity dynamic detuning is: ; where and are the real and imaginary parts of the cavity voltage signal V c respectively; and are the real and imaginary parts of the forward voltage signal V f respectively, and are the differential real and imaginary parts of the cavity voltage signal V c respectively, K is a set parameter, ,​β is the coupling coefficient of the cavity, ω 0.5 is the half bandwidth of the cavity, Δ ω is the detuning of the cavity, is the dynamic detuning of the cavity.

[0011] In some possible implementation manners, based on the dynamic detuning of the cavity, calculate the static Lorentz Δ corresponding to the power source excitation F and the steady-state cavity field E， including: Calculate the dynamic detuning Δ of the cavity f the detuning Δ caused by the helium pressure in it f HE ; Subtract Δ in the dynamic detuning Δ of the cavity f to obtain a new detuning variable Δ f HE 2, where f , where, Δ is the static Lorentz detuning, F is the dynamic Lorentz detuning, Δ σf lfd is the microphonic detuning; f micro Based on the new detuning variable Δ f 2, calculate the static Lorentz detuning Δ of the i th pulse under the current power source excitation F E i , and at the same time calculate the steady-state cavity field E i corresponding to the same time period under the current power source excitation.

[0012] In some possible implementation manners, the static Lorentz detuning Δ F i and the steady-state cavity field E i are respectively: ; ; where t 2 is the end time of the pulse, T m is the period corresponding to the main frequency component of the microphony, t 1 = t 2 - T m is the integration start time used to calculate the static Lorentz detuning Δ F i , E peak is the peak electric field.

[0013] In some possible embodiments, the power source excitation is changed, and the above measurement process is repeated to obtain multiple sets of static Lorentz Δ F and the steady-state cavity field E , and a scatter plot is plotted for linear fitting to obtain the Lorentz detuning coefficient. It includes: Keep the current power source excitation unchanged, and output T rp as a period N consecutive rectangular pulses, and calculate the steady-state cavity field of the i th pulse and the static Lorentz detuning Δ E i respectively, and average F i and Δ E i to obtain the average steady-state cavity field F i and the average static Lorentz detuning Δ E to obtain the first set ( F , Δ E ); F Change the power source excitation, repeat the above process for calculation to obtain multiple sets ( ， , Δ E ); F Since the static Lorentz detuning Δ is proportional to the square of the steady-state cavity field F , the Lorentz detuning coefficient is determined by linear fitting E , where is the Lorentz detuning coefficient. , K L is the Lorentz detuning coefficient.

[0014] In a second aspect, the present invention also provides an automated measurement device for the Lorentz detuning coefficient of a superconducting cavity, including: A parameter setting unit configured to set the power source excitation and pulse parameters based on the electromagnetic characteristics of the superconducting cavity; A signal acquisition unit configured to perform pulsed field building of the superconducting cavity based on the set pulse parameters and obtain the cavity voltage signal and the forward voltage signal; A dynamic detuning calculation unit configured to establish a cavity differential equation based on the cavity voltage signal and the forward voltage signal and solve the cavity differential equation to obtain the cavity dynamic detuning corresponding to the power source excitation; A static Lorentz calculation unit configured to calculate the static Lorentz Δ F corresponding to the power source excitation and the steady-state cavity field E ; The Lorentz detuning coefficient calculation unit is configured to change the power source excitation and repeat the above measurement process to obtain multiple sets of static Lorentz Δ F and the steady-state cavity field E and plot a scatter plot and perform linear fitting to obtain the Lorentz detuning coefficient.

[0015] In a third aspect, the present invention also provides an electronic device, including: at least one processor; and a memory communicatively connected to the processor; wherein, the memory stores instructions executable by the processor, and when the instructions are executed by the processor, the processor is enabled to execute the above method.

[0016] In a fourth aspect, the present invention also provides a computer-readable storage medium storing one or more programs, the one or more programs including computer instructions for causing a computer to execute the above method.

[0017] Due to the above technical solutions adopted by the present invention, it has the following characteristics: 1. The present invention can automatically calculate the Lorentz detuning coefficient, and shorten the measurement time of the Lorentz detuning coefficient by 5 to 6 times compared with the traditional method, greatly improving the measurement efficiency. At the same time, the measurement accuracy is better than the traditional method, and it can online monitor the whole process of the dynamic change of the cavity detuning caused by LFD, laying a foundation for improving the operation stability of the superconducting cavity.

[0018] 2. The present invention measures and analyzes the Lorentz detuning coefficient by reading the radio frequency signals under different power source excitations during the pulse mode operation. Among them, the acquisition, down-conversion, and IQ demodulation of the radio frequency signals can all be completed by a general-purpose digital low-level system, and the processing of data and the like can all be deployed on a general-purpose upper computer. None of the above applications require additional hardware devices.

[0019] In summary, the present invention can be widely applied to particle accelerators, especially suitable for the scenario of parallel monitoring of multiple cavities in large particle accelerators. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] By reading the following detailed description of the preferred embodiments, various other advantages and benefits will become clear to those of ordinary skill in the art. The drawings are only for the purpose of showing the preferred embodiments and are not considered to be a limitation of the present invention. Throughout the drawings, the same reference numerals are used to represent the same components. In the drawings: Figure 1 It is a schematic diagram of the Lorentz detuning coefficient measured by the existing method.

[0021] Figure 2a It is a flowchart of the automatic measurement method for the Lorentz detuning coefficient of the superconducting cavity according to the embodiment of the present invention.

[0022] Figure 2b It is a system block diagram for online measurement of the Lorentz detuning coefficient of a superconducting cavity in an embodiment of the present invention.

[0023] Figure 3a It is a schematic diagram of the cavity pressure, the amplitude and phase of the forward signal during pulsed operation in an embodiment of the present invention.

[0024] Figure 3b It is a schematic diagram of the loaded quality factor and the dynamic detuning of the cavity obtained from the cavity pressure and the forward signal in an embodiment of the present invention.

[0025] Figure 4 It is a schematic diagram of the principle for measuring the static Lorentz detuning in an embodiment of the present invention.

[0026] Figure 5a In an embodiment of the present invention, from the dynamic detuning Δ f of the cavity, the helium pressure detuning Δ f HE is subtracted, and the resulting detuning curve Δ f 2. The red horizontal line is the static Lorentz detuning Δ F .

[0027] Figure 5b It is the dynamic detuning Δ f 2 of the cavity measured at different peak electric fields and the corresponding static Lorentz detuning Δ F。

[0028] Figure 5c in an embodiment of the present invention. It is a scatter plot of the corresponding static Lorentz detuning ΔF and the square of the steady-state cavity field E 2 .

[0029] Figure 6a In an embodiment of the present invention, it shows the transfer function of the mechanical mode of the cavity obtained by using existing system identification techniques.

[0030] Figure 6b In an embodiment of the present invention, the transfer function of the entire mechanical mode of the cavity is identified based on the cavity field waveform and detuning data during electromechanical oscillation. The steady-state value of the transfer function is K L .

[0031] Figure 7 It is a structural diagram of the electronic device in an embodiment of the present invention. Detailed implementation manners

[0032] It should be understood that the terms used herein are for the purpose of describing particular example embodiments only and are not intended to be limiting. Unless the context clearly dictates otherwise, the singular forms "a", "an", and "the" as used herein may also include the plural forms. The terms "comprising", "including", "containing", and "having" are inclusive and thus specify the presence of stated features, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and / or combinations thereof. The method steps, processes, and operations described herein are not to be construed as necessarily requiring them to be performed in the particular order described or illustrated, unless the order of performance is explicitly stated. It should also be understood that additional or alternative steps may be used.

[0033] Although the terms first, second, third, etc. may be used herein 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 may be used only to distinguish one element, component, region, layer, or section from another. Unless the context clearly dictates otherwise, terms such as "first", "second", and other numerical terms when used herein do not imply an order or sequence. Thus, the first element, component, region, layer, or section discussed below may be referred to as a second element, component, region, layer, or section without departing from the teachings of the example embodiments.

[0034] For ease of description, spatial relative relationship terms may be used herein to describe the relationship of one element or feature shown in the figures to another element or feature, such as "inside", "outside", "inner side", "outer side", "below", "above", etc. Such spatial relative relationship terms are intended to include different orientations of the device in use or operation in addition to the orientation depicted in the figures.

[0035] Lorentz detuning coefficient K L characterizes the mechanical stability of the superconducting cavity, and the absolute value thereof is inversely proportional to the mechanical stability of the cavity. K L The larger it is, the more significant the frequency detuning of the cavity under the action of the Lorentz force and the less stable the mechanical performance. By K L it can quantify the influence of the Lorentz force on the cavity frequency, and further evaluate the stability of the superconducting cavity during high-power operation. The traditional method for measuring the LFD coefficient is usually based on the continuous-wave self-excited mode of the cavity, and it is necessary to manually adjust the cavity excitation amplitude and measure the corresponding frequency shift point by point to achieve. Although this method can measure K L, however, it has the disadvantages of low measurement efficiency and long time consumption. In addition, due to the long measurement period, factors such as helium pressure fluctuation and environmental vibration will introduce significant errors, limiting the measurement accuracy. As Figure 1 shown, it can be clearly seen that each measurement point is located on both sides of the fitting line, with large fluctuations, affecting the measurement accuracy. The automated measurement method, device, equipment and medium for the Lorentz detuning coefficient of a superconducting cavity provided by the present invention include: setting a power source excitation and pulse parameters based on the electromagnetic characteristics of the superconducting cavity; performing pulsed field building on the superconducting cavity based on the set pulse parameters and obtaining a cavity pressure signal and a forward voltage signal; establishing a cavity differential equation based on the cavity pressure signal and the forward voltage signal, and solving the cavity differential equation to obtain the dynamic detuning of the cavity corresponding to the power source excitation; calculating the static Lorentz Δ F and the steady-state cavity field E ; changing the power source excitation and repeating the above measurement process to obtain multiple sets of static Lorentz Δ F and the steady-state cavity field E , and plotting a scatter plot for linear fitting to obtain the Lorentz detuning coefficient. Therefore, the present invention can automatically calculate the Lorentz detuning coefficient, greatly improving the measurement efficiency, and at the same time the measurement accuracy is better than the traditional method.

[0036] 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 drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided so that the present invention can be more thoroughly understood and the scope of the present invention can be fully conveyed to those skilled in the art.

[0037] Example 1: As Figure 2a shown, the automated measurement method for the Lorentz detuning coefficient of a superconducting cavity provided in this embodiment includes: S1. Set the power source excitation and pulse parameters.

[0038] In this embodiment, since LFD is related to the change of the cavity field, when the cavity operates in the pulsed mode, it is easier to generate LFD. In addition, the externally-excited operation mode (GDR mode) is more likely to cause the electromechanical coupling oscillation of the cavity. Therefore, in this embodiment, it is necessary to set the superconducting cavity to operate in the self-excited mode (SEL mode).

[0039] In this embodiment, the pulse parameters mainly include the pulse width T pw , the repetition period T rp and the pulse amplitude. Among them, the setting of the pulse width T pw is related to the decay time constant τis related to τ The size is determined by Q L and ω 0 jointly: ; Among them, Q L is the loaded quality factor, ω 0 is the resonant angular frequency of the cavity, with the unit of radians per second. Its relationship with the cavity resonant frequency f 0 is: .

[0040] Furthermore, the cavity field building time T fill should generally be greater than 3 τ , to ensure that the electric field amplitude reaches 95% of the steady-state value. Therefore, in order to calculate the LFD detuning under a stable cavity field, the pulse width T pw needs to be significantly greater than the field building time (recommended T pw > 10 T fill ), and the repetition period T rp needs to be greater than T pw (recommended T rp > 10 T pw ). In this embodiment, the resonant frequency of the cavity is 162.5 MHz, and the loaded quality factor Q L is approximately, and the time constant τ is 1.2 milliseconds. The pulse width T pw can be set to 90 milliseconds, and the repetition period T rp is 1 second. Taking this as an example, it is not limited to this.

[0041] Furthermore, the power source excitation (i.e., the low-level output signal) V LLRF cannot be too large or too small. V LLRF Being too large will cause the electric field in the cavity to be too strong and lead to the quench of the superconducting cavity. V LLRF Being too small will cause the Lorentz detuning of the superconducting cavity to be too small and be overwhelmed by noise.

[0042] S2. Baseband signal reading: After the superconducting cavity is pulsed to build a field, the cavity voltage signal V c and the original forward voltage signal Vf * .

[0043] In this embodiment, as Figure 2b shown, a system for online measuring the Lorentz detuning coefficient of a superconducting cavity is further provided, including: 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 through port of the directional coupler 3 is fed into the superconducting cavity 5 through the input coupler 4. The sampling signal of the superconducting cavity 5 P t is fed back to the digital low-level system 1 through the signal extraction coupler 6; the directional coupler 3 collects the incident signal of the cavity P f and the reflected signal of the cavity P r and feeds them back to the digital low-level system 1. Each path of signals ( P t , P f , P r ) are down-converted by the down-conversion module 7 to obtain intermediate-frequency signals, and the intermediate-frequency signals are received by the digital low-level system 1. The digital low-level system 1 demodulates the corresponding digital baseband in-phase quadrature (I / Q) components from the received intermediate-frequency signals, and the I / Q components are output through the DAC and restored to radio-frequency signals by the up-conversion module 8 to drive the solid-state power source 2. At the same time, the I / Q signal data of each path of signals are uploaded to the host computer 9 through the data bus.

[0044] Furthermore, a field programmable gate array (referred to as FPGA) is provided in the digital low-level system 1, and a digital signal processing module is provided in the FPGA. The digital signal processing module respectively obtains three groups of original digital baseband signals through I / Q demodulation of the intermediate-frequency signals, that is: the cavity voltage signal of the superconducting cavity V c , the forward voltage signal V f * and the reverse voltage signal V r * , as Figure 2b shown, after the rectangular pulse output from the DAC passes through the radio-frequency loop, a red peak electric field pulse signal is obtained. It should be noted that the voltage signals involved in this embodiment (such as V c , V f * , V r * , V r ,V f (etc.) are in the plural form. They can be expressed in the form of amplitude and phase. For example: V = | V | e j∠V , where | V | is the amplitude or modulus, and ∠ V is the phase or argument; they can also be expressed in the form of real part plus imaginary part. For example: V = V I + jV Q , where V I is the real part or in-phase component, V Q is the imaginary part or quadrature component.

[0045] S3. Forward voltage signal calibration: Calibrate the forward voltage V f * . After calibration, the forward voltage signal V f is obtained. The calibration method is a prior art and will not be elaborated here.

[0046] S4. Calculate the dynamic detuning corresponding to the power source excitation V LLRF : Based on the cavity pressure signal V c and the forward voltage signal V f , establish the cavity differential equation and solve the cavity differential equation to obtain the cavity dynamic detuning Δ V LLRF corresponding to the power source excitation. f .

[0047] In this embodiment, the calculation process of the cavity dynamic detuning Δ f includes: S41. Based on the cavity pressure signal V c and the forward voltage signal V f , establish the cavity differential equation as:

[0048] ; where is the differential of the cavity pressure V c , β is the coupling coefficient of the cavity, ω 0.5 is the half-bandwidth of the cavity, and Δ ωis the detuning of the cavity. ω 0.5 and Δ ω is in radians per second. f 0.5 With Δ f also represents the half-bandwidth and detuning of the cavity, both in hertz. I b is the beam current, r / Q is the geometric factor of the cavity, related to the shape of the superconducting cavity. The corresponding relationships of the above physical quantities are as follows: .

[0049] When measuring the static Lorentz detuning Δ F , it is generally necessary to turn off the beam current first to avoid the influence of the beam loading effect on the measurement. Therefore, the last term of the above differential equation can be deleted. At the same time, to facilitate subsequent formula derivation, define the parameter , then the above differential equation can be further simplified to: .

[0050] S42. Decompose the cavity voltage signal V c and the forward voltage signal V f into real and imaginary parts as: ; Substitute the above formula into the cavity differential equation to get: ; Separate the real and imaginary parts of the above formula, then there are: .

[0051] S43. Solve the above system of linear equations with two variables.

[0052] In this embodiment, regard ω 0.5 and Δ ω as unknowns, regard other physical quantities as coefficients, and solve the above system of linear equations with two variables, then there are: .

[0053] The second equation of the above system of equations is the formula for calculating the dynamic detuning of the cavity. It should be noted that the loaded quality factor Q L can generally reflect the half-bandwidth of the cavity. Figure 3a is the amplitude and phase of the cavity voltage signal V c and the forward voltage signal V f . Figure 3bThe loaded quality factor calculated according to Equation (4) Q L and the detuning Δ f . Usually, due to the initial and ending phases of the pulse, the cavity pressure signal V c has a relatively small value (close to 0). The derivative operations on the real and imaginary parts of the cavity pressure signal in Equation (4) will result in V c large deviations in the calculation results of Q L and Δ f in these two phases. As shown in Figure 3b , before 0.5 ms (initial phase) and after 95 ms (ending phase), the calculation results of the detuning fluctuate up and down.

[0054] S5. Calculate the excitation of the power source V LLRF corresponding static Lorentz Δ F and the steady-state cavity field E .

[0055] In this embodiment, the solution process of the static Lorentz Δ F includes:[[]] S51. Calculate the detuning Δ f of the cavity caused by the helium pressure in f HE .

[0056] In this embodiment, the detuning Δ f is mainly composed of the Lorentz detuning Δ f LFD , the detuning Δ f HE caused by the helium pressure, and the microphonic detuning Δ f micro , that is, Δ f= Δ f LFD +Δ f HE +Δ f micro . Since the helium pressure is a slowly changing physical quantity, within a radio frequency pulse (90 ms), it can be approximately considered that the detuning Δ f HE caused by the helium pressure remains constant, that is, within a single radio frequency pulse, Δ f HE is approximately stable. Δ f HE can be calculated according to the average value of the dynamic detuning Δ f in the initial phase of the pulse, that is ; Among them, the lower integration boundary t a should avoid the initial stage of the pulse to prevent the Δ caused by the derivative operation error f from jittering up and down. As Figure 3b shown, it can be selected that t a is equal to 0.5 milliseconds. The upper boundary of the integration t b can be selected at the moment when the Δ f curve has not shown an obvious downward change trend, Figure 3b in t b it can be selected as 0.8 milliseconds. Finally, Δ f HE is approximately -49.55 kHz.

[0057] S52. Subtract Δ f from the cavity dynamic detuning Δ f HE to obtain a new detuning variable Δ f 2.

[0058] In this embodiment, by subtracting the influence of Δ f from the cavity dynamic detuning Δ f HE a new detuning variable Δ f 2 can be obtained, which mainly consists of the Lorentz detuning Δ f LFD and the microphony detuning Δ f micro i.e., Δ f 2 = Δ f LFD + Δ f micro . Among them, Δ f LFD can also be composed of the static Lorentz detuning Δ F and the dynamic Lorentz detuning σf lfd i.e., Δ f LFD ( t ) = Δ F + σf lfd ( t ). Δ F refers to the average value after Δ f LFD reaches the steady state, and it no longer changes with time. σf lfd refers to Δ f LFDThe component that changes over time. Therefore, Δ f 2 = Δ F + σf lfd ( t )+Δ f micro ( t ). As shown in Figure 5a , the calculated result of Δ f after deducting Δ f HE from the dynamic detuning Δ f 2.

[0059] S53. Calculate the static Lorentz detuning Δ V LLRF under the current power source excitation F i .

[0060] In this embodiment, as shown in Figure 5a , the detuning variable Δ f 2 rapidly decreases in the initial stage of the pulse and no longer has an obvious downward trend after 60 milliseconds. At this time, the dynamic Lorentz detuning σf lfd ( t ) can be approximately ignored. Δ f 2 is mainly composed of the static Lorentz detuning Δ F and the microphony detuning Δ f micro , that is, Δ f 2 = Δ F + Δ f micro . Due to the existence of the microphony detuning Δ f micro , Δ f 2 will still fluctuate periodically up and down. Generally, Δ f micro can be expressed as the superposition of M sine waves with different amplitudes, phases and frequencies, that is: ; where a k , ϕ k and f k respectively correspond to the amplitude, phase and frequency of the k th sine wave. The sine wave is a periodic signal, and its mean value is 0 under integer periods. According to the measured results of microphony on the CAFe device, the main frequency component of microphony is 50 Hz (50 Hz is the industrial power frequency), that is, the amplitude is the largest (a k The frequency corresponding to the sine wave with the maximum (Δ) is 50 Hz; that is, Δ f micro can be approximately regarded as a sine wave of 50 Hz, and its period T m is 20 ms. As Figure 5b shown, take t 1 as a point after 60 ms (Δ f 2 no longer has a downward trend), take t 2 = t 1 + T m ( t 2 ≤ T pw ), there is ; Therefore, at the peak electric field E peak of the current pulse, the static Lorentz detuning Δ i of the F i th pulse can be expressed as: ; That is: ; In the formula, as Figure 5b shown, t 2 is the end time of the pulse (about 90 ms), T m is the period (20 ms) corresponding to the main frequency component of the microphonics (50 Hz), t 1 = t 2 - T m is the starting time of the integral used to calculate the static Lorentz detuning Δ F i of the

[0061] S54. Calculate the steady-state cavity field V LLRF corresponding to the same time period ( t 1 → t 2) under the current power source excitation E i .

[0062] .

[0063] S6. Change the power source excitation and repeat the above measurement process to plot the scatter diagram of (E 2 , ΔF), and linearly fit to determine the Lorentz detuning coefficient KL 。

[0064] In this embodiment, the average steady-state cavity field of multiple RF pulses E and the average static Lorentz detuning Δ F are calculated, and the Lorentz detuning coefficient is obtained by linear fitting K L , including: S61. Keep the power source excitation V LLRF unchanged, and output T rp continuous rectangular pulses with N as the period. Calculate the steady-state cavity field i of the E i th pulse and the static Lorentz detuning Δ F i respectively, and take the average of E i and Δ F i to obtain the average steady-state cavity field E and the average static Lorentz detuning Δ F , obtaining the first group ( E , Δ F ); 。

[0065] In this embodiment, in order to eliminate measurement errors, N should be greater than 20 (selected as 30 in this embodiment, for example only, not limited to this). Since T rp is 1 second, 30 rectangular pulses take a total of 30 seconds.

[0066] S62. Change the power source excitation V LLRF , and re-measure to calculate Δ f , Δ F i , Δ F respectively, obtaining multiple groups ( E , Δ F ).

[0067] In this embodiment, by changing the power source excitation V LLRF , the peak electric field E peak and the corresponding cavity Lorentz detuning are changed. To meet the accuracy of subsequent linear fitting, the low-level system needs to output L groups ( L ≥ 3) of V LLRFFor example, Figure 4 As shown, in this embodiment, 4 groups ( L = 4) of rectangular pulses with different amplitudes are selected. V LLRF Rectangular pulses. V LLRF The value of E peak should not be too large to avoid quenching of the superconducting cavity due to excessive peak electric field. V LLRF The value of

[0068] should not be too small to avoid the Lorentz detuning signal being overwhelmed by measurement noise. In this embodiment, the critical peak electric field of the superconducting cavity is about 32 MV / m, and the maximum peak field strength can be selected as 29 MV / m to ensure a margin of about 10% (29 MV / m ≈ 0.9 × 32 MV / m). The minimum peak field strength can be selected around 0.5 - 0.75 of the maximum peak field strength to ensure a good measurement signal-to-noise ratio. The minimum peak field strength in this embodiment is about 20 MV / m (≈ 0.7 × 29 MV / m). Figure 4 As shown, since each V LLRF corresponds to 30 ( N = 30) rectangular pulses, then L ( L = 4) V LLRF corresponds to 120 rectangular pulses. The time required to output each rectangular pulse is T rp ( T rp = 1 s), so it takes two minutes to complete the measurement, which is much lower than the existing measurement technology (usually greater than 15 minutes).

[0069] Furthermore, Figure 5c plots the corresponding V LLRF against E i 2 and ΔF i as well as E 2 and ΔF. Among them, four different colors represent 4 different V LLRF . For each color, a single point represents the coordinate (E i 2 , ΔF i ), and the circle represents the coordinate (E 2 , ΔF).

[0070] S63, Determining the Lorentz Detuning Coefficient by Linear Fitting K L .

[0071] In this embodiment, the static Lorentz detuning Δ F is proportional to the square of the steady-state cavity field E , that is: ; where K L is the Lorentz detuning coefficient, generally negative, with the unit of [Hz / (MV / m) 2 .

[0072] By linearly fitting Figure 5c the four (E 2 , Δ F ) circles in, the Lorentz detuning coefficient can be determined. The linear fitting process can directly call the numpy.polyfit function in the Python language. As Figure 5b shown, the fitting result of the Lorentz detuning coefficient in this embodiment is 0.153 [Hz / (MV / m) 2 , that is, Δ F= -0.153E 2 . Compared with the traditional manual measurement results shown in Figure 1 , the Lorentz detuning fluctuation of the automated measurement is very small, with higher accuracy and less time consumption.

[0073] The verification process of the automated measurement method for the Lorentz detuning coefficient of the superconducting cavity of the present invention will be described in detail below through specific embodiments.

[0074] The Lorentz detuning coefficient calculated in this embodiment is compared with the Lorentz detuning coefficient obtained by the model identification technology (existing method). Among them, model identification refers to using the greyest function of the Matlab system identification toolbox. As Figure 6a and Figure 6b shown, according to the cavity field waveform and detuning data when the electromechanical oscillation occurs, the transfer function of the entire cavity mechanical mode is identified, and the steady-state value of the transfer function is K L . The magnitude of the steady-state value of the transfer function | K L | is -0.158 [Hz / (MV / m) 2 , and the phase is -180 degrees, that is K L =0.158 e j(180°) =-0.158 [Hz / (MV / m) 2 . It is basically consistent with the measurement results of the present invention, thus further cross-verifying the effectiveness of the present invention.

[0075] Embodiment 2: The above Embodiment 1 provides an automated measurement method for the Lorentz detuning coefficient of a superconducting cavity. Correspondingly, this embodiment provides an automated measurement device for the Lorentz detuning coefficient of a superconducting cavity. The device provided in this embodiment can implement the automated measurement method for the Lorentz detuning coefficient of the superconducting cavity in Embodiment 1, and this device can be implemented in a software, hardware, or a combination of software and hardware manner. For the convenience of description, when describing this embodiment, various units are described separately according to their functions. Of course, in implementation, the functions of each unit can be implemented in the same or multiple software and / or hardware. For example, this device can include integrated or separate functional modules or functional units to execute the corresponding steps in the methods of Embodiment 1. Since the device in this embodiment is basically similar to the method embodiment, the description process of this embodiment is relatively simple, and the relevant parts can refer to the partial description of Embodiment 1. The embodiment of the automated measurement device for the Lorentz detuning coefficient of the superconducting cavity provided by the present invention is only illustrative.

[0076] Specifically, the automated measurement device for the Lorentz detuning coefficient of the superconducting cavity provided by the present invention includes: In a second aspect, the present invention also provides an automated measurement device for the Lorentz detuning coefficient of a superconducting cavity, including: A parameter setting unit, configured to set the power source excitation and pulse parameters based on the electromagnetic characteristics of the superconducting cavity; A signal acquisition unit, configured to perform pulsed field building on the superconducting cavity based on the set pulse parameters, and obtain a cavity voltage signal and a forward voltage signal; A dynamic detuning calculation unit, configured to establish a cavity differential equation based on the cavity voltage signal and the forward voltage signal, and solve the cavity differential equation to obtain the cavity dynamic detuning corresponding to the power source excitation; A static Lorentz calculation unit, configured to calculate the static Lorentz Δ corresponding to the power source excitation based on the cavity dynamic detuning F and the steady-state cavity field E ; A Lorentz detuning coefficient calculation unit, configured to change the power source excitation and repeat the above measurement process to obtain multiple sets of static Lorentz Δ F and the steady-state cavity field E , and plot a scatter plot for linear fitting to obtain the Lorentz detuning coefficient.

[0077] Embodiment 3: This embodiment provides an electronic device corresponding to the automated measurement method for the Lorentz detuning coefficient of the superconducting cavity 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.

[0078] Such as Figure 7As shown, the electronic device includes a processor, a memory, a communication interface, and a bus. The processor, the memory, and the communication interface are connected through the bus to complete communication with each other. The memory stores a computer program that can run on the processor. When the processor runs the computer program, it executes the method of Embodiment 1. The implementation principle and technical effects are similar to those of Embodiment 1 and will not be elaborated here. Those skilled in the art can understand that Figure 7 the structure shown in Figure 7 is only a block diagram of some structures related to the solution of this application, and does not constitute a limitation on the computing device to which the solution of this application is applied. The specific computing device may include more or fewer components than those shown in the figure, or combine some components, or have a different component layout.

[0079] In a preferred embodiment, when the logical instructions in the above-mentioned memory can be implemented in the form of a software functional unit and sold or used as an independent product, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or a part of this technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to enable a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods described in various embodiments of this application. The aforementioned storage medium includes: various media such as USB flash drives, mobile hard disks, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), and optical discs that can store program codes.

[0080] In a preferred embodiment, the processor can be various types of general-purpose processors such as a central processing unit (CPU) and a digital signal processor (DSP), which are not limited here.

[0081] Embodiment 4: This embodiment provides a computer-readable storage medium storing one or more programs. The one or more programs include computer instructions. When the computer instructions are executed by the computer, the computer is caused to execute the method provided in Embodiment 1 above.

[0082] In a preferred embodiment, the computer-readable storage medium can be a tangible device that holds and stores instructions executed. For example, it can be, but is 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 of the above. The computer-readable storage medium stores computer program instructions that cause the computer to execute the method provided in Embodiment 1 above.

[0083] This application is described with reference to the flowcharts and / or block diagrams of methods, apparatus (devices), and computer program products according to embodiments of the present application. It should be understood that each flow and / or block in the flowchart and / or block diagram can be implemented by computer program instructions, as well as the combination of flows and / or blocks in the flowchart and / or block diagram. These computer program instructions can be provided to the processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing devices to generate a machine, such that the instructions executed by the processor of the computer or other programmable data processing devices produce means for implementing the functions specified in one flow Figure 1 or more flows and / or blocks Figure 1 or means for implementing the functions specified in one block or more blocks.

[0084] These computer program instructions can also be stored in a computer-readable memory that can direct a computer or other programmable data processing device to work in a specific manner, such that the instructions stored in the computer-readable memory produce a manufactured article including instruction means that implement the functions specified in one flow Figure 1 or more flows and / or blocks Figure 1 or means for implementing the functions specified in one block or more blocks.

[0085] These computer program instructions can also be loaded onto a computer or other programmable data processing device, such that a series of operation steps are executed on the computer or other programmable device to generate a computer-implemented process, so that the instructions executed on the computer or other programmable device provide steps for implementing the functions specified in one flow Figure 1 or more flows and / or blocks Figure 1 or means for implementing the functions specified in one block or more blocks.

[0086] Each embodiment in this specification is described in a progressive manner. The same or similar parts among the embodiments can be referred to each other, and the differences between each embodiment and other embodiments are emphasized. In the description of this specification, the descriptions with reference to terms such as "a preferred embodiment", "furthermore", "specifically", "in this embodiment", etc. mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the embodiments of this specification. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0087] 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 them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. An automated measurement method for the Lorentz detuning coefficient of a superconducting cavity, characterized in that, The method includes: Setting a power source excitation and pulse parameters based on the electromagnetic characteristics of a superconducting cavity; Performing pulsed field building of the superconducting cavity based on the set pulse parameters, and obtaining a cavity pressure signal and a forward voltage signal; Establishing a cavity differential equation based on the cavity pressure signal and the forward voltage signal, and solving the cavity differential equation to obtain the cavity dynamic detuning corresponding to the power source excitation; Calculate the static Lorentz Δ corresponding to the excitation of the power source based on the dynamic detuning of the cavity F and the steady-state cavity field E ; Repeat the above measurement process by changing the power source excitation to obtain multiple sets of static Lorentz Δ F and the steady-state cavity field E , and plot a scatter plot for linear fitting to obtain the Lorentz detuning coefficient.

2. The automated measurement method for the Lorentz detuning coefficient of a superconducting cavity according to claim 1, characterized in that, The pulse parameters include a pulse width, a repetition period, and a pulse amplitude, wherein the pulse width is significantly greater than the field building time, and the repetition period is greater than the pulse width.

3. The automated measurement method for the Lorentz detuning coefficient of a superconducting cavity according to claim 1, characterized in that Establishing a cavity differential equation based on the cavity pressure signal and the forward voltage signal, and solving the cavity differential equation to obtain the cavity dynamic detuning corresponding to the power source excitation, including: Establishing a cavity differential equation based on the cavity pressure signal and the forward voltage signal; Decomposing the cavity pressure signal and the forward voltage signal according to real and imaginary parts and substituting them into the cavity differential equation to obtain a system of linear equations with real and imaginary parts separated; Solving the system of linear equations to obtain the cavity dynamic detuning.

4. The automated measurement method for the Lorentz detuning coefficient of a superconducting cavity according to claim 3, characterized in that, The calculation formula for the cavity dynamic detuning is: ； Among them, and are the real part and the imaginary part of the cavity pressure signal respectively; and are the real part and the imaginary part of the forward voltage signal respectively, and are the differential real part and the imaginary part of the cavity pressure signal respectively, K is a set parameter, , β is the coupling coefficient of the cavity, ω 0.5 is the half bandwidth of the cavity, Δ ω is the detuning of the cavity, is the dynamic detuning of the cavity.

5. The automated measurement method for the Lorentz detuning coefficient of a superconducting cavity according to claim 4, wherein Calculating the static Lorentz Δ corresponding to the excitation of the power source based on the dynamic detuning of the cavity F and the steady-state cavity field E， including: Calculate the dynamic detuning Δ of the cavity f Detuning Δ caused by the medium helium pressure f HE ; Subtract Δ f from the cavity dynamic detuning Δ f HE to obtain a new detuning variable Δ f 2, where Δ f 2 = Δ F + σf lfd ( t ) + Δ f micro ( t ), where Δ F is the static Lorentz detuning, σf lfd is the dynamic Lorentz detuning, and Δ f micro is the microphonic detuning; Based on the new detuning variable Δ f 2, calculate the static Lorentz detuning Δ i of the F i th pulse under the current power source excitation, and at the same time calculate the steady-state cavity field E i corresponding to the same time period under the current power source excitation.

6. The automatic measurement method for the Lorentz detuning coefficient of a superconducting cavity according to claim 5, wherein Static Lorentz detuning Δ F i and the steady-state cavity field E i are respectively: ； ； Among them, t 2 is the pulse end time, T m is the period corresponding to the main frequency component of the microphonics, t 1 = t 2 - T m is for calculating the static Lorentz detuning Δ F i is the integral start time used, E peak is the peak electric field.

7. The automated measurement method for the Lorentz detuning coefficient of a superconducting cavity according to claim 5, characterized in that Repeat the above measurement process by changing the power source excitation to obtain multiple sets of static Lorentz Δ F and the steady-state cavity field E , and plot a scatter plot for linear fitting to obtain the Lorentz detuning coefficient, including: Keep the current power source excitation unchanged, and T rp output continuous rectangular pulses with a period of N to calculate the steady-state cavity field of the i th pulse and the static Lorentz detuning Δ E i , and average F i and Δ E i to obtain the average steady-state cavity field F i and the average static Lorentz detuning Δ E F to obtain the first group ( E , Δ F );​ Change the power source excitation and repeat the above process for calculation ， Obtain multiple sets of ( E , Δ F ); Due to the static Lorentz detuning Δ F being proportional to the square of the steady-state cavity field E the Lorentz detuning coefficient is determined by linear fitting wherein, K L is the Lorentz detuning coefficient.

8. An automated measuring device for the Lorentz detuning coefficient of a superconducting cavity, characterized in that, including: A parameter setting unit configured to set a power source excitation and pulse parameters based on the electromagnetic characteristics of a superconducting cavity; A signal acquisition unit configured to perform pulsed field building of the superconducting cavity based on the set pulse parameters, and obtain a cavity pressure signal and a forward voltage signal; A dynamic detuning calculation unit configured to establish a cavity differential equation based on the cavity pressure signal and the forward voltage signal, and solve the cavity differential equation to obtain the cavity dynamic detuning corresponding to the power source excitation; A static Lorentz calculation unit, configured to calculate a static Lorentz Δ corresponding to a power source excitation based on a dynamic detuning of a cavity F and a steady-state cavity field E ; The Lorentz detuning coefficient calculation unit is configured to change the power source excitation to repeat the above measurement process, obtain multiple sets of static Lorentz Δ F and the steady-state cavity field E , and plot a scatter plot for linear fitting to obtain the Lorentz detuning coefficient.

9. An electronic device, characterized in that, including: 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 1-7.

10. 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 1-7.

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