Tokamak plasma feedback control system and method based on real-time calculation of helium-deuterium ratio

Abstract

The invention discloses a Tokamak plasma feedback control system and method based on real-time calculation of a helium-deuterium ratio, and the system consists of an automatic spectrum collection module, a real-time calculation module of the helium-deuterium ratio, and a data transmission and feedback control module. And continuous framing acquisition of emission spectrum signals including helium spectral lines and deuterium spectral lines in the whole discharge process is realized. And a helium-deuterium ratio real-time calculation algorithm is embedded, smooth filtering, baseline correction and numerical integration are carried out on a preset helium and deuterium characteristic spectral line narrow wavelength window in each frame of spectrum, corresponding spectral line integration intensity is obtained, and the He / (He + D) fuel component ratio is calculated on line. A calculation result is read by a plasma control system and then input into a PID controller, the opening degree of a helium and deuterium inflation valve is automatically adjusted, closed-loop control over the boundary helium and deuterium ratio in the discharging process is achieved, and energy constraint deterioration and fusion performance reduction caused by too high He / D are restrained.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of tokamak plasma control in nuclear fusion experiment, and particularly relates to a tokamak plasma feedback control system and method based on real-time calculation of helium-deuterium ratio. BACKGROUND

[0002] Fusion energy is a potential method of generating electricity using the heat released by nuclear fusion reactions. In fusion, two light atomic nuclei combine to form a heavier nucleus and release energy. The device that uses this process is called a fusion reactor. The ordinary small and medium-sized tokamak discharge experiment uses deuterium, helium and other plasmas to simulate the deuterium-tritium plasma discharge process, one of the core researches is the accurate control of the plasma. The helium-deuterium ratio in the plasma is one of the key parameters affecting the efficiency of nuclear fusion reaction. Traditional helium-deuterium ratio measurement and calculation usually analyzes the original spectrum offline after the discharge ends, which cannot realize real-time control, resulting in fluctuations and uncertainties of the plasma state.

[0003] In high-parameter deuterium plasma, the addition of a certain proportion of helium will have a significant adverse effect on plasma confinement performance and neutron production level. Taking a typical baseline D-H mode discharge as an example, when the volume fraction of helium in the plasma is increased from nearly 0 to about 10% to 15%, the total energy storage and energy confinement time of the plasma decrease significantly, and the beam-target neutron production rate also decreases significantly. The relevant transport analysis results show that this performance degradation is not only caused by the dilution of fuel by helium, but also by the introduction of a small amount of helium, which changes the edge density and temperature step structure, enhances the energy deposition and decay of neutral beams in the high-density boundary region, and thus weakens the effective ion heating in the plasma core and exacerbates the turbulent transport, forming a superimposed adverse effect on energy confinement and fusion power. Therefore, it is difficult to fully explain the above phenomena based on the fuel dilution effect alone. Therefore, for tokamak devices running mainly with deuterium fuel, real-time monitoring and effective control of the helium content and its ratio to deuterium during the discharge process are needed to avoid excessive He / D ratio leading to device performance degradation, which has become an important technical problem to be solved in the future fusion reactor fuel cycle and plasma control design.

[0004] There are still obvious deficiencies in real-time and accuracy of the helium-deuterium diagnostic system in the existing tokamak device. Generally, the original spectrum of the helium-deuterium mixture in the boundary region can only be obtained after the plasma discharge, and the He / D ratio during the discharge is obtained by offline fitting and inversion calculation, which is difficult to reflect the rapid evolution of He / D ratio during the discharge process in time, and cannot meet the needs of online monitoring and feedback control of the boundary He / D ratio in the magnetic confinement nuclear fusion device. Therefore, based on the hardware characteristics and high-speed data interface of the high-performance helium-deuterium measurement spectrometer, a feedback control system capable of calculating the He / D ratio in real time during the discharge process and sending the calculation results directly to the plasma control system is constructed, which not only has obvious engineering implementability, but also has important theoretical significance and practical application value for realizing the accurate regulation of He / D ratio in the tokamak device, optimizing energy confinement and fusion performance. SUMMARY

[0005] The present application aims to solve the technical defects that the existing helium-deuterium ratio measurement mainly relies on offline processing after discharge and cannot directly participate in real-time control during the discharge process, and proposes a plasma feedback control system and method based on real-time calculation of helium-deuterium ratio, which is used for realizing online diagnosis and closed-loop control of tokamak plasma fuel components. The system of the present application takes high-resolution Avantes spectrometer as the core diagnostic means, automatically collects emission spectrum data containing helium spectral line and deuterium spectral line during the plasma discharge process, and obtains spectral information under different information channels through multi-channel synchronous measurement. The collection is driven by a special control program based on MATLAB graphical interface, which realizes automatic addressing, initialization, trigger mode configuration, integration time and measurement time setting of the spectrometer, and continuous, frame sampling of the whole discharge process according to the preset parameters.

[0006] On the data processing and diagnosis side, the present application immediately calls the embedded helium-deuterium ratio calculation algorithm after each frame of spectrum collection is completed, performs smoothing filtering, baseline correction and numerical integration on the target wavelength interval containing helium line and deuterium line, obtains the He / (He+D) fuel ratio diagnostic quantity at the current time, so as to realize online, frame-by-frame calculation of helium-deuterium ratio. The calculation results are output in real time in a unified format through a shared file or an inter-process communication interface, providing continuous fuel component feedback signals for the control system, which can be directly used to adjust the helium, deuterium gas flow, injection power, etc., and constitutes a closed-loop control link of the plasma fuel ratio.

[0007] Furthermore, the application introduces a UDP-based command and trigger mechanism in the control flow, and the discharge control system can issue the measurement configuration information (including file identification, measurement duration, etc.) of this discharge through network messages, and the spectrum measurement and calculation program automatically completes the spectrum collection, real-time calculation of the helium-deuterium ratio, and data archiving and storage during this discharge after receiving the instructions, thereby realizing close coupling with the tokamak discharge sequence. Through the above system and method, the application extends the spectrum helium-deuterium ratio diagnosis from traditional offline analysis to real-time feedback quantity that can directly participate in the discharge process control, thereby improving the timeliness and accuracy of fuel component control and providing a new technical means for advanced fuel ratio control and plasma operation optimization. The specific technical scheme is as follows:

[0008] A tokamak plasma feedback control system based on real-time calculation of the helium-deuterium ratio, comprising a spectrum automatic acquisition module, a helium-deuterium ratio real-time calculation module, and a data transmission and feedback control module.

[0009] The spectrum automatic acquisition module is used to acquire emission spectrum data of helium characteristic spectral lines and deuterium characteristic spectral lines through a spectrum diagnostic system arranged at a plasma boundary divertor and a multi-channel high-resolution fiber spectrometer during the discharge process of a tokamak device.

[0010] The helium-deuterium ratio real-time calculation module is connected with the spectrum automatic acquisition module, is used to pre-process the emission spectrum data, and is used to calculate the spectral line integral intensity in a preset helium spectral line wavelength window and a deuterium spectral line wavelength window in each sampling period, and calculate the current helium-deuterium ratio diagnostic quantity He / (He+D) according to a weighting coefficient.

[0011] The data transmission and feedback control module comprises a reflective memory network interface and a plasma control system (PCS), the reflective memory network interface is used to transmit the helium-deuterium ratio diagnostic quantity to the plasma control system in a shared memory mode in real time, and the plasma control system generates a gas filling control command according to the deviation between the received helium-deuterium ratio diagnostic quantity and a preset target value and issues the control command to a gas filling system, so as to realize closed-loop control of the fuel component of the tokamak plasma.

[0012] Preferably, the spectrum automatic acquisition module comprises:

[0013] An imaging lens and a focusing optical element arranged outside the vacuum chamber of the tokamak are used to focus the plasma emission light of the divertor region or the boundary region to the end face of the fiber array; a plurality of quartz multimode optical fibers are used to transmit the emission light to the multi-channel high-resolution fiber spectrometer; the wavelength coverage range of the fiber spectrometer is 400-900 nm, and at least includes an observation channel covering the He spectral line 468.6 nm and the Dα spectral line 656.3 nm.

[0014] Preferably, the helium-to-deuterium ratio real-time calculation module comprises a spectrum acquisition and processing program running on the control computer, which realizes the following functions through the spectrometer drive interface: automatic addressing and initialization of the spectrometer, setting the integration time, the number of averages and the trigger mode, continuous frame-by-frame acquisition during the tokamak discharge process; after each frame of data acquisition is completed, the first key observation window containing the He 468.6 nm spectral line and the second key observation window containing the Dα 656.3 nm spectral line are extracted, the spectral intensity in the window is filtered and denoised and the baseline is deducted, and the numerical integration method is used to obtain the helium spectral line integral intensity and the deuterium spectral line integral intensity .

[0015] Preferably, the helium-to-deuterium ratio real-time calculation module calculates the helium-to-deuterium ratio according to the following formula:

[0016] ;

[0017] wherein, and are the weighting coefficients determined according to the collision-radiation model photon emission coefficient and experimental calibration results, respectively representing the comprehensive response sensitivity of the optical system and the detector to the helium spectral line and the deuterium spectral line.

[0018] Preferably, the weighting coefficients and are obtained by the following steps: based on the photon emission coefficients of He 468.6 nm and Dα 656.3 nm spectral lines in the ADAS database, the theoretical intensity ratio is calculated within the typical electron temperature and electron density range of the tokamak boundary; historical experimental data of multiple shots with known helium-to-deuterium filling ratio are selected, the optical path transmittance and the detector quantum efficiency are jointly calibrated using the theoretical intensity ratio, and a set of and is obtained by least squares fitting to minimize the deviation of the real-time calculation result from the reference helium-to-deuterium ratio.

[0019] Preferably, in the data transmission and feedback control module, the reflective memory network adopts a PCIe bus structure, and each node is configured with a reflective memory card; the control computer writes the helium-to-deuterium ratio obtained by real-time calculation in the form of a data frame into the local reflective memory, and the plasma control system reads the helium-to-deuterium ratio data from the corresponding address within the control period to realize microsecond-level data synchronization between multiple nodes.

[0020] Preferably, the plasma control system is built-in with a PID controller, which takes the helium-to-deuterium ratio diagnostic quantity as the controlled variable and the preset helium-to-deuterium ratio target value as the set value, calculates the control voltage or opening degree command of the filling valve according to the difference between the two, and optionally superimposes a feedforward command to compensate for the baseline gas injection.

[0021] The application provides a tokamak plasma feedback control method based on real-time calculation of a helium-deuterium ratio, comprising the following steps:

[0022] Step 1, establishing a plasma discharge spectrum diagnosis and data acquisition platform, arranging a spectrum diagnosis system at a boundary field of view of a tokamak device, connecting optical fibers to a multi-channel high-resolution fiber spectrometer, configuring an observation channel containing a target waveband of helium spectrum lines and deuterium spectrum lines, and continuously acquiring frame-by-frame during a whole discharge process;

[0023] Step 2, in each sampling period, performing noise filtering and baseline correction on spectrum data output by the observation channel, performing numerical integration in a preset helium spectrum line and deuterium spectrum line wavelength window, and calculating a He / (He+D) helium-deuterium ratio in real time according to a preset weighting coefficient;

[0024] Step 3, transmitting the helium-deuterium ratio diagnostic quantity obtained in step 2 to a plasma control system in real time through a reflective memory network;

[0025] Step 4, the plasma control system running a feedback control algorithm according to a control error between the helium-deuterium ratio diagnostic quantity and a target value, generating a control command of a helium and / or deuterium gas filling valve, and driving a filling system to execute, so as to realize online adjustment of a boundary helium-deuterium ratio during a tokamak discharge process.

[0026] Preferably, the noise filtering in step 2 adopts Savitzky-Golay smoothing filtering or median filtering, and the baseline correction adopts a moving window minimum value or a polynomial fitting method, so as to suppress the influence of rapid noise fluctuation and continuous spectrum background on the spectrum line integration result.

[0027] Preferably, a multi-shot representative discharge is selected on the tokamak device to perform online calculation and comparison verification of offline complete collision-radiation calculation results, when an average relative error of the real-time diagnostic helium-deuterium ratio in a discharge flat-top stage is less than a preset threshold, corresponding integration windows and weighting coefficients are combined as running parameters and solidified, and are used for regular feedback control in subsequent long-pulse discharge experiments.

[0028] In order to achieve the above object, the application adopts the following technical scheme:

[0029] The application has the following beneficial effects:

[0030] Compared with the traditional off-line spectrum post-processing scheme based on hydrogen-deuterium ratio, the application integrates the real-time spectrum processing by Avantes high-resolution spectrometer and MATLAB, the calculation of helium-deuterium ratio and the high-speed shared PCIE reflection memory, and upgrades the helium-deuterium ratio diagnosis from post-event analysis to real-time feedback quantity directly participating in the discharge process control, thereby realizing the on-line detection and closed-loop control of the tokamak fuel components. The application completes the calculation of helium-deuterium ratio frame by frame in the spectrum collection cycle, and sends it into the plasma control system through the reflection memory with extremely low time delay, thereby greatly improving the response speed and precision of the fuel component control.

[0031] Through the multi-channel Avantes spectrometer and unified triggering, the multi-view and multi-band synchronous diagnosis is realized, and the reliability of the spectrum line integration and fuel ratio estimation is significantly enhanced. Meanwhile, the Savitzky-Golay smoothing and moving window baseline correction and other digital processing methods are introduced, the interference of strong background radiation and noise on the spectrum line appearance and peak area is effectively suppressed, and the more stable and reliable helium-deuterium ratio result is obtained. The integrated software based on MATLAB GUI further simplifies the device management and parameter configuration, realizes the automatic spectrum collection, on-line calculation and visual display, facilitates the user to monitor the real-time curve and replay the historical data, improves the overall efficiency of the experiment operation and physical research, and provides reliable technical support for the fuel optimization control of the high-power and long-pulse tokamak device. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 The overall architecture of the plasma feedback control system based on the real-time calculation of helium-deuterium ratio of the application.

[0033] Fig. 2(a) is the time evolution curve of helium-deuterium ratio calculated by using the traditional off-line physical analysis program;

[0034] Fig. 2(b) is the time evolution curve of helium-deuterium ratio calculated and uploaded by using the real-time on-line diagnosis system of the application;

[0035] Figure 3 Fig. 3 is the experimental waveform diagram of the plasma fuel component feedback control by using the real-time helium-deuterium ratio diagnosis system of the application. DETAILED DESCRIPTION

[0036] In order to make the purpose, technical scheme and advantages of the application more clear, the application is further described in detail below in combination with the drawings and examples. It should be understood that the specific examples described herein are only used to explain the application, and are not used to limit the application. In addition, the technical features involved in each embodiment of the application described below can be combined with each other as long as they do not conflict with each other. In order to achieve the above purpose, the application adopts the following technical scheme.

[0037] As Figure 1As shown, the application provides a plasma feedback control system based on real-time calculation of helium deuterium ratio. The left side is the Tokamak vacuum chamber and the optical acquisition system at the window. The plasma radiation is introduced to the right side spectrum diagnostic device through the optical fiber to obtain He and D spectrum signals. The dashed box is the real-time feedback control part based on RFM network: the control PC drives the Avantes spectrometer to collect the spectrum and calculates the He / (He+D) helium deuterium ratio in MATLAB in real time. The calculation result is written into the RFM shared memory through the PCIe reflection memory card installed in the control PC. The PCS node accesses the RFM network through the optical fiber, reads the helium deuterium ratio diagnostic quantity in real time, and outputs the charging and other execution signals to return to the Tokamak, realizing the closed-loop control of the fuel component based on the helium deuterium ratio. The dashed box represents the low-latency RFM data channel between the diagnostic calculation end and the PCS control end, which is the core of the helium deuterium ratio real-time transmission system of the application. The whole includes: spectrum automatic acquisition module, helium deuterium ratio real-time calculation module and data transmission and feedback control module.

[0038] Spectrum automatic acquisition module: This module includes a Tokamak device (such as EAST), a fiber array arranged in the filter field of view, and a high-resolution Avantes spectrometer. During plasma discharge, the emission light in the boundary region is coupled into the optical fiber through the vacuum window and the imaging optical system, and the output end of the optical fiber is connected to the Avantes spectrometer, realizing automatic acquisition of plasma emission spectrum.

[0039] Helium deuterium ratio real-time calculation module: This module runs on the control PC connected to the Avantes spectrometer through USB. The core software is the host computer program (AvsMeasure) based on MATLAB GUI. The program completes spectrometer initialization, parameter setting, trigger control and data reading through Avantes official drive interface function, and on this basis, embeds the real-time calculation algorithm of helium deuterium ratio, and converts each frame of spectrum data into a time sequence of He / (He+D) ratio.

[0040] Data transmission and feedback control module: This module is composed of a PCIe reflection memory card (RFM) installed in the control PC and a plasma control system PCS. The control PC writes the helium deuterium ratio result calculated in real time into the shared memory through the RFM, and the PCS reads this diagnostic signal on the same RFM network with millisecond-level period, and calculates the helium charging instruction combined with the internal PID controller, and sends it to the charging system through the optical fiber link, realizing the closed-loop control of the helium gas filling valve.

[0041] The application provides a tokamak plasma helium-deuterium ratio real-time online diagnosis and feedback control method based on spectrum diagnosis and atomic physics model combination. The method realizes real-time accurate calculation of the helium (He) and deuterium (D) ratio in the plasma by high time resolution spectrum acquisition, coefficient calibration based on the physical model and fast spectrum data processing algorithm, and applies the helium (He) and deuterium (D) ratio in the plasma to the feedback control of the plasma boundary gas.

[0042] The application is not simply used for the spectral line intensity ratio, but establishes a helium-deuterium ratio calculation formula based on the photon emission coefficient (PEC) of the ADAS collision-radiation model, so that the diagnostic result has a clear physical meaning: the multi-energy level collision-radiation model of helium (He) and deuterium (D) ions is established by using the ADAS208 program (quasi-static equilibrium population solver) in the atomic data and analysis structure (ADAS) database. The model considers the processes of electron collision excitation, spontaneous radiation transition, collision de-excitation, radiation recombination and coupling between metastable energy levels. For a given electron temperature and electron density , the photon emission coefficients (PEC) of He 468.6 nm and Dα656.3 nm spectral lines meet the following relationship according to the ADAS theory, the spectral line emissivity ε and the ground state ion density n ion .

[0043] ; ;

[0044] wherein, is the volume emissivity of the He 468.6 nm spectral line, is the volume emissivity of the Dα 656.3 nm spectral line, is the excitation photon emission coefficient, which reflects the photon generation efficiency per unit electron density and per unit ion density. The ion density ratio of helium and deuterium and the spectral line intensity ratio are theoretically related, wherein, is the helium spectral line integral intensity; is the deuterium spectral line integral intensity, the collision-radiation relationship can be used to connect the helium and deuterium ion density ratio and the ratio of spectral line volume emissivity through the PEC:

[0045] ;

[0046] The above formula gives the theoretical corresponding relationship between the fuel ion density ratio and the radiation intensity, wherein the PEC term is calculated by the ADAS208 collision-radiation model, and reflects the atomic physical process. Then the emissivity is transformed into the actual measurable line intensity ratio by the subsequent correlation. Where, And are the excitation photon emission coefficients of He 468.6 nm line and Dα 656.3 nm line respectively, giving the number of photons produced by electron collisional excitation per unit electron density And unit ground state ion density , are functions calculated by ADAS208 collision-radiation solver under given electron temperature And electron density . In typical tokamak edge plasma parameter range, the ratio of PEC is relatively insensitive to the variation of temperature and density, and can be approximated as a physical constant or weak function. In actual measurement, the integral intensity I detected by the spectrometer and the emissivity ε are also affected by the line-of-sight geometric factor L, optical transmission efficiency And absolute response of the detector , which can be obtained by substituting the above formula.

[0047] ;

[0048] Where, And are the effective observation lengths corresponding to the helium line-of-sight and deuterium line-of-sight respectively; And are the total transmission efficiencies of the optical path at the wavelengths of the helium line and the deuterium line respectively; And are the absolute response coefficients of the detector at the wavelengths of the two lines respectively; the present application combines the PEC ratio calculated by the above ADAS theory With the relative response function of the optical system of the device to define the comprehensive calibration coefficient K:

[0049] ; ;

[0050] Where, Is a normalization constant, And Are the comprehensive calibration coefficients of the helium line and the deuterium line, which contain not only the PEC ratio given by the ADAS collision-radiation model, but also the relative geometric factor, optical transmission efficiency and detector response of the diagnostic system at the wavelengths of the two lines, and are used to transform the measured integral intensity ​​The mapping to the corresponding ion density weight is solved by least square fitting of several groups of standard discharge data of known fuel composition (for example, the working conditions determined independently by mass spectrometer or neutron yield) to obtain the optimal coefficient in the embodiment and Therefore, the coefficients 14.4 and 55 essentially contain the theoretical prediction of the ADAS atomic physical process and the spectral response characteristics of the specific diagnostic system. The calculation formula of the coefficients is as follows:

[0051] ;

[0052] Both the physical correctness (based on the CR (collision-radiation) model) and the measurement error of the hardware system (based on experimental calibration) are ensured, so as to realize high-precision online real-time diagnosis.

[0053] A tokamak plasma feedback control method based on real-time calculation of helium deuterium ratio, comprising the following steps:

[0054] Step 1, establishing a plasma discharge spectrum diagnosis and data acquisition platform. An optical acquisition system is arranged at a plane in the tokamak device, and an optical fiber is connected to a multi-channel high-resolution Avantes spectrometer, and an observation channel containing a helium spectral line and a deuterium spectral line target waveband is configured; the automatic addressing, initialization, integration time and measurement time setting and trigger mode configuration of the spectrometer are realized based on a MATLAB graphical interface program, and continuous frame-by-frame acquisition of the spectral signal during plasma discharge is realized.

[0055] Step 2, realizing online frame-by-frame calculation of helium deuterium ratio. The spectral measurement subsystem uses a multi-channel high-resolution Avantes spectrometer to synchronously measure the waveband of the helium spectral line and the deuterium spectral line during plasma discharge, and outputs the wavelength array and the corresponding intensity data. The data acquisition and calculation subsystem realizes automatic discovery, initialization, trigger configuration and continuous acquisition of the spectrometer based on a MATLAB graphical interface program, and automatically reads the current frame spectrum after each integration, pre-processes and numerically integrates the specified helium and deuterium spectral line window, and calculates the He / (He+D) ratio in real time. The spectral pretreatment includes Savitzky-Golay smoothing filter denoising and baseline correction based on moving window minimum value to suppress the influence of high-frequency noise and continuous background radiation on the spectral line integration result. In the pre-set narrow wavelength range of the helium spectral line (near 468.6 nm) and the deuterium spectral line (near 656.3 nm), the trapezoidal integration or equivalent numerical integration method is used to calculate the integration intensity of the two spectral lines, and the He / (He+D) or equivalent helium deuterium ratio diagnostic quantity is obtained by weighting the helium line and the deuterium line according to the empirically calibrated sensitivity coefficient.

[0056] Step 3, construct the helium deuterium ratio diagnostic quantity to the high-speed mapping of the reflection memory. Load the PCIE reflection memory card driver on the control computer, call the reflection memory card API to open the specified board channel, configure the shared memory offset address and data format; when the new helium deuterium ratio result is obtained in step 2, the diagnostic quantity is written into the predetermined address area of the reflection memory according to the short integer coding, and the data is broadcast in real time to the computing nodes of the tokamak plasma control system by using the PCIE and fiber link, so that the helium deuterium ratio diagnostic quantity is shared at the hardware level between multiple control nodes at high speed.

[0057] Step 4, realize the plasma fuel feedback control driven by the helium deuterium ratio. In the tokamak plasma control system (PCS), the latest helium deuterium ratio diagnostic quantity is periodically read from the reflection memory during the experiment, and is compared with the preset target fuel ratio or operation window in real time to construct a control loop with the helium deuterium ratio as the feedback signal; based on the control error, the adjustment amount of the helium and deuterium gas inlet flow, the gas injection pulse width or the related fuel actuator is calculated, and is transmitted to the fuel supply system through the PCS to realize the closed-loop adjustment of the plasma helium deuterium fuel component. The control loop can set different target helium deuterium ratio curves according to different stages of the tokamak discharge, so as to realize the segmented fuel optimization control in the discharge start, flat top and shutdown stages.

[0058] Further, in step 1, the MATLAB graphical interface program communicates with the discharge control system through the UDP network interface, receives the measurement instructions including the discharge number, the measurement time length and the data file name, automatically completes the spectrum acquisition task configuration and the helium deuterium ratio real-time calculation during the discharge, and archives and saves the multi-channel spectrum and time sequence data according to the discharge number, so as to facilitate the offline physical analysis in the later stage.

[0059] Further, in step 2, the helium spectral line center wavelength is preferably about 468.6 nm, the deuterium spectral line is preferably about 656.3 nm, and the integral band is selected as a narrow interval of ±0.5-1.0 nm around the center, and the integral result is approximately linearly corresponding to the helium and deuterium particle density ratio in the plasma through a calibration coefficient, so as to ensure that the diagnostic quantity has a monotonic and controllable response characteristic to the change of the fuel component.

[0060] Further, in step 3, a continuous address area is reserved in the shared memory space of the reflection memory card for the helium deuterium ratio diagnostic quantity, and the control program writes the latest helium deuterium ratio at a fixed sampling period, and at the same time, can write an effective flag or a time stamp in the adjacent address, so that the PCS can judge the freshness and synchronization of the data.

[0061] The present application provides a more specific embodiment, and the method of the application specifically comprises the following steps:

[0062] Step 1: Spectral acquisition and device control

[0063] Spectrometer initialization, control PC running AvsMeasure program, call search and initialize connected Avantes spectrometer, get device handle, pixel number, wavelength array and other information and save to structure for subsequent measurement. Parameter setting, in the function, by setting integral time, average number, trigger mode, saturation detection and other parameters for each spectrometer, integral time is typically set to 1-10 ms to meet the real-time diagnosis demand of milliseconds. Trigger and acquisition cycle, according to whether to use external trigger mode, the function configures the synchronization mode; in the main loop, periodically call trigger single frame acquisition, and through polling data ready state, then read a frame of spectral data and store it. The process ensures continuous high-frequency acquisition under low CPU occupation.

[0064] Step 2: Key observation window selection and spectral line intensity calculation

[0065] The program determines the pixel index near 468.6 nm and 656.3 nm according to the array, and the selection of integral width considers the wavelength resolution of the spectrometer, the actual line shape broadening of the plasma and the total emission coefficient of the spectral line given by the ADAS collision-radiation model. Through statistical analysis of a large number of historical discharge data, the integral window of He and Dα spectral lines is limited to a wavelength range covering about twice the line width, so that the spectral line area obtained by integration can represent the emission intensity of the whole spectral line and be consistent with the photon emission coefficient given in the ADAS database. Then, under the integral width, through experimental calibration of the known helium and deuterium gas ratio, the weighted coefficients 14.4 and 55 are obtained by fitting, so that the influence of integral width selection on the diagnosis result is absorbed into the coefficients. Background subtraction and integration, for each frame of spectrum, select several pixels at the window edge to estimate the continuous background level, subtract the background from the measured count in the window to get the net spectral profile; then use the trapezoidal rule to numerically integrate all pixels in the window to get and The integral result can be bound with the time stamp to form the time evolution sequence of helium and deuterium spectral lines.

[0066] Step 3: Real-time calculation of helium and deuterium ratio and result uploading

[0067] Real-time calculation, after each integral is completed, call the helium and deuterium ratio calculation sub-function, and substitute the current frame of and into:

[0068] ;

[0069] The current He / (He+D) ratio is obtained. The program writes the result together with the time into the shared memory and displays it in real time in the GUI curve, as shown in Figure 2(a) 、 2(b) and Figure 3 Figure 2(a) is a helium-deuterium ratio time evolution curve (reference value) calculated by using a conventional offline physical analysis program, and figure 2(b) is a helium-deuterium ratio time evolution curve calculated and uploaded by using the real-time online diagnostic system of the application. The comparison of the two figures shows that the real-time waveform calculated by the method of the application (figure 2(b)) is highly consistent with the offline physical analysis result (figure 2(a)) in trend, amplitude and dynamic response characteristics, verifying the accuracy of the real-time algorithm. Figure 3 Figure 3 is a waveform diagram of the experiment of plasma fuel component feedback control using the real-time helium-deuterium ratio diagnostic system of the application (EAST shot #158534), (a) helium-deuterium ratio control effect: showing the time evolution of the set target value (Target), real-time measured value (real) and control error (Error).(b) gas filling system operation: showing the curve of the helium gas filling valve voltage varying with time driven by the feedback control system.

[0070] The real-time online result of EAST shot #158532 is highly consistent with the offline post-processing result in waveform and amplitude. RFM transmission, the control PC writes into the pre-defined address space through the PCIe reflective memory card. The PCS reads the address on the same RFM network at a fixed period, that is, the latest helium-deuterium ratio diagnostic value can be obtained synchronously in the control cycle, the communication delay is less than the millisecond level, meeting the needs of feedback control.

[0071] Embodiment:

[0072] Feedback control implementation, in the PCS, the real-time helium-deuterium ratio is subtracted from the set target curve target, the built-in PID controller calculates the control voltage command of the helium gas filling valve according to the difference and its time rate of change, and sends it to the gas filling system through an independent optical fiber channel to realize automatic adjustment of the helium injection flow. Gas control effect, in the experiment of EAST shot #158534, the helium-deuterium ratio closed-loop control is started at 3.0s. Figure 3 (a) shows that the real-time measured He / (He+D) curve rises from the initial about 7% under the feedback effect and stabilizes near the target value 14%, and the control error gradually converges to close to zero; Figure 3 (b) shows that the corresponding helium gas filling valve voltage rapidly rises at the beginning of control, then gradually falls with the decrease of error and fine-tunes in a relatively narrow range, without obvious oscillation, proving that the real-time diagnosis and feedback algorithm of the application has good stability and control effect.

[0073] Through the above system structure and implementation steps, the application realizes millisecond-level real-time measurement and closed-loop control of the plasma boundary helium-deuterium ratio by using the Avantes spectrometer and the specially designed MATLAB acquisition and calculation program, which not only retains the physical reliability of the ADAS collision-radiation model, but also takes into account the engineering requirements for low delay and high robustness.

[0074] Further, in order to improve the physical reliability and engineering robustness of the real-time diagnosis result of the helium-deuterium ratio, the application introduces a collision-radiation model constraint and an experimental calibration correction mechanism in the algorithm design. On the one hand, based on the photon emission coefficients of He and Dα spectral lines given in the ADAS database, the theoretical intensity ratio is calculated within the typical temperature and density range of the tokamak boundary plasma, and the range of the weighting coefficient in the helium-deuterium ratio calculation formula is determined accordingly, so that the real-time calculation result meets the consistency constraint of the collision-radiation model in physics. On the other hand, combined with a large amount of historical discharge experiment data with known filling ratio, the weighting coefficient and the integral broadening parameter are jointly calibrated and optimized, and the hardware errors such as optical transmission efficiency, non-linear detector response and background radiation are absorbed into the coefficient, thereby ensuring the calculation efficiency while significantly improving the diagnosis accuracy and repeatability.

[0075] Preferably, in terms of original spectrum signal processing, the application introduces time sequence signal processing techniques such as median filtering and baseline subtraction to process the intensity sequence in the key observation window output by the Avantes spectrometer, and on this basis, uses the trapezoidal integral method with fixed integral broadening to calculate the integral intensity of He and Dα spectral lines. After comparing the offline complete collision-radiation calculation results with the multi-shot experimental data, the application determines a set of optimal integral window and weight coefficient, so that the helium-deuterium ratio calculated in real time online has an average relative error controlled within a preset threshold during the entire discharge flat-top phase, while maintaining a millisecond-level time resolution, meeting the real-time and accuracy requirements of fuel component feedback control in the long-pulse operation of tokamak plasma.

Claims

1. A tokamak plasma feedback control system based on real-time calculation of the helium-deuterium ratio, characterized in that, include: Automatic spectral acquisition module, real-time helium-deuterium ratio calculation module, and data transmission and feedback control module; The automatic spectral acquisition module is used to acquire emission spectral data of helium-containing characteristic spectral lines and deuterium characteristic spectral lines during the discharge process of the tokamak device through a spectral diagnostic system arranged in the plasma boundary divertor and a multi-channel high-resolution fiber optic spectrometer. The real-time helium-deuterium ratio calculation module is connected to the automatic spectrum acquisition module. It is used to preprocess the emission spectrum data and calculate the spectral line integral intensity within a preset helium spectral line wavelength window and deuterium spectral line wavelength window in each sampling period. The helium-deuterium ratio diagnostic value He / (He+D) at the current moment is calculated according to the weighting coefficient. The data transmission and feedback control module includes a reflective memory network interface and a plasma control system (PCS). The reflective memory network interface is used to send the helium-deuterium ratio diagnostic value to the plasma control system in real time via shared memory. The plasma control system generates a gas filling control command based on the deviation between the received helium-deuterium ratio diagnostic value and the preset target value, and sends it to the gas filling system to achieve closed-loop control of the tokamak plasma fuel composition.

2. The system according to claim 1, characterized in that, The automatic spectral acquisition module includes: An imaging lens and focusing optical element located outside the vacuum chamber of the tokamak are used to focus the plasma emitted light from the divertor region or boundary region onto the end face of the fiber array; multiple quartz multimode fibers are used to transmit the emitted light to a multi-channel high-resolution fiber optic spectrometer; the wavelength coverage range of the fiber optic spectrometer is 400~900 nm, including at least observation channels covering the He spectral line at 468.6 nm and the Dα spectral line at 656.3 nm.

3. The system according to claim 1 or 2, characterized in that, The real-time helium-deuterium ratio calculation module includes a spectral acquisition and processing program running on a control computer. This program, through the spectrometer driver interface, performs the following functions: automatic addressing and initialization of the spectrometer; setting the integration time, averaging times, and trigger mode; and continuous frame-by-frame acquisition of the tokamak discharge process. After each frame of data acquisition is completed, a first key observation window containing the He 468.6 nm spectral line and a second key observation window containing the Dα 656.3 nm spectral line are extracted. The spectral intensities within these windows are filtered for noise reduction and baseline subtraction. The integrated intensity of the helium spectral line is obtained using a numerical integration method. Integral intensity of deuterium spectral lines .

4. The system according to claim 3, characterized in that, The helium-deuterium ratio real-time calculation module calculates the helium-deuterium ratio according to the following formula: ； in, and The weighting coefficients, determined based on the photon emission coefficients of the collision-radiation model and experimental calibration results, characterize the combined response sensitivity of the optical system and detector to helium and deuterium spectral lines, respectively.

5. The system according to claim 4, characterized in that, The weighting coefficients and The following steps were taken to obtain the theoretical intensity ratio: based on the photon emission coefficients of the He 468.6 nm and Dα 656.3 nm spectral lines in the ADAS database, the theoretical intensity ratio was calculated within the typical electron temperature and electron density range at the tokamak boundary; historical experimental data with known helium-deuterium filling ratios from multiple guns were selected, and the theoretical intensity ratio was used to jointly calibrate the optical path transmittance and detector quantum efficiency; the set of ratios that minimized the deviation between the real-time calculation results and the reference helium-deuterium ratio was obtained through least squares fitting. and .

6. The system according to any one of claims 1 to 5, characterized in that, In the data transmission and feedback control module, the reflective memory network adopts a PCIe bus structure, and each node is configured with a reflective memory card. The control computer writes the helium-deuterium ratio calculated in real time into the local reflective memory in the form of data frames. The plasma control system reads the helium-deuterium ratio data from the corresponding address within the control cycle, realizing microsecond-level data synchronization between multiple nodes.

7. The system according to any one of claims 1 to 6, characterized in that, The plasma control system has a built-in PID controller. The PID controller uses the helium-deuterium ratio diagnostic value as the controlled variable and the preset helium-deuterium ratio target value as the set value. It calculates the control voltage or opening command of the gas filling valve based on the difference between the two values ​​and can optionally superimpose a feedforward command to compensate for the baseline gas injection.

8. A tokamak plasma feedback control method based on real-time calculation of the helium-deuterium ratio, characterized in that, The system described in any one of claims 1 to 7 is used to perform the following steps: Step 1: Establish a plasma discharge spectral diagnosis and data acquisition platform. Deploy a spectral diagnosis system at the boundary field of view of the tokamak device and connect the optical fiber to a multi-channel high-resolution fiber optic spectrometer. Configure observation channels that include target bands of helium and deuterium spectral lines to continuously acquire data in frames throughout the entire discharge process. Step 2: In each sampling period, noise filtering and baseline correction are performed on the spectral data output by the observation channel. Numerical integration is performed within the preset wavelength windows of helium and deuterium spectral lines. The He / (He+D) helium-deuterium ratio is calculated in real time according to the preset weighting coefficients. Step 3: The helium-deuterium ratio diagnostic value obtained in Step 2 is transmitted to the plasma control system in real time via a reflective memory network; Step 4: The plasma control system runs a feedback control algorithm based on the control error between the helium-deuterium ratio diagnostic value and the target value, generates control commands for the helium and / or deuterium filling valves, and drives the filling system to execute them, thereby achieving online adjustment of the boundary helium-deuterium ratio during the tokamak discharge process.

9. The method according to claim 8, characterized in that, In step 2, noise filtering employs Savitzky-Golay smoothing or median filtering, while baseline correction uses moving window minimum or polynomial fitting methods to suppress the influence of rapid noise fluctuations and continuous spectral background on the spectral line integration results.

10. The method according to claim 8 or 9, characterized in that, On the tokamak device, representative discharges from multiple sources were selected for online calculation and offline complete collision-radiation calculation results were compared and verified. When the average relative error of the helium-deuterium ratio diagnosed in real time during the discharge level peak stage was lower than the preset threshold, the corresponding integral window and weighting coefficient combination was fixed as the operating parameter for conventional feedback control in subsequent long pulse discharge experiments.

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