Automated measurement method, device, equipment and medium for Lorentz detuning coefficient of superconducting cavity

Abstract

The present invention discloses an automated measurement method, device, equipment and medium for the Lorentz detuning coefficient of a superconducting cavity, comprising: setting power source excitation and pulse parameters based on the electromagnetic characteristics of the superconducting cavity; performing superconducting cavity pulse field building 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, solving the cavity differential equation to obtain the cavity dynamic detuning corresponding to the power source excitation; and calculating the static Lorentz Δ corresponding to the power source excitation based on the cavity dynamic detuning. F and 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 steady-state cavity field E , and a #imgabs0# scatter plot is drawn and linearly fitted to obtain the Lorenz detuning coefficient. Therefore, the present invention can automatically calculate the Lorenz detuning coefficient, greatly improving the measurement efficiency and at the same time surpassing the measurement accuracy of traditional methods.

Description

Technical Field

[0001] The present invention relates to a method, device, equipment and medium for automatically measuring the Lorentz force detune (LFD) coefficient of a superconducting cavity, and relates to the field of particle accelerators. Background Art

[0002] Accelerators play a vital role in fields such as materials science, scientific research, and medicine. Currently, accelerators under construction, such as CiADS, HIAF, and HEPS, have all chosen radio frequency superconducting technology. Superconducting cavities are the core components of superconducting accelerators, primarily used for charged particle acceleration. They offer advantages such as low loss and high gradient, making them suitable for accelerating high-intensity beams in continuous-wave (CW) or long-pulse modes. However, due to their narrow operating bandwidth, typically tens to hundreds of hertz, superconducting cavities are highly susceptible to interference from factors such as Lorentz detuning and helium pressure fluctuations, leading to frequency detuning and subsequent failures, impacting the long-term stable operation of the accelerator.

[0003] LFD refers to the Lorentz force generated by the RF field stimulating currents in the cavity walls. Under the influence of the Lorentz force, the volume of the superconducting cavity undergoes slight deformations, contracting at the cavity neck and expanding near the cavity equator, thereby causing a shift in the superconducting cavity's intrinsic frequency. LFD not only affects the stability of the electromagnetic field in the superconducting cavity and increases the RF power requirement, but in severe cases, it can also trigger electromagnetic-mechanical coupling oscillations in the superconducting cavity, which can easily lead to widespread cavity failure.

[0004] The LFD coefficient is a key parameter for calculating the Lorentz force and measuring the mechanical properties of a cavity. Currently, traditional methods for measuring the LFD coefficient are typically based on the cavity's continuous-wave self-oscillation mode, 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, requiring a significant amount of machine operating time. Furthermore, due to the long measurement time within the same cavity, factors such as helium pressure fluctuations and environmental vibrations can significantly affect measurement accuracy.

[0005] Therefore, how to accurately measure LFD is crucial to ensuring the stable operation of the superconducting cavity. A more accurate automated measurement method is urgently needed to address the shortcomings of existing technologies. Summary of the Invention

[0006] The present invention aims to solve at least one of the technical problems existing in the prior art. To address this problem, the present invention provides a method, device, apparatus, and medium for automated measurement of the Lorentz detuning coefficient of a superconducting cavity, which significantly improves measurement efficiency while achieving superior measurement accuracy to conventional methods.

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

[0008] In a first aspect, the present invention provides a method for automatically measuring the Lorentz detuning coefficient of a superconducting cavity, the method comprising:

[0009] Based on the electromagnetic characteristics of the superconducting cavity, set the power source excitation and pulse parameters;

[0010] Perform superconducting cavity pulse field building based on the set pulse parameters and obtain cavity pressure signal and forward voltage signal;

[0011] A cavity differential equation is established based on the cavity pressure signal and the forward voltage signal, and the cavity dynamic detuning corresponding to the power source excitation is obtained by solving the cavity differential equation.

[0012] Calculate the static Lorentz Δ corresponding to the power source excitation based on the dynamic detuning of the cavity F and steady-state cavity field E ;

[0013] Repeat the above measurement process by changing the power source excitation to obtain multiple sets of static Lorentz Δ F and steady-state cavity field E , and draw The Lorenz detuning coefficient was obtained by linear fitting of the scatter plot.

[0014] In some possible implementations, the pulse parameters include pulse width, repetition period, and pulse amplitude, wherein the pulse width is significantly greater than the field buildup time, and the repetition period is greater than the pulse width.

[0015] In some possible implementations, a cavity differential equation is established based on the cavity pressure signal and the forward voltage signal, and the cavity differential equation is solved to obtain the cavity dynamic detuning corresponding to the power source excitation, including:

[0016] Based on the cavity pressure signal and the forward voltage signal, a cavity differential equation is established;

[0017] The cavity pressure signal and the forward voltage signal are decomposed into real and imaginary parts and then inserted into the cavity differential equation to obtain a two-variable linear equation with real and imaginary parts separated.

[0018] Solving the two-variable linear equation yields the cavity dynamic detuning.

[0019] In some possible implementations, the cavity is dynamically detuned The calculation formula is:

[0020] ;

[0021] in, and Cavity pressure signal V c The real and imaginary parts of and Forward voltage signal V f The real and imaginary parts of and Cavity pressure signal V c The real and imaginary parts of the differential, K For the set parameters, , β is the cavity coupling coefficient, ω 0.5 is the half bandwidth of the cavity, Δ ω is the cavity detuning, It is the dynamic detuning of the cavity.

[0022] In some possible implementations, the static Lorentz Δ corresponding to the power source excitation is calculated based on the cavity dynamic detuning. F and steady-state cavity field E， include:

[0023] Calculate the cavity dynamic detuning Δ f Detuning Δ caused by medium helium pressure f HE ;

[0024] The dynamic detuning of the cavity Δ f Deduct Δ f HE , and obtain the new detuning variable Δ f 2, among which, , where Δ F is the static Lorenz detuning, σf lfd is the dynamic Lorenz detuning, Δ f micro Detuned for microphonics;

[0025] Based on the new detuning variable Δ f 2. Calculate the first i The static Lorentz detuning Δ of the pulses F i , and calculate the steady-state cavity field corresponding to the same time period under the current power source excitation E i .

[0026] In some possible implementations, the static Lorentz detuning Δ F i and steady-state cavity field E i They are:

[0027] ;

[0028] ;

[0029] in, t 2 is the pulse end time, T m is the period corresponding to the main frequency component of the howling noise, t 1= t 2- T m To calculate the static Lorentz detuning Δ F i The integration start time used, E peak is the peak electric field.

[0030] In some possible implementations, the above measurement process is repeated by changing the power source excitation to obtain multiple sets of static Lorentz Δ F and steady-state cavity field E , and draw The scatter plot is linearly fitted to obtain the Lorenz detuning coefficient,

[0031] include:

[0032] Keep the current power source excitation unchanged, T rp Periodic output N continuous rectangular pulses, calculate the i steady-state cavity field of a pulse E i and the static Lorentz detuning Δ F i , and E i and Δ F i The average steady-state cavity field is obtained by taking the average value E and the average static Lorentz detuning Δ F , and get the first group ( E , Δ F );

[0033] Change the power source excitation and repeat the above process to calculate ， Get multiple groups ( E , Δ F );

[0034] Due to the static Lorentz detuning Δ F Steady-state cavity field E Proportional to the square, through linear fitting Determine the Lorenz detuning coefficient, where , K L is the Lorenz detuning coefficient.

[0035] In a second aspect, the present invention further provides an automatic measurement device for the Lorentz detuning coefficient of a superconducting cavity, comprising:

[0036] a parameter setting unit configured to set power source excitation and pulse parameters based on electromagnetic characteristics of the superconducting cavity;

[0037] A signal acquisition unit is configured to perform superconducting cavity pulse field building based on set pulse parameters and obtain a cavity pressure signal and a forward voltage signal;

[0038] 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;

[0039] The static Lorentz calculation unit is configured to calculate the static Lorentz Δ corresponding to the power source excitation based on the dynamic detuning of the cavity. F and steady-state cavity field E ;

[0040] 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 steady-state cavity field E , and draw The Lorenz detuning coefficient was obtained by linear fitting of the scatter plot.

[0041] 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 to enable the processor to execute the described method.

[0042] 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 the method described.

[0043] The present invention adopts the above technical solution, which has the following characteristics:

[0044] 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 traditional methods, greatly improving the measurement efficiency. At the same time, the measurement accuracy is better than that of traditional methods. It can monitor the entire process of dynamic changes in cavity detuning caused by LFD online, laying the foundation for improving the operational stability of superconducting cavities.

[0045] 2. The present invention measures and analyzes the Lorenz detuning coefficient by reading the RF signal under different power source excitations when operating in pulse mode. RF signal acquisition, down-conversion, and IQ demodulation can all be completed by a general digital low-level system, and data processing can be deployed on a general host computer. All of the above applications do not require additional hardware equipment.

[0046] In summary, the present invention can be widely applied to particle accelerators, and is particularly suitable for scenarios of parallel monitoring of multiple cavities in large particle accelerators. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Various other advantages and benefits will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiment below. The accompanying drawings are for illustration purposes only and are not to be considered as limiting the present invention. Throughout the drawings, the same reference numerals are used to denote the same components. In the drawings:

[0048] Figure 1 Schematic diagram of the Lorentz detuning coefficient measured using the existing method.

[0049] Figure 2a This is a flow chart of a method for automatically measuring the Lorentz detuning coefficient of a superconducting cavity according to an embodiment of the present invention.

[0050] Figure 2b This is a system block diagram for online measurement of the Lorentz detuning coefficient of a superconducting cavity according to an embodiment of the present invention.

[0051] Figure 3a Schematic diagram of the cavity pressure, amplitude and phase of the forward signal during pulse operation in an embodiment of the present invention.

[0052] Figure 3b Schematic diagram of cavity loaded quality factor and cavity dynamic detuning obtained based on cavity pressure and forward signal in an embodiment of the present invention.

[0053] Figure 4 Schematic diagram of the principle of measuring static Lorentz detuning in an embodiment of the present invention.

[0054] Figure 5a is the dynamic detuning Δ of the slave cavity in the embodiment of the present invention f Deduct the helium pressure detuning Δ f HE Detuning curve Δ after impact f 2. The red horizontal line is the static Lorentz detuning Δ of a single pulse F .

[0055] Figure 5b is the cavity dynamic detuning Δ measured under different peak electric fields in the embodiment of the present invention f 2 and the corresponding static Lorentz detuning Δ F。

[0056] Figure 5c is the corresponding static Lorentz detuning ΔF and the steady-state cavity field square E in the embodiment of the present invention 2 A scatter plot of .

[0057] Figure 6a The transfer function of the mechanical mode of the cavity obtained by using the existing system identification technology in the embodiment of the present invention is shown.

[0058] Figure 6b In the embodiment of the present invention, the transfer function of the mechanical mode of the entire cavity is obtained based on the cavity field waveform and detuning data when the electromechanical oscillation occurs. The steady-state value of the transfer function is K L .

[0059] Figure 7 FIG. 4 is a structural diagram of an electronic device according to an embodiment of the present invention. DETAILED DESCRIPTION

[0060] It should be understood that the terms used herein are for the purpose of describing specific example embodiments only 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 "comprise", "include", "contain" and "have" are inclusive and therefore specify the presence of stated features, steps, operations, elements and / or parts, but do not exclude the presence 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 to be construed as necessarily requiring them to be performed in the specific order described or illustrated, unless the order of execution is clearly indicated. It should also be understood that additional or alternative steps may be used.

[0061] 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 otherwise, 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.

[0062] 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," "lower," "upper," etc. Such spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures.

[0063] Lorenz detuning coefficient KL Characterizes the mechanical stability of the superconducting cavity, and its absolute value is inversely proportional to the mechanical stability of the cavity. K L The larger the value is, the more significant the frequency detuning of the cavity under the Lorentz force is, and the more unstable the mechanical performance is. K L The influence of the Lorentz force on the cavity frequency can be quantified, and the stability of the superconducting cavity under high power operation can be evaluated. The traditional LFD coefficient measurement method is usually based on the continuous wave self-excitation mode of the cavity, which requires manual adjustment of the cavity excitation amplitude and point-by-point measurement of the corresponding frequency offset. Although this method can measure K L However, there are disadvantages such as low measurement efficiency and long measurement time. In addition, due to the long measurement cycle, factors such as helium pressure fluctuation and environmental vibration will introduce significant errors, which limits the measurement accuracy. Figure 1 As shown, it can be clearly seen that each measurement point is located on both sides of the fitting straight line, with large fluctuations, which affects the measurement accuracy. The present invention provides an automated measurement method, device, equipment and medium for the Lorentz detuning coefficient of a superconducting cavity, comprising: setting the power source excitation and pulse parameters based on the electromagnetic characteristics of the superconducting cavity; performing superconducting cavity pulse field building 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, solving the cavity differential equation to obtain the cavity dynamic detuning corresponding to the power source excitation; and calculating the static Lorentz Δ corresponding to the power source excitation based on the cavity dynamic detuning. F and 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 steady-state cavity field E , and draw The scatter plot is linearly fitted 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.

[0064] Exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although 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. Rather, these embodiments are provided 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.

[0065] Example 1: Figure 2a As shown, the method for automatically measuring the Lorentz detuning coefficient of a superconducting cavity provided in this embodiment includes:

[0066] S1. Set the power source excitation and pulse parameters.

[0067] In this embodiment, because LFD is related to changes in the cavity field, LFD is more likely to occur when the cavity operates in pulsed mode. Furthermore, the separately excited (GDR) mode is more likely to cause electromechanical coupling oscillations in the cavity. Therefore, this embodiment requires the superconducting cavity to operate in self-excited (SEL) mode.

[0068] In this embodiment, the pulse parameters mainly include pulse width T pw , repeat cycle T rp and pulse amplitude. Among them, the pulse width T pw The setting and decay time constant of the superconducting cavity τ Related, τ The size of Q L and ω 0 Joint decision:

[0069] ;

[0070] in, Q L is the loaded quality factor, ω 0 is the resonant angular frequency of the cavity, in radians per second, which is related to the resonant frequency of the cavity f The relationship of 0 is: .

[0071] Furthermore, the cavity field building time T fill Generally should 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 Need to be significantly longer than the site construction time (recommended T pw >10 T fill ), repeat cycle T rp Need to be greater than T pw (suggestion T rp >10 T pw In this embodiment, the resonant frequency of the cavity is 162.5 MHz, and the loaded quality factor is Q L The time constant is approximately τ The pulse width can be set to 1.2 milliseconds T pw The repetition period is 90 milliseconds Trp The time interval is 1 second, which is not limited to this example.

[0072] Furthermore, the power source excitation (ie, low-level output signal) V LLRF Not too big or too small, V LLRF Too large will cause the electric field in the cavity to be too strong, causing the superconducting cavity to quench. V LLRF If it is too small, the Lorentz detuning of the superconducting cavity will be too small and will be drowned out by the noise.

[0073] S2. Baseband signal reading: After the superconducting cavity pulse is established, the cavity pressure signal is obtained V c and the original forward voltage signal V f * .

[0074] In this embodiment, Figure 2b As shown, a system for online measurement of the Lorentz detuning coefficient of a superconducting cavity is also provided, comprising: the output end of a digital low-level system 1 is connected to the input end of a solid-state power source 2; the output end of the solid-state power source 2 is connected to the input end of a directional coupler 3; the through port of the directional coupler 3 is fed into a superconducting cavity 5 via an input coupler 4. The sampling signal of the superconducting cavity 5 P t Feedback to the digital low-level system 1 through the signal extraction coupler 6; the directional coupler 3 collects the cavity incident signal P f and cavity reflection signal P r Feedback to the digital low-level system 1. Each signal ( P t 、 P f 、 P r ) is down-converted by down-conversion module 7 to obtain an intermediate frequency signal, which is received by digital low-level system 1. Digital low-level system 1 demodulates the received intermediate frequency signal to obtain the corresponding digital baseband in-phase and quadrature (I / Q) components. The I / Q components are output by the DAC and restored to the RF signal through up-conversion module 8 to drive solid-state power source 2. Simultaneously, the I / Q signal data of each signal channel is uploaded to the host computer 9 via the data bus.

[0075] Furthermore, the digital low-level system 1 is provided with a field programmable gate array (FPGA), and the FPGA is provided with a digital signal processing module. The digital signal processing module obtains three groups of original digital baseband signals by I / Q demodulation of the intermediate frequency signal, namely: the cavity pressure signal of the superconducting cavity V c, forward voltage signal V f * and reverse voltage signal V r * ,like Figure 2b As shown in FIG, the rectangular pulse output from the DAC passes through the RF loop to obtain a red peak electric field pulse signal. It should be noted that the voltage signal involved in this embodiment (such as V c 、 V f * 、 V r * 、 V r 、 V f 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 + JV Q ,in, V I is the real part or the in-phase component, V Q is the imaginary part or quadrature component.

[0076] S3, forward voltage signal calibration: Forward voltage V f * Perform calibration and obtain the forward voltage signal after calibration V f The calibration method is a prior art and will not be described in detail here.

[0077] S4. Calculate power source excitation V LLRF Corresponding dynamic detuning: based on the cavity pressure signal V c and forward voltage signal V f Establish the cavity differential equation and solve it to obtain the power source excitation V LLRF The corresponding cavity dynamic detuning Δ f .

[0078] In this embodiment, the cavity dynamic detuning Δ f The calculation process includes:

[0079] S41, based on cavity pressure signal V c and forward voltage signal V f The cavity differential equation is established as:

[0080] ;

[0081] in, Cavity pressure V c The differential of β is the cavity coupling coefficient, ω 0.5 is the half bandwidth of the cavity, Δ ω is the detuning of the cavity. ω 0.5 and Δ ω The unit is radians per second. f 0.5 With Δ f It is also used to indicate the half-bandwidth and detuning of the cavity, both in Hertz. I b For beam flow, r / Q is the geometric factor of the cavity, which is related to the shape of the superconducting cavity. The corresponding relationship of the above physical quantities is as follows: .

[0082] When measuring the static Lorentz detuning Δ F When the beam is turned off, it is usually necessary to avoid the influence of beam loading on the measurement. Therefore, the last term of the above differential equation can be deleted. At the same time, in order to facilitate the subsequent derivation of the formula, the parameter is defined as , then the above differential equation can be further simplified as:

[0083] .

[0084] S42, the cavity pressure signal V c and forward voltage signal V f According to the real part and imaginary part, it is decomposed into:

[0085] ;

[0086] Substituting the above formula into the cavity differential equation, we get:

[0087] ;

[0088] Separating the real and imaginary parts of the above formula, we have:

[0089] .

[0090] S43. Solve the above linear equation of two variables.

[0091] In this embodiment, ω 0.5 and Δ ω As an unknown number, and other physical quantities as coefficients, solve the above two-variable linear equation, and we have:

[0092] .

[0093] The second equation in the above equations is the formula for calculating the dynamic detuning of the cavity. It is worth noting that the quality factor is usually Q L It can reflect the half bandwidth of the cavity. Figure 3a Cavity pressure signal V c and forward voltage signal V f Amplitude and phase. Figure 3b is the loaded quality factor calculated according to formula (4) Q L and detuning Δ f Normally, due to the initial and final phases of the pulse, the cavity pressure signal V c The value of is small (close to 0), and the cavity pressure signal in formula (4) is V c The derivative operation of the real and imaginary parts results in Q L and Δ f The calculation results of the two stages have large deviations, such as Figure 3b As shown, the detuning calculation results jump up and down before 0.5 milliseconds (initial stage) and after 95 milliseconds (end stage).

[0094] S5. Calculate power source excitation V LLRF The corresponding static Lorentz Δ F and steady-state cavity field E .

[0095] In this embodiment, the static Lorentz Δ F The solution process includes:

[0096] S51. Calculate the dynamic detuning Δ of the cavity f Detuning Δ caused by medium helium pressure f HE .

[0097] In this embodiment, the detuning Δ fMainly due to the Lorenz detuning Δ f LFD , detuning Δ caused by helium pressure f HE and microphonic detuning Δ f micro It consists of three parts, namely Δ f= Δ f LFD +Δ f HE +Δ f micro Since helium pressure is a slowly changing physical quantity, within a RF pulse (90 milliseconds), the detuning Δ caused by the helium pressure can be approximately considered to be f HE Constant, that is, within a single RF pulse Δ f HE Approximately stable. f HE According to the dynamic detuning Δ f The average value at the initial stage of the pulse is calculated, that is,

[0098] ;

[0099] Among them, the lower boundary of the integral t a The value of needs to avoid the initial stage of the pulse to avoid the error of Δ f Up and down jitter problem. Figure 3b As shown, you can select t a Equal to 0.5 milliseconds. The upper boundary of the integral t b You can choose Δ f When the curve has not yet shown a clear downward trend, Figure 3b middle t b It can be selected as 0.8 milliseconds. Finally, we get Δ f HE About -49.55 kHz.

[0100] S52, in the cavity dynamic detuning Δ f Deduct Δ f HE , and obtain the new detuning variable Δ f 2.

[0101] In this embodiment, the dynamic detuning of the cavity Δ f Deduct Δ f HE The influence of , that is, the new detuning variable Δ f 2, mainly due to the Lorenz detuning Δ fLFD and microphonic detuning Δ f micro It consists of two parts, namely Δ f 2=Δ f LFD +Δ f micro . Among them, Δ f LFD It can be expressed by the static Lorentz detuning Δ F and dynamic Lorenz detuning σf lfd Composition, that is, Δ f LFD ( t ) = Δ F + σf lfd ( t ). Δ F Refers to Δ f LFD The average value after reaching steady state, which no longer changes with time. σf lfd Refers to Δ f LFD The part that changes with time. Therefore, Δ f 2 = Δ F + σf lfd ( t )+Δ f micro ( t ).like Figure 5a Shown is the dynamic detuning Δ f After deducting Δ f HE After Δ f 2 calculation results.

[0102] S53, calculate the current power source excitation V LLRF The static Lorentz detuning Δ F i .

[0103] In this embodiment, Figure 5a As shown, the detuning variable Δ f 2 decreases rapidly at the initial stage of the pulse, and there is no obvious downward trend after 60 milliseconds. At this time, the dynamic Lorenz detuning σf lfd ( t ) can be approximately ignored, Δ f 2 Mainly due to the static Lorentz detuning Δ F and microphonic detuning Δ f microIt consists of two parts, namely Δ f 2=Δ F +Δ f micro Due to the microphonic detuning Δ f micro The existence of Δ f 2 will still fluctuate periodically. f micro It can be expressed as M The superposition of sine waves of different amplitudes, phases and frequencies, that is:

[0104] ;

[0105] in, a k , ϕ k and f k Corresponding to the k The amplitude, phase, and frequency of a sine wave. A sine wave is a periodic signal, and its mean value is 0 in integer cycles. According to the actual measurement results of howling noise on the CAFe device, the main frequency component of the howling noise is 50 Hz (50 Hz is the industrial power frequency), that is, the amplitude is the largest ( a k The frequency of the sine wave with a maximum value is 50 Hz; that is, Δ f micro It can be approximated as a 50 Hz sine wave, with a period of T m is 20 milliseconds. Figure 5b As shown, take t 1 is a point 60 milliseconds later (Δ f 2 no longer has a downward trend), take t 2= t 1+ T m ( t 2≤ T pw ),have

[0106] ;

[0107] Therefore, at the peak electric field of the current pulse E peak Next, i The static Lorentz detuning Δ of the pulses F i It can be expressed as:

[0108] ;

[0109] Right now:

[0110] ;

[0111] In the formula, Figure 5b As shown, t 2 is the pulse end time (about 90 milliseconds), T m is the period (20 milliseconds) corresponding to the main frequency component of the howling noise (50 Hz), t 1= t 2- T m To calculate the static Lorentz detuning Δ F i The integration start time to use.

[0112] S54, calculate the current power source excitation V LLRF In the same time period ( t 1→ t 2) Corresponding steady-state cavity field E i .

[0113] .

[0114] S6. Repeat the above measurement process by changing the power source excitation and plot (E 2 , ΔF) scatter plot, linear fitting to determine the Lorenz detuning coefficient K L .

[0115] In this embodiment, the average steady-state cavity field of multiple RF pulses is calculated. E and the average static Lorentz detuning Δ F , and linear fitting is used to obtain the Lorentz detuning coefficient K L ,include:

[0116] S61, maintain power source excitation V LLRF unchanged, with T rp Periodic output N continuous rectangular pulses, calculate the i steady-state cavity field of a pulse E i and the static Lorentz detuning Δ F i , and E i and Δ F i The average steady-state cavity field is obtained by taking the average value E and the average static Lorentz detuning Δ F , and get the first group (E , Δ F );

[0117] .

[0118] In this embodiment, in order to eliminate the measurement error, N The value of must be greater than 20 (30 is selected in this embodiment, which is an example and not limited to this), because T rp If 1 second is used, then 30 rectangular pulses take a total of 30 seconds.

[0119] S62, change power source excitation V LLRF , re-measure and calculate Δ f , Δ F i , Δ F , and get multiple groups ( E , Δ F ).

[0120] In this embodiment, by changing the power source excitation V LLRF , changing the peak electric field E peak And the corresponding cavity Lorentz detuning. In order to meet the accuracy of subsequent linear fitting, the low-level system needs to output L Group( L ≥ 3) Different amplitudes V LLRF .like Figure 4 As shown, this embodiment selects 4 groups ( L = 4) Different amplitudes V LLRF Rectangular pulse. V LLRF The value of cannot be too large to avoid the superconducting cavity from E peak Too big and lose the advantage. V LLRF The value of must also be kept small to prevent the Lorentz detuning signal from being too small and obscured by measurement noise. In this embodiment, the critical peak electric field of the superconducting cavity is approximately 32 megavolts per meter. The maximum peak electric field strength can be selected to be 29 megavolts per meter to ensure a margin of approximately 10% (29 megavolts per meter ≈ 0.9 × 32 megavolts per meter). The minimum peak electric field strength can be selected to be approximately 0.5–0.75 of the maximum peak electric field strength to ensure a good measurement signal-to-noise ratio. In this embodiment, the minimum peak electric field strength is approximately 20 megavolts per meter (≈ 0.7 × 29 megavolts per meter).

[0121] like Figure 4 As shown, since each V LLRFCorresponding to 30 ( N =30) rectangular pulses, then L ( L =4) V LLRF Corresponding to 120 rectangular pulses. The time required to output each rectangular pulse is T rp ( T rp = 1 second), the measurement takes two minutes to complete, which is much faster than existing measurement technologies (usually more than 15 minutes).

[0122] Furthermore, Figure 5c Draw each V LLRF The corresponding pair E i 2 and ΔF i and E 2 And ΔF. Among them, the four different colors represent 4 different V LLRF , for each color, a single point represents the coordinates (E i 2 , ΔF i ), the circle represents the coordinate (E 2 , ΔF).

[0123] S63, linear fitting to determine the Lorenz detuning coefficient K L .

[0124] In this embodiment, the static Lorenz detuning Δ F Steady-state cavity field E Proportional to the square, that is:

[0125] ;

[0126] in, K L is the Lorentz detuning coefficient, which is usually a negative number and its unit is [Hz / (MV / m) 2 ].

[0127] By linear fitting Figure 5c Four of the (E 2 , Δ F ) circle to determine the Lorenz detuning coefficient, and the linear fitting process can directly call the numpy.polyfit function of the Python language. Figure 5b As 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 2Compared to Figure 1 The traditional manual measurement results shown in the figure show that the automated measurement has very small Lorentz detuning fluctuations, higher accuracy, and is less time-consuming.

[0128] The verification process of the method for automatically measuring the Lorentz detuning coefficient of a superconducting cavity according to the present invention is described in detail below through specific embodiments.

[0129] The Lorenz detuning coefficient calculated in this embodiment is compared with the Lorenz detuning coefficient obtained by the model identification technology (existing method), wherein the model identification refers to the use of the greyest function of the Matlab system identification toolbox, such as Figure 6a and Figure 6b As shown, the transfer function of the mechanical mode of the entire cavity is obtained based on the cavity field waveform and detuning data when electromechanical oscillation occurs. The steady-state value of the transfer function is K L . Steady-state magnitude of the transfer function | K L =-0.158 [Hz / (MV / m)] 2 ], the phase is -180 degrees, that is K L =0.158 e j(180°) =-0.158[Hz / (MV / m) 2 ], which is basically consistent with the measurement results of the present invention, thereby further cross-verifying the effectiveness of the present invention.

[0130] Example 2: The above-mentioned Example 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 a superconducting cavity in Example 1, and the device can be implemented by software, hardware, or a combination of software and hardware. For the convenience of description, this embodiment is described by dividing the functions into various units and describing them separately. Of course, the functions of each unit can be implemented in the same or multiple software and / or hardware during implementation. For example, the device may include integrated or separate functional modules or functional units to perform the corresponding steps in each method of Example 1. Since the device of 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 Example 1. The embodiment of the automated measurement device for the Lorentz detuning coefficient of a superconducting cavity provided by the present invention is merely illustrative.

[0131] Specifically, the present invention provides an automatic measurement device for the Lorentz detuning coefficient of a superconducting cavity, comprising:

[0132] In a second aspect, the present invention further provides an automatic measurement device for the Lorentz detuning coefficient of a superconducting cavity, comprising:

[0133] a parameter setting unit configured to set power source excitation and pulse parameters based on electromagnetic characteristics of the superconducting cavity;

[0134] A signal acquisition unit is configured to perform superconducting cavity pulse field building based on set pulse parameters and obtain a cavity pressure signal and a forward voltage signal;

[0135] 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;

[0136] The static Lorentz calculation unit is configured to calculate the static Lorentz Δ corresponding to the power source excitation based on the dynamic detuning of the cavity. F and steady-state cavity field E ;

[0137] 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 steady-state cavity field E , and draw The Lorenz detuning coefficient was obtained by linear fitting of the scatter plot.

[0138] Example 3: This example provides an electronic device corresponding to the automated measurement method for the Lorentz detuning coefficient of a superconducting cavity provided in Example 1. The electronic device may 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 Example 1.

[0139] like Figure 7 As 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 via the bus to complete communication between them. 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. Its implementation principle and technical effect are similar to those of embodiment 1 and will not be repeated here. Those skilled in the art will understand that Figure 7 The structure shown in the figure is only a block diagram of a part of the structure related to the solution of the present application, and does not constitute a limitation on the computing device to which the solution 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 component arrangement.

[0140] In a preferred embodiment, the logic instructions in the aforementioned memory can be implemented in the form of a software functional unit and, when sold or used as an independent product, can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application, or the portion that contributes to the prior art, or the portion of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes several instructions for enabling 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 various media that can store program code, such as a USB flash drive, a mobile hard drive, a read-only memory (ROM), a random access memory (RAM), and an optical disk.

[0141] In a preferred embodiment, the processor may be a central processing unit (CPU), a digital signal processor (DSP), or other general-purpose processors, which are not limited herein.

[0142] 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 embodiment 1.

[0143] In a preferred embodiment, a computer-readable storage medium may be a tangible device that retains and stores instructions executed by the computer, 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 a computer to execute the method provided in the first embodiment.

[0144] 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 produce 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.

[0145] These computer program instructions may 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, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0146] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 The steps for the function specified in one or more boxes.

[0147] Each embodiment in this specification is described in a progressive manner, and the same or 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 reference terms "a preferred embodiment", "further", "specifically", "in the present embodiment", etc. mean 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 a suitable manner in any one or more embodiments or examples. In addition, 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, unless they are contradictory.

[0148] 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 various embodiments of the present invention.

Claims

1. A method for automatically measuring the Lorentz detuning coefficient of a superconducting cavity, characterized in that: The method includes: Based on the electromagnetic characteristics of the superconducting cavity, set the power source excitation and pulse parameters; Perform superconducting cavity pulse field building based on the set pulse parameters and obtain cavity pressure signal and forward voltage signal; A cavity differential equation is established based on the cavity pressure signal and the forward voltage signal, and the cavity dynamic detuning corresponding to the power source excitation is obtained by solving the cavity differential equation. Calculate the static Lorentz Δ corresponding to the power source excitation based on the dynamic detuning of the cavity F and steady-state cavity field E , specifically: Calculate the cavity dynamic detuning Δ f Detuning Δ caused by medium helium pressure f HE ; The dynamic detuning of the cavity Δ f Deduct Δ f HE , and obtain the 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 Lorenz detuning, σf lfd is the dynamic Lorenz detuning, Δ f micro Detuned for microphonics; Based on the new detuning variable Δ f 2. Calculate the first i The static Lorentz detuning Δ of the pulses F i , and calculate the steady-state cavity field corresponding to the same time period under the current power source excitation E i ; Repeat the above measurement process by changing the power source excitation to obtain multiple sets of static Lorentz Δ F and steady-state cavity field E , and draw The Lorenz detuning coefficient was obtained by linear fitting of the scatter plot.

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

3. The method for automatically measuring the Lorentz detuning coefficient of a superconducting cavity according to claim 1, characterized in that: The cavity differential equation is established based on the cavity pressure signal and the forward voltage signal. The cavity differential equation is solved to obtain the cavity dynamic detuning corresponding to the power source excitation, including: Based on the cavity pressure signal and the forward voltage signal, a cavity differential equation is established; The cavity pressure signal and the forward voltage signal are decomposed into real and imaginary parts and then inserted into the cavity differential equation to obtain a two-variable linear equation with real and imaginary parts separated. Solving the two-variable linear equation yields the cavity dynamic detuning.

4. The method for automatically measuring the Lorentz detuning coefficient of a superconducting cavity according to claim 3, characterized in that: The calculation formula of cavity dynamic detuning is: ； in, and Cavity pressure signal V c The real and imaginary parts of and Forward voltage signal V f The real and imaginary parts of and Cavity pressure signal V c The real and imaginary parts of the differential, K For the set parameters, , β is the cavity coupling coefficient, ω 0.5 is the half bandwidth of the cavity, Δ ω is the cavity detuning, It is the dynamic detuning of the cavity.

5. The method for automatically measuring the Lorentz detuning coefficient of a superconducting cavity according to claim 4, characterized in that: Static Lorentz detuning Δ F i and steady-state cavity field E i They are: ； ； in, t 2 is the pulse end time, T m is the period corresponding to the main frequency component of the howling noise, t 1= t 2- T m To calculate the static Lorentz detuning Δ F i The integration start time used, E peak is the peak electric field.

6. The method for automatically measuring the Lorentz detuning coefficient of a superconducting cavity according to claim 4, characterized in that: Repeat the above measurement process by changing the power source excitation to obtain multiple sets of static Lorentz Δ F and steady-state cavity field E , and draw The scatter plot is linearly fitted to obtain the Lorenz detuning coefficient, including: Keep the current power source excitation unchanged, T rp Periodic output N continuous rectangular pulses, calculate the i steady-state cavity field of a pulse E i and the static Lorentz detuning Δ F i , and E i and Δ F i The average steady-state cavity field is obtained by taking the average value E and the average static Lorentz detuning Δ F , and get the first group ( E , Δ F ); Change the power source excitation and repeat the above process to calculate ， Get multiple groups ( E , Δ F ); Due to the static Lorentz detuning Δ F Steady-state cavity field E Proportional to the square, through linear fitting Determine the Lorenz detuning coefficient, where , K L is the Lorenz detuning coefficient.

7. An automatic measurement device for the Lorentz detuning coefficient of a superconducting cavity, characterized in that: include: a parameter setting unit configured to set power source excitation and pulse parameters based on electromagnetic characteristics of the superconducting cavity; A signal acquisition unit is configured to perform superconducting cavity pulse field building based on 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; The static Lorentz calculation unit is configured to calculate the static Lorentz Δ corresponding to the power source excitation based on the dynamic detuning of the cavity. F and steady-state cavity field E , specifically: Calculate the cavity dynamic detuning Δ f Detuning Δ caused by medium helium pressure f HE ; The dynamic detuning of the cavity Δ f Deduct Δ f HE , and obtain the 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 Lorenz detuning, σf lfd is the dynamic Lorenz detuning, Δ f micro Detuned for microphonics; Based on the new detuning variable Δ f 2. Calculate the first i The static Lorentz detuning Δ of the pulses F i , and calculate the steady-state cavity field corresponding to the same time period under the current power source excitation E i ; 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 steady-state cavity field E , and draw The Lorenz detuning coefficient was obtained by linear fitting of the scatter plot.

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 to enable the processor to perform 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 to 6.

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