Method for measuring two-dimensional distribution of impurities in divertor area of nuclear fusion device

Abstract

The invention relates to the technical field of nuclear fusion, in particular to a method for measuring two-dimensional distribution of impurities in a divertor area of a nuclear fusion device, high-spatial-resolution impurity distribution can be obtained through a visible light imaging system and collection of plasma radiation image data, the transport mechanism of the impurities in an edge area can be researched more finely, and the measurement accuracy of the impurities in the divertor area is improved. After a plasma image is collected, the plasma image is corrected and absolutely calibrated so as to ensure the accuracy of measurement data, and finally, the corrected plasma image is subjected to grid division and tomographic inversion so as to obtain a spatial distribution diagram of impurities. According to the invention, the plasma boundary radiation characteristic and the divertor region impurity distribution can be measured, so that the space distribution and the impurity transport rule of the divertor region impurities can be given, and key physical information can be provided for fusion device plasma impurity control and radiation divertor related experiments.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of nuclear fusion, in particular to a method for measuring two-dimensional distribution of impurities in the divertor region of a nuclear fusion device. BACKGROUND

[0002] In a magnetic confinement nuclear fusion device, the basic components of the plasma are hydrogen and its isotopes deuterium and tritium, and other components are often defined as impurities. In a nuclear fusion device, the interaction between the plasma and the plasma-facing materials (first wall materials) includes physical and chemical processes such as sputtering, blistering, arcing, and thermal shock, which is one of the main sources of impurities. At the same time, the first wall of the vacuum chamber usually adsorbs a large number of molecules or atoms, which enter the plasma through low-energy desorption processes such as thermal desorption, particle bombardment, and chemical reactions, thereby forming impurities. In addition, the product of the fusion reaction contains alpha particles, which is also an inevitable source of impurities in the tokamak. According to the plasma quasi-neutrality condition, the hydrogen isotope ion density as the ideal fusion fuel should be equal to the electron density, and the charge number of the impurity ion is several times or even dozens of times the charge number of the fuel ion. At the same electron density, the presence of each impurity ion is equivalent to replacing fuel ions equal to its own charge number, especially when high-Z impurities reach a certain concentration, which has a strong dilution effect on fuel ions. According to the coronal model theory, the plasma radiation power loss is proportional to the electron and ion density, so the impurity core will lead to an increase in radiation loss, thereby dissipating energy and reducing the confinement quality of the plasma.

[0003] Among them, the divertor is one of the core components of the magnetic confinement nuclear fusion tokamak device. As the first contact point between the plasma and the wall, the divertor is used to exclude impurities and heat, so that the main plasma avoids impurity contamination. However, due to the complex magnetic field topology and plasma interaction, especially near the X-point, part of the impurities will enter the main plasma, reducing the plasma confinement quality. Therefore, understanding the impurity distribution and transport in the edge divertor region is of great significance to improve the performance of the plasma.

[0004] In addition, the two-dimensional impurity distribution in the divertor region has a significant impact on plasma confinement, heat load management, and material erosion. Moreover, these impurities not only affect the fusion efficiency, but also can cause rapid erosion and damage to the materials. However, the existing two-dimensional impurity distribution measurement methods have limited coverage and low accuracy.

[0005] Therefore, developing a full-area, high-precision, and high-resolution measurement method is an important technical requirement for efficient fusion reaction and long-term stable operation of the device. SUMMARY

[0006] The application provides a method for measuring two-dimensional distribution of impurities in a divertor region of a nuclear fusion device.

[0007] The application is achieved by the following technical solutions: The application provides a method for measuring two-dimensional distribution of impurities in a divertor region of a nuclear fusion device, comprising the following steps: Collecting plasma radiation image data through a visible light imaging system; Correcting and absolutely calibrating the plasma image; Grid dividing and tomographic inversion are performed on the corrected plasma image to obtain a spatial distribution map of impurities.

[0008] It should be noted that in the fusion device, impurity particles are in a partially ionized state at the edge plasma region and radiate very strong characteristic spectral lines. The wavelengths of some spectral lines are in the ultraviolet band. The distribution of related impurities can be obtained by measuring the related characteristic spectral lines through a vacuum ultraviolet system, which is used for studying impurity transport. Therefore, the vacuum ultraviolet system is one of the main diagnostic systems for measuring impurity distribution. Because the spectrum in the ultraviolet band is easily absorbed, the vacuum ultraviolet system usually adopts a relatively long vacuum light pipe to directly guide the ultraviolet spectrum to a spectrometer for measurement and analysis. However, due to the range of the detection field of view of the system and the detection structure of the spectrometer, the vacuum pipe is generally relatively long. Moreover, the measurement result is a line integral signal. For the complex magnetic topology structure of the divertor region, it is relatively difficult to obtain the impurity distribution through mathematical inversion. Therefore, it is difficult to use the vacuum ultraviolet system to carry out the measurement and research of the impurity distribution in the divertor region, which affects the research progress of the impurity transport mechanism and control in the divertor region.

[0009] The inventor has found that in the divertor region, the temperature of the plasma is generally low, and in addition to the rich ultraviolet spectrum, there are also a large number of visible band impurity characteristic spectrum lines, so the impurity distribution and its transport mechanism can also be studied through the measurement of the visible spectrum. In addition, with the development of optical systems, a large number of tangential observation systems have been developed on the magnetic confinement nuclear fusion device, which can clearly measure the radiation distribution of the visible band. By installing a suitable narrow-band optical filter between the optical path structure and the detector, the two-dimensional impurity characteristic spectrum line radiation distribution can be obtained. On the basis of assuming that the plasma is toroidally symmetric (the plasma is generally toroidally symmetric), the two-dimensional spatial distribution of the impurity spectrum line radiation intensity can be obtained by means of mathematical inversion (Tomography), and after calibration correction, the two-dimensional impurity spatial distribution can be obtained. Tomography grids the plasma region, so that the inversion process is independent of the magnetic configuration structure. And the visible detector has a very high pixel point, that is, a detection channel, so that the impurity distribution with high spatial resolution can be obtained, which greatly promotes the research on the impurity transport mechanism in the edge region.

[0010] Therefore, the nuclear fusion device divertor region impurity two-dimensional distribution measuring method provided by the present application can obtain high spatial resolution impurity distribution through the visible light imaging system, which helps to more finely study the impurity transport mechanism in the edge region. After the plasma image is collected, the plasma image is corrected and absolutely calibrated to ensure the accuracy of the measurement data. Finally, the corrected plasma image is grid divided and tomographically inverted to obtain the spatial distribution of the impurity.

[0011] Compared with the vacuum ultraviolet imaging method, the visible optical imaging system does not need a long vacuum light collecting pipe, and the system design and operation are more simple. And it is suitable for various magnetic confinement nuclear fusion devices, and is not sensitive to the complex magnetic topology structure of the divertor region, so the measurement result is more accurate and reliable. It is helpful to control the heat load in the fusion reactor, study the material erosion and fuel retention phenomenon, optimize the design of the fusion reactor, especially in the selection of the divertor and wall materials and the geometric structure design, so as to realize the important technical requirements of efficient fusion reaction and long-term stable operation of the device.

[0012] In summary, the nuclear fusion device divertor region impurity two-dimensional distribution measuring method provided by the present application can measure the plasma boundary radiation characteristics and the impurity distribution in the divertor region to give the spatial distribution of the impurity in the divertor region and the impurity transport law, and provide key physical information for the plasma impurity control of the fusion device and the related experiment of the radiation divertor.

[0013] In an optional embodiment of the present application, the method further comprises the step of installing the visible light imaging system so that the visible light imaging system can cover the entire divertor region to ensure that the visible light imaging system can acquire the plasma image in the divertor region.

[0014] In an optional embodiment of the present application, the visible light imaging system is installed at the divertor X-point and performs tangential observation to ensure that the visible light imaging system can cover the lower divertor region so that the first wall region observed by the visible light imaging system contains the regions of all the inner and outer divertor target plates, which is suitable for any divertor discharge configuration, thereby enabling high spatial and temporal resolution measurement of the impurity distribution in the divertor region.

[0015] In an optional embodiment of the present application, the imaging surface of the visible light imaging system coincides with the detector to ensure the accuracy of the plasma image information.

[0016] In an optional embodiment of the present application, the method further comprises the step of installing a narrow-band filter between the imaging light path of the visible light imaging system and the detector to filter out noise by the narrow-band filter to reduce the influence of the plasma radiation background on the measurement.

[0017] In an optional embodiment of the present application, the center wavelength of the narrow-band filter is 514 nm and the bandwidth is 1 nm.

[0018] In an optional embodiment of the present application, the method for correcting the plasma image is to normalize the light transmission curve of the narrow-band filter and the impurity characteristic spectral line distribution to ensure the accuracy of the measurement.

[0019] In an optional embodiment of the present application, the step of absolute calibration of the plasma image is: using a standard light source as a known power light source, which is imaged on the detector after passing through the light path structure and the narrow-band filter; comparing the measured intensity of the detector with the known light source to obtain the absolute calibration coefficient of the impurity characteristic spectral line; changing different characteristic wavelengths to obtain the comparative calibration coefficients of different impurity spectral lines.

[0020] In an optional embodiment of the present application, the grid division method is to divide the region in the field of view of the visible light imaging system into a cubic grid and assume that the impurity radiation in each grid is equal, wherein the impurity radiation is symmetrical in the toroidal direction.

[0021] In an optional embodiment of the present application, the tomographic inversion method is to perform tomographic inversion by using the least square method, to simplify the three-dimensional tomographic inversion into two-dimensional inversion on the plasma poloidal cross section, and to obtain the spatial distribution map of the impurities.

[0022] Compared with the prior art, the application has the following advantages and beneficial effects: The nuclear fusion device divertor region impurity two-dimensional distribution measuring method provided by the application can obtain high spatial resolution impurity distribution, and is helpful to more finely study the edge region impurity transport mechanism. BRIEF DESCRIPTION OF DRAWINGS

[0023] In order to more clearly illustrate the technical solutions of the embodiments of the application, the following will briefly introduce the drawings needed to be used in the embodiments. It should be understood that the following drawings only show some of the embodiments of the application, and therefore should not be considered as limiting the scope. For those of ordinary skill in the art, other related drawings can also be obtained without creative labor based on these drawings.

[0024] In the drawings: Figure 1 The flowchart of the nuclear fusion device divertor region impurity two-dimensional distribution measuring method provided by the embodiment of the application is shown in the figure. Figure 2 The installation schematic diagram of the visible light imaging system provided by the embodiment of the application is shown in the figure. Figure 3 The image schematic diagram of the divertor region targeted by the embodiment of the application is shown in the figure. Figure 4 The comparison schematic diagram of the impurity characteristic spectral line radiation curve and the filter transmittance curve in the embodiment of the application is shown in the figure. Figure 5 The absolute calibration schematic diagram provided by the embodiment of the application is shown in the figure. Figure 6 The measurement result figure of the embodiment of the application is shown in the figure. Figure 7 The impurity spatial distribution figure of the embodiment of the application is shown in the figure.

[0025] 1-visible imaging system, 2-narrow band filter, 3-divertor region, 4-target plate inside the divertor, 5-target plate outside the divertor, 6-X point, 7-absolute calibration structure, 8-standard light source, 9-relative calibration factor, 10-detector. DETAILED DESCRIPTION

[0026] To make the objects, technical solutions and advantages of the embodiments of the present application clearer, the following will be combined with the accompanying drawings for the embodiments of the present application to make a clear and complete description of the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only some but not all of the embodiments of the present application. The components of the embodiments of the present application described and shown in the accompanying drawings can be arranged and designed in various different configurations.

[0027] The following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the present application claimed, but only represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without making creative efforts fall within the scope of the present application.

[0028] Those skilled in the art should understand that the embodiments of the present application can be provided as a method, a system or a computer program product. Therefore, the present application can take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Moreover, the present application can take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0029] It should be noted that in the fusion device, impurity particles are in a partially ionized state at the edge plasma region and radiate very strong characteristic spectral lines. The wavelengths of some spectral lines are in the ultraviolet band, and the measurement of the related characteristic spectral lines by the vacuum ultraviolet system can give the distribution of the related impurities, which is used for studying impurity transport. Therefore, the vacuum ultraviolet system is one of the main diagnostic systems for measuring the distribution of impurities. Because the spectrum in the ultraviolet band is easily absorbed, the vacuum ultraviolet system usually uses a relatively long vacuum light pipe to directly guide the ultraviolet spectrum to a spectrometer, so as to perform measurement and analysis. However, due to the range of the detection field of view of the system and the detection structure of the spectrometer, the vacuum pipe is generally relatively long. And the measurement result is a line integral signal, and for the complex magnetic topology structure of the divertor region, it is relatively difficult to obtain the impurity distribution by mathematical inversion. Therefore, it is difficult to carry out the measurement and research of the impurity distribution in the divertor region by using the vacuum ultraviolet system, which affects the research progress of the impurity transport mechanism and control in the divertor region.

[0030] The inventors have found that in the divertor region, the temperature of the plasma is generally low, and in addition to the rich ultraviolet spectrum, there are also a large number of impurity characteristic spectrum lines in the visible band. Therefore, the impurity distribution and its transport mechanism can also be studied by measuring the visible spectrum. In addition, with the development of optical systems, a large number of tangential observation systems have been developed on the magnetic confinement nuclear fusion device, which can clearly measure the radiation distribution in the visible band. By installing a suitable narrow-band optical filter between the optical path structure and the detector, a two-dimensional impurity characteristic spectrum line radiation distribution can be obtained. On the basis of the assumption of the toroidal symmetry of the plasma (the plasma is generally toroidally symmetric), the two-dimensional spatial distribution of the impurity spectrum line radiation intensity can be obtained by means of mathematical inversion (Tomography). After calibration and correction, the two-dimensional impurity spatial distribution can be obtained. Tomographic inversion grids the plasma region, so that the inversion process is independent of the magnetic configuration structure. Moreover, the visible detector has a high number of pixels, i.e. detection channels, so that a high spatial resolution impurity distribution can be obtained, which greatly promotes the study of the impurity transport mechanism in the edge region.

[0031] In order to solve the above-mentioned problems, the inventors have innovatively designed the following technical solutions, and the specific implementation schemes of the present application will be described in detail below with reference to the accompanying drawings.

[0032] Embodiment In combination Figure 1 The embodiment provides a method for measuring two-dimensional impurity distribution in a divertor region of a nuclear fusion device, comprising the following steps: S10, install a visible light imaging system so that the visible light imaging system can cover the entire divertor region 3 to ensure that the visible light imaging system can obtain a plasma image in the divertor region 3.

[0033] Specifically, the visible light imaging system is installed at the divertor X point 6 and performs tangential observation to ensure that the visible light imaging system can cover the lower divertor region 3, so that the first wall region observed by the visible light imaging system contains the regions of all the inner and outer divertor target plates, which is suitable for any divertor discharge configuration, thereby enabling high temporal and spatial resolution measurement of the impurity distribution in the divertor region 3.

[0034] It can be understood that the visible light imaging system is installed at a suitable position near the divertor X point 6 of the magnetic confinement nuclear fusion device to ensure that it can cover the entire divertor region 3, especially the region near the X point 6.

[0035] In combination Figure 2 and Figure 3In order to image the toroidal plasma in the whole field of view, the lens of the imaging system is designed as a large depth of field structure, i.e. a telescope structure. Specifically, the visible light imaging system comprises a sampling lens mounted on the attachment of the bias filter, the light entering direction of the sampling lens is tangential to the bias filter, and a mirror is arranged outside the bias filter to make the light exiting the sampling lens parallel to the collection surface of the detector 10. A lens group is usually arranged between the detector 10 and the mirror to ensure that the distance between the detector 10 and the bias filter is sufficient, so that the plasma radiation is reflected by the front lens multiple times, and the image plane is led out of the vacuum chamber and imaged on the detector 10, and the image plane is ensured to coincide with the detector 10. This design can clearly measure the plasma radiation distribution of the whole bias filter area 3, and provide basic data for subsequent measurement of impurity distribution.

[0036] S20, a narrow-band filter 2 is installed between the imaging light path of the visible light imaging system and the detector 10 to filter out noise through the narrow-band filter 2, thereby reducing the influence of the plasma radiation background on the measurement.

[0037] Specifically, the impurity characteristic spectrum is a line spectrum, but due to the Doppler broadening effect, the spectrum is in a Gaussian distribution. However, the half-width of the characteristic spectrum is still very narrow, usually in the order of several Å. Therefore, in order to reduce the influence of the plasma radiation background on the measurement, a narrow-band filter 2 needs to be installed between the imaging light path and the detector 10.

[0038] It is known that the narrow-band filter is subdivided from the band-pass filter, and its definition is the same as that of the band-pass filter, that is, the filter allows light signals in a specific waveband to pass through, and light signals deviating from both sides of the waveband are blocked. The passband of the narrow-band filter is relatively narrow, generally less than 5% of the center wavelength. For the filter of the nuclear fusion device, the narrow-band filter 2 with the impurity characteristic spectrum as the center wavelength and a bandwidth of 1 nm is usually selected.

[0039] It should be understood that the selection of the narrow-band filter 2 needs to be based on the impurity characteristic spectrum to be measured. For example, when measuring the CII impurity spectrum, a filter with a center wavelength of 514 nm and a bandwidth of 1 nm can be selected; when measuring the OII impurity spectrum, a narrow-band filter 2 with a center wavelength of 615 nm and a bandwidth of 1 nm is selected.

[0040] After the narrow-band filter 2 is selected, the selected narrow-band filter 2 is installed between the imaging light path and the detector 10, which can reduce the influence of the plasma radiation background on the measurement and ensure that the radiation signal of the impurity characteristic spectrum can be effectively separated.

[0041] S30, acquiring plasma radiation image data through the visible light imaging system.

[0042] That is, start the visible light imaging system to start collecting plasma radiation image data. During the collection process, ensure that the system is stable and that clear and complete plasma radiation images are collected. Finally, record the collected plasma radiation image data to provide a basis for subsequent data processing and analysis.

[0043] S40, correct and absolutely calibrate the plasma image.

[0044] In this embodiment, the method for correcting the plasma image is to normalize the light transmission curve of the narrowband filter with the impurity characteristic spectral line distribution to obtain a correction factor to ensure the accuracy of the measurement.

[0045] In combination Figure 4 It can be understood that the light transmission curve of the filter is usually Gaussian distribution, and therefore, for the accuracy of the measurement, the light transmission curve of the filter needs to be corrected with the spectral line distribution, i.e., the correction factor of the overlapping area in the wavelength direction after normalization. Since the light transmission amount needs to be considered, the bandwidth of the filter is usually larger than the radiation width of the impurity characteristic spectral line, and therefore, the correction factor mainly considers the shadow area of the impurity characteristic spectral line to be measured. In addition, since the Doppler broadening is related to the plasma temperature, the correction factor of the spectral line is different at different temperatures. At the same time, the radiation intensity of the impurity characteristic spectral line is related to the impurity concentration, and therefore, the impurity density can be calculated through the absolute intensity measurement of the impurity characteristic spectral line.

[0046] Specifically, the correction step of the light transmission curve of the filter is: S411, obtain the light transmission curve of the filter.

[0047] Specifically, the light transmission curve (transmittance changes with wavelength) of the narrowband filter is obtained through experimental measurement data, which is usually Gaussian distribution. For example, the light transmission curve of the filter with a center wavelength of 514 nm and a bandwidth of 1 nm can be expressed as: ; wherein, is the bandwidth parameter.

[0048] S412, measure the impurity characteristic spectral line distribution.

[0049] Specifically, the radiation intensity distribution of the impurity characteristic spectral line (such as CII 514 nm) is measured by a spectrometer , which is also usually Gaussian distribution, expressed as: ; wherein, is the center wavelength of the spectral line, is the half-width caused by Doppler broadening.

[0050] S413, calculate the correction factor; Specifically, the transmittance curve of the filter is normalized and overlaid with the spectral line distribution, and a correction factor is calculated. The correction factor is adopted using... C The calculation model is as follows: ; The corrected radiation intensity is: .

[0051] Combination Figure 5 The steps for absolute calibration of plasma images are as follows: S421. A standard light source (such as an integrating sphere) is used as a known power light source, and its radiation is imaged onto the detector after passing through the optical path structure and narrowband filter.

[0052] S422. Based on the comparison between the detector's measured intensity and the known light source, the absolute calibration coefficients of the impurity characteristic spectral lines are obtained; S423. By changing different characteristic wavelengths, the comparative calibration coefficients of different impurity spectral lines are obtained.

[0053] In this embodiment, a standard light source is placed in the optical path, and its radiant power is known. and spectral distribution The detector measured the signal. Then the calibration coefficient for: .

[0054] In actual measurements, the absolute radiation intensity of the impurity is: .

[0055] S50. The corrected plasma image is divided into grids and subjected to tomographic inversion to obtain a spatial distribution map of impurities.

[0056] Combination Figure 6 As is known, since the system uses tangential observation and each pixel measures an integral signal, mathematical tools are needed for tomographic inversion to obtain the spatial distribution of impurities. The field of view of the visible integrated optical imaging system is divided into a cubic grid. Assuming that impurity radiation is equal in each grid and symmetrical in the circumferential direction, the three-dimensional tomographic inversion can be simplified to a two-dimensional inversion on the plasma poloidal section. With technological advancements, detector pixel counts are increasing, meaning detection signals are becoming increasingly higher. Two-dimensional tomographic inversion can then be directly solved using the least squares method to give the two-dimensional spatial distribution of impurities. This method effectively overcomes the inversion difficulties caused by the complex magnetic topology of the divertor region, achieving high spatial resolution measurement of impurity distribution at the plasma edge.

[0057] In this embodiment, the grid division method is to divide the area within the field of view of the visible light imaging system into a cubic grid, and assume that the impurity radiation in each grid is equal, wherein the impurity radiation is symmetrical in the circumferential direction.

[0058] Accordingly, the tomographic inversion method is to perform tomographic inversion using the least squares method, simplifying the three-dimensional tomographic inversion into a two-dimensional inversion on the plasma poloidal section, thereby obtaining the spatial distribution map of impurities. Figure 7 ).

[0059] Therefore, by analyzing the obtained two-dimensional impurity spatial distribution map, the distribution of impurities in the divertor region can be clearly shown, providing an important basis for studying impurity transport mechanisms and optimizing plasma performance.

[0060] Specifically, in this embodiment, the meshing method is as follows: the divertor region is divided into... N × N A polar grid (e.g., 50x50) is used, and each grid is assumed to be... The impurity radiation intensity is Based on this, each pixel of the detector P The measured value is then the line integral along the line of sight: .in, This is a weight matrix, representing the pixel points. P With grid geometric relationships, It is noise.

[0061] In this embodiment, the tomographic inversion uses the least squares method. When constructing the linear equation system, the measured values ​​are... and unknown quantities Represented in matrix form: ,in, Let be the projection matrix. Then, solve for the solution by minimizing the sum of squared residuals. : Then, a regularization term is added to avoid ill-conditioned solutions. Thus, Where α is a hyperparameter, determined through cross-validation. Finally, the inverted result... The impurity concentration gradient and the high-radiation region near point X are mapped to a two-dimensional distribution map of the poloidal section, and the spatial distribution map of the impurities is obtained by marking the impurity concentration gradient and the high-radiation region near point X.

[0062] based on Figure 7 As shown in Table 1, a high concentration of carbon impurities (CII) appears near the inner target plate, which may be related to the material erosion phase. At the same time, the radiation intensity below point X is low, indicating that the magnetic field configuration has a suppressive effect on impurity transport.

[0063] Table 1 In summary, the method for measuring two-dimensional distribution of impurities in the divertor region of a nuclear fusion device provided by the embodiment can obtain high spatial resolution impurity distribution by collecting plasma radiation image data through a visible light imaging system, which helps to more finely study the impurity transport mechanism in the edge region. After the plasma image is collected, the plasma image is corrected and absolutely calibrated to ensure the accuracy of the measurement data. Finally, the corrected plasma image is divided into grids and tomographically inverted to obtain the spatial distribution of impurities.

[0064] Compared with the vacuum ultraviolet imaging method, the visible light imaging system does not need a long vacuum light collection pipeline, and the system design and operation are more simple and convenient. Moreover, the visible light imaging system is suitable for various magnetic confinement nuclear fusion devices and is not sensitive to the complex magnetic topology structure of the divertor region, so the measurement result is more accurate and reliable. The method can help to control the heat load in the fusion reactor, study the material erosion and fuel retention phenomenon, and optimize the design of the fusion reactor, especially in the selection of divertor and wall materials and the design of geometric structure, thereby meeting the important technical requirements of efficient fusion reaction and long-term stable operation of the device.

[0065] In summary, the method for measuring two-dimensional distribution of impurities in the divertor region of a nuclear fusion device provided by the embodiment can obtain high spatial resolution impurity distribution by collecting plasma radiation image data through a visible light imaging system, which helps to more finely study the impurity transport mechanism in the edge region. After the plasma image is collected, the plasma image is corrected and absolutely calibrated to ensure the accuracy of the measurement data. Finally, the corrected plasma image is divided into grids and tomographically inverted to obtain the spatial distribution of impurities.

[0066] Meanwhile, the method for measuring two-dimensional distribution of impurities in the divertor region of a nuclear fusion device provided by the embodiment can help to control the heat load in the fusion reactor by accurately measuring the impurity distribution in the divertor region. The method can also be used to study the material erosion and fuel retention phenomenon, which is crucial for understanding and controlling the material degradation and fuel circulation in the fusion reactor. The method can be used to optimize the design of the fusion reactor, especially in the selection of divertor and wall materials and the design of geometric structure.

[0067] In addition, the present application is described according to the flowchart and / or block diagram of the method, device (system), and computer program product of the embodiment. It should be understood that each flow and / or block in the flowchart and / or block diagram, and the combination of the flows 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 the 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 produce a device that implements the functions specified in the flowchart and / or block diagram. Figure 1 The device that implements the functions specified in the flowchart and / or block diagram. Figure 1 The device that implements the functions specified in the flowchart and / or block diagram.

[0068] These computer program instructions can also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instructions which implement the flow Figure 1 one or more flows and / or blocks Figure 1 one or more blocks or multiple blocks.

[0069] These computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the flow Figure 1 one or more flows and / or blocks Figure 1 one or more blocks or multiple blocks.

[0070] Those of ordinary skill in the art can understand that all or part of the steps of the above-mentioned facts and methods can be completed by programs instructing relevant hardware, and the programs involved or the programs mentioned can be stored in a computer-readable storage medium. When the program is executed, it includes the following steps: at this time, the corresponding method steps are derived, and the storage medium can be ROM / RAM, a magnetic disc, an optical disc, etc.

[0071] The above detailed description of the specific embodiments of the present application has further detailed the purposes, technical solutions and beneficial effects of the present application. It should be understood that the above description is only a specific embodiment of the present application and is not used to limit the protection scope of the present application. Any modification, equivalent replacement, improvement, etc. within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A method for measuring a two-dimensional distribution of impurities in a divertor region of a nuclear fusion device, characterized by, The method comprises the following steps: Collecting plasma radiation image data by a visible light imaging system; Correcting and absolutely calibrating the plasma image; Grid dividing and tomographic inversion of the corrected plasma image to obtain the spatial distribution of impurities.

2. The method according to claim 1, wherein the method is characterized by: The method further comprises the following steps: Installing the visible light imaging system so that it can cover the whole area of the divertor.

3. The method according to claim 2, wherein the method is characterized by: The visible light imaging system is installed at the X point of the divertor and performs tangential observation.

4. The method according to claim 3, wherein the method is characterized by: The imaging plane of the visible light imaging system coincides with the detector.

5. The method according to claim 4, wherein the method is characterized by: A narrow-band filter is installed between the imaging light path of the visible light imaging system and the detector.

6. The method according to claim 5, wherein the method is characterized by: The central wavelength of the narrow-band filter is 514 nm and the bandwidth is 1 nm.

7. The method according to claim 5, wherein the method is characterized by: The method for correcting the plasma image is to normalize the light transmission curve of the narrow-band filter and the distribution of impurity characteristic spectral lines.

8. The method according to claim 5, wherein the method is characterized by: The step for absolutely calibrating the plasma image is: Using a standard light source as a known power light source, which is imaged on the detector after passing through the light path structure and the narrow-band filter; According to the measured intensity of the detector and the known light source, the absolute calibration coefficient of the impurity characteristic spectral line is obtained; Changing different characteristic wavelengths to obtain the comparative calibration coefficient of different impurity spectral lines.

9. The method according to any one of claims 1 to 8, wherein the method is a method for measuring a two-dimensional distribution of impurities in a divertor region of a nuclear fusion device. The grid dividing method is to divide the area in the field of view of the visible light imaging system into cubic grids and assume that the radiation of impurities in each grid is equal, wherein the impurity radiation is symmetrical in the toroidal direction.

10. The method according to claim 9, wherein the method is a method for measuring a two-dimensional distribution of impurities in a divertor region of a nuclear fusion device. The tomographic inversion method is to use the least square method for tomographic inversion, which simplifies the three-dimensional tomographic inversion into two-dimensional inversion on the plasma poloidal cross section to obtain the spatial distribution of impurities.

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