A method for real-time in-situ online contactless measurement of a magnetic field at a surface of a first wall material

Abstract

The application provides a method for real-time in-situ online non-contact measurement of a magnetic field on a surface of a first wall material, comprising the following steps: a high-energy nanosecond pulse laser ablation is used to ablate the first wall material in different magnetic field intensity areas and generate laser plasma by using an endoscope structure; the laser plasma radiates a spectral signal with wall element characteristic information during a cooling process; an optical collection system with an endoscope structure is used to collect laser plasma radiation light and couple the collected plasma radiation light to a multicore optical fiber; the collected plasma radiation light is coupled to a spectrometer; spectral data are transmitted to a computer for analysis by using the spectrometer; a splitting distance and a spatial distribution characteristic of a spectral characteristic peak under different magnetic field intensities are extracted and compared with standard spectra under different directions and different magnetic field intensities in an established database to screen a standard spectrum with the highest correlation coefficient; a magnetic field intensity and a direction corresponding to the standard spectrum are found in the database and displayed to realize measurement of the magnetic field intensity and the direction.

Description

Technical Field

[0001] This invention relates to the field of magnetic field measurement technology, and more particularly to a method for real-time, in-situ, online, non-contact measurement of the magnetic field on the surface of a first wall material. Background Technology

[0002] In magnetically confined fusion devices such as tokamaks, the central solenoid and heating field coils form an ohmic transformer to heat the fuel, generating plasma and forming a plasma current. Simultaneously, a circumferential magnetic field is generated within the longitudinal field coils distributed along the annular direction of the vacuum chamber. The poloidal magnetic field and the circumferential magnetic field generated by the plasma current form a superimposed magnetic field, thus achieving plasma confinement. In experimental research of plasma physics, various diagnostic systems are needed to measure various parameters of high-temperature plasma, such as plasma density, current, ion and electron temperatures, and magnetic fields. Among these parameters, measuring the tokamak magnetic field distribution is crucial for plasma control. Furthermore, charged particles in the plasma undergo Larmor cyclotron motion around magnetic field lines, and the direction of the magnetic field significantly influences the plasma state. Recent studies have found that the magnetic field direction has a substantial impact on the LH conversion power threshold, divertor asymmetry, and energy confinement level. Real-time understanding of the tokamak boundary magnetic field strength and direction is essential for correcting boundary particle transport models. Therefore, a method is needed to develop a method for real-time acquisition of the magnetic field strength and direction in different regions of the first wall surface of a magnetically confined fusion device.

[0003] On the other hand, due to the incomplete confinement of particles by the magnetic field, the high heat flux and particle flux released from the high-temperature plasma in the core generate strong plasma-wall interaction (PWI) between the plasma-facing components (PFCs). Real-time acquisition of dynamic information on the elemental composition of the first wall, especially the divertor surface, is crucial for understanding the physical processes of PWI and optimizing experimental conditions for long-pulse, high-parameter plasmas. Laser-induced breakdown spectroscopy (LIBS) is a non-contact, in-situ, online elemental analysis technique that enables rapid real-time detection of multiple elements. The working principle of LIBS is to focus a high-energy pulsed laser beam onto the surface of the first wall to ablate the wall material, generating transient high-temperature, high-density plasma. The emission spectrum during the cooling process of the excited plasma is then acquired and analyzed using various optical detectors, enabling qualitative and quantitative analysis of the elements in the sample. However, given the complex operating conditions of the tokamak, the varying magnetic field strength and direction in different regions have a significant impact on LIBS analysis. Therefore, obtaining the magnetic field strength information of the wall surface simultaneously with acquiring the LIBS signal can calibrate the quantitative and qualitative analysis results, thereby improving the accuracy of the LIBS analysis results.

[0004] Currently, the main methods for measuring the strength and direction of the magnetic field in the first wall are the magnetic probe method and the Hall probe method. The magnetic probe method, as a diagnostic method that can measure the strength and direction of the magnetic field in the first wall in real time, in situ, and online, is currently used in various fusion devices worldwide. However, as an invasive diagnostic method, it inevitably interferes with the plasma, and it can generally only perform local measurements, not large-scale measurements. The Hall probe method has good accuracy for static magnetic fields, but it is not suitable for installation in a vacuum chamber.

[0005] Experimental analysis results show that the splitting distance and spatial distribution characteristics of the elemental characteristic lines in LIBS spectra are highly correlated with the surface magnetic field strength and direction of the measured first wall region. By establishing a database and related models of the elemental characteristic lines of the first wall material with different directions and magnetic field strengths, accurate measurement of the surface magnetic field strength and direction of the first wall region can be achieved using LIBS technology. Through an endoscopic structure and a laser focusing system, LIBS can achieve large-scale measurements of different regions of the first wall component. Furthermore, as a purely spectroscopic technique, LIBS technology enables real-time, in-situ, online, non-contact measurement of the first wall. Summary of the Invention

[0006] To address the aforementioned technical problems, a method for real-time, in-situ, online, non-contact measurement of the magnetic field on the surface of a first wall material is provided. The technical means employed in this invention are as follows:

[0007] A method for real-time, in-situ, online, non-contact measurement of the magnetic field on the surface of a first wall material includes:

[0008] A high-energy nanosecond pulsed laser with an endoscope structure ablates the first wall material in regions with different magnetic field intensities and generates laser plasma. During the cooling process, the laser plasma radiates spectral signals with characteristic information of the wall elements.

[0009] An optical collection system with an endoscope structure is used to collect laser plasma radiation light and couple it to a multi-core optical fiber, and then the collected plasma radiation light is coupled to a spectrometer.

[0010] Spectral data is transmitted from the spectrometer to the computer for analysis. The splitting distance and spatial distribution characteristics of the spectral characteristic peaks under different magnetic field intensities are extracted and compared with standard spectra under different directions and magnetic field intensities in the established database. The standard spectrum with the highest correlation coefficient is selected. The magnetic field intensity and direction corresponding to the selected standard spectrum are found in the database and displayed, thereby realizing the measurement of magnetic field intensity and direction.

[0011] Furthermore, the high-energy nanosecond pulsed laser employing an endoscopic structure ablates the first wall material in regions with different magnetic field intensities and generates laser plasma. During the cooling process, the laser plasma radiates spectral signals carrying characteristic information of the wall elements, including:

[0012] The data acquisition and analysis computer and digital pulse delay generator are in normal communication with the two-dimensional precision stepper motor and antimagnetic rotary motor, and the high-energy nanosecond pulse laser and high-resolution spectrometer are in external triggering state.

[0013] After determining the detection position of the first wall, the data acquisition and analysis computer sends commands to the digital pulse delay generator, the two-dimensional precision stepper motor, and the antimagnetic rotary motor, respectively.

[0014] After receiving the command, the two-dimensional precision stepper motor and the antimagnetic rotary motor move to their respective positions so that the laser can be focused onto the specific surface of the first wall material.

[0015] After receiving the trigger signal, the digital pulse delay generator triggers the high-energy nanosecond pulse laser to emit laser light and the spectrometer to receive the laser plasma radiation light signal according to the set timing sequence.

[0016] Furthermore, the optical collection system utilizing an endoscope structure collects the laser plasma radiation light and couples it to a multi-core optical fiber, then couples the collected plasma radiation light to a spectrometer, comprising:

[0017] Upon receiving the trigger signal, the high-energy nanosecond pulsed laser emits a high-energy nanosecond pulsed laser, which is reflected by the first laser high-threshold reflector, the second laser high-threshold reflector, and the third laser high-threshold reflector to adjust the laser direction and continue to propagate.

[0018] The high-energy nanosecond pulsed laser, after being reflected by the third high-threshold laser reflector, passes through the first optical aperture and the second optical aperture to achieve beam collimation. At the same time, the red indicator light emitted by the helium-neon laser indicator is adjusted to pass through the first optical aperture and the second optical aperture to achieve coaxiality with the laser beam.

[0019] The collimated high-energy nanosecond pulse laser and the red indicator light are expanded by a first-stage beam expander, then reflected by a dichroic mirror and continue to propagate.

[0020] The high-energy nanosecond pulse laser and the red indicator light continue to propagate forward. After being reflected by the aluminum film mirror, they are further expanded by a two-stage beam expander composed of concave and convex lenses. At the same time, a two-dimensional precision stepper motor drives the concave lens to move to achieve focusing, thereby ensuring that the high-energy nanosecond pulse laser can detect different areas of the first wall.

[0021] The high-energy nanosecond pulsed laser and the red indicator light, which are expanded again, are reflected by the aluminum film reflector and enter the endoscope tube. After being focused by the laser focusing lens, they are reflected by the endoscope onto the sample to be tested or the surface of the first wall. At the same time, the endoscope is rotated by a precision rotating motor to realize the detection of different areas of the first wall by the high-energy nanosecond pulsed laser.

[0022] A red indicator light is focused onto the surface of the first wall to determine the detection position; the focusing size of the high-energy nanosecond pulse laser is controlled by a focusing system composed of concave and convex lenses to achieve the required millimeter-level spatial resolution.

[0023] A high-energy nanosecond pulsed laser is focused onto the surface of the sample or the first wall, and ablation excitation is performed to form transient laser plasma.

[0024] After being reflected by the endoscope, the transient laser plasma returns along its original path, passing through a laser focusing lens, an aluminum film reflector, a convex lens, a concave lens, an aluminum film reflector, and a dichroic mirror, before being focused by an achromatic lens into a multi-core linear array fiber.

[0025] Furthermore, the spectral data is transmitted from the spectrometer to a computer for analysis. The splitting distance and spatial distribution characteristics of spectral characteristic peaks under different magnetic field intensities are extracted and compared with standard spectra in different directions and under different magnetic field intensities in an established database. The standard spectra with the highest correlation coefficients are then selected, including:

[0026] Multi-core linear array fiber transmits the collected laser plasma radiation light to a spectrometer equipped with an ICCD camera, thereby achieving spatial resolution and signal enhancement;

[0027] The spectrometer synchronously transmits the collected laser plasma radiation spectrum signals to the data acquisition and analysis computer;

[0028] The data acquisition and analysis computer analyzes in real time the fracture distance and spatial distribution characteristics of the plasma radiation spectrum under different magnetic field intensities.

[0029] By comparing the splitting distance and spatial distribution characteristics of spectral feature lines under different magnetic field intensities analyzed in real time by the data acquisition and analysis computer with the standard spectra under different magnetic field intensities in the established database, the standard spectrum with the highest correlation coefficient is selected, and the corresponding magnetic field intensity and direction of the standard spectrum are found in the database and displayed.

[0030] Furthermore, the spectrometer is a high-resolution spectrometer, and the multi-core optical fiber is a linear array optical fiber.

[0031] Compared with the prior art, the present invention has the following advantages:

[0032] 1. The method for real-time in-situ online non-contact measurement of the magnetic field on the surface of the first wall material provided by the present invention can realize real-time, in-situ online, non-contact, active, and high spatial (mm-level) resolution measurement of the magnetic field on the surface of the first wall component.

[0033] 2. The method for real-time in-situ online non-contact measurement of the magnetic field on the surface of the first wall material provided by the present invention requires the spectrometer to collect transient laser plasma radiation light with a relatively long gate delay under the premise of ensuring sufficient signal, thereby reducing the Stark broadening of the spectrum and obtaining a more accurate Zeeman split of the characteristic line, thus improving the accuracy of magnetic field strength analysis of this technology.

[0034] 3. The method for real-time in-situ online non-contact measurement of the magnetic field on the surface of the first wall material provided by this invention achieves coaxiality between the ablation laser and the collected transient laser plasma radiation light through an endoscope, thereby improving the stability and flexibility of the system. Simultaneously, the use of an endoscope effectively utilizes the very limited optical window of the tokamak to achieve a large-scale spatial scan of the first wall surface.

[0035] 4. The method for real-time in-situ online non-contact measurement of the magnetic field on the surface of the first wall material provided by the present invention integrates the entire complex optical system on a 600mm*1000mm optical platform by combining multiple reflectors to cope with the harsh actual working conditions of the tokamak.

[0036] Based on the above reasons, this invention can be widely applied in fields such as magnetic field measurement. Attached Figure Description

[0037] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0038] Figure 1 This is a flowchart illustrating the method for real-time in-situ online non-contact measurement of the magnetic field on the surface of the first wall material provided by the present invention.

[0039] Figure 2 This is a schematic diagram of the structure of the method for real-time in-situ online non-contact measurement of the magnetic field on the surface of the first wall material provided by the present invention.

[0040] Figure 3 This is a schematic diagram of Zeeman splitting of the characteristic lines of molybdenum atoms under a Tesla magnetic field, provided for an embodiment of the present invention.

[0041] Figure 4 This is a schematic diagram of the characteristic lines of molybdenum atoms in the absence of a magnetic field, provided in an embodiment of the present invention.

[0042] In the diagram: 1. Data acquisition and analysis computer; 2. Digital pulse delay generator; 3. High-energy nanosecond pulse laser; 4. First high-threshold laser mirror; 5. Second high-threshold laser mirror; 6. Third high-threshold laser mirror; 7. Helium-neon laser pointer; 8. First optical aperture stop; 9. Second optical aperture stop; 10. First-stage beam expander; 11. Dichroic mirror; 12. Aluminum film mirror; 13. Concave lens; 14. Two-dimensional precision stepper motor; 15. Convex lens; 16. Aluminum film mirror; 17. Laser focusing lens; 18. Endoscope; 19. Rotary precision motor; 20. First wall surface; 21. Transient laser plasma; 22. Achromatic lens; 23. Multi-core linear array fiber; 24. Spectrometer equipped with ICCD camera. Detailed Implementation

[0043] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0044] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0045] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0046] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps described in these embodiments do not limit the scope of the invention. It should also be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following figures denote similar items; therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0047] In the description of this invention, it should be understood that the orientation or positional relationship indicated by directional terms such as "front, back, up, down, left, right", "horizontal, vertical, horizontal" and "top, bottom" is generally based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing this invention and simplifying the description. Unless otherwise stated, these directional terms do not indicate or imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the scope of protection of this invention. The directional terms "inner" and "outer" refer to the inner and outer contours relative to the outline of each component itself.

[0048] For ease of description, spatial relative terms such as "above," "over," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation besides the orientation of the device as described in the figures. For example, if the device in the figures is inverted, a device described as "above" or "above" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.

[0049] Furthermore, it should be noted that the use of terms such as "first" and "second" to define components is merely for the purpose of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore should not be construed as limiting the scope of protection of this invention.

[0050] like Figure 1 As shown, this invention provides a method for real-time in-situ online non-contact measurement of the magnetic field on the surface of a first wall material, comprising the following six steps:

[0051] Step 1: The timing control system is in place;

[0052] Step 2: Laser ablation of wall materials under different magnetic field intensities;

[0053] Step 3: Coaxially collect laser plasma signals under different magnetic field intensities;

[0054] Step 4: The spectrometer signal is synchronized to the computer for processing to obtain the characteristic spectral line splits and spatial distribution characteristics;

[0055] Step 5: Compare with the established database to find the corresponding standard spectrum;

[0056] Step 6: The computer outputs the magnetic field strength and direction of the wall surface.

[0057] The principle of this invention is as follows:

[0058] The characteristic spectral lines of elements radiated by the transient plasma from laser ablation under the strong magnetic field at the boundary of the tokamak undergo Zeeman splitting, such as... Figure 3 , 4 As shown, the relationship between the crack distance and the strength of the boundary magnetic field is as follows:

[0059]

[0060] In the formula, Δλ B The wavelength displacement corresponding to the splitting moment, e is the elementary charge, λ0 is the wavelength without an external magnetic field, B is the magnetic field strength, and m e Let be the electron mass and c be the speed of light. It is evident that the split distance is proportional to the strength of the boundary magnetic field.

[0061] Simultaneously, charged particles such as positive ions undergo Larmor cyclotron motion under the Lorentz force in a magnetic field. The equation is as follows:

[0062]

[0063] In the formula, m is the particle mass, v is the particle velocity, q is the charge number, and B is the magnetic field strength. The acceleration of transient plasma under a laser electric field causes charged particles to undergo E×B drift, and different magnetic field directions result in significant differences in the spatial distribution characteristics of the plasma.

[0064] To accurately analyze the magnetic field information of the first wall surface, it is necessary to establish LIBS standard spectra of the first wall material under different magnetic field intensities and directions. This involves classifying the standard spectra and establishing functional relationships and judgment criteria with magnetic field intensity and direction.

[0065] Based on the above principles, such as Figure 2 The schematic diagram of the device structure details the specific implementation scheme of the method of the present invention:

[0066] S1. A high-energy nanosecond pulsed laser with an endoscope structure ablates the first wall material in regions with different magnetic field intensities and generates laser plasma. During the cooling process, the laser plasma radiates a spectral signal with characteristic information of the wall elements.

[0067] S2. The laser plasma radiation light is collected by an optical collection system with an endoscope structure and coupled to a multi-core optical fiber. The collected plasma radiation light is then coupled to a spectrometer.

[0068] S3. The spectral data is transmitted from the spectrometer to the computer for analysis. The splitting distance and spatial distribution characteristics of the spectral characteristic peaks under different magnetic field intensities are extracted and compared with the standard spectra under different directions and different magnetic field intensities in the established database. The standard spectrum with the highest correlation coefficient is selected. The magnetic field intensity and direction corresponding to the selected standard spectrum are found in the database and displayed, thereby realizing the measurement of magnetic field intensity and direction.

[0069] In a specific implementation, as a preferred embodiment of the present invention, step S1 specifically includes:

[0070] The data acquisition and analysis computer 1 and the digital pulse delay generator 2 are in normal communication with the two-dimensional precision stepper motor 14 and the antimagnetic rotary motor 19, and the high-energy nanosecond pulse laser 3 and the high-resolution spectrometer 24 are in external triggering state.

[0071] After determining the detection position of the first wall, the data acquisition and analysis computer 1 sends commands to the digital pulse delay generator 2, the two-dimensional precision stepper motor 14 and the antimagnetic rotary motor 19 respectively;

[0072] After receiving the command, the two-dimensional precision stepper motor 14 and the antimagnetic rotary motor 19 move to their respective positions so that the laser can be focused onto the specific surface of the first wall material.

[0073] After receiving the trigger signal, the digital pulse delay generator 2 triggers the high-energy nanosecond pulse laser 3 to emit laser light and the spectrometer to receive the laser plasma radiation light signal according to the set timing sequence.

[0074] In a specific implementation, as a preferred embodiment of the present invention, step S2 specifically includes:

[0075] Upon receiving the trigger signal, the high-energy nanosecond pulse laser 3 emits a high-energy nanosecond pulse laser, which is reflected by the first high-threshold laser mirror 4, the second high-threshold laser mirror 5, and the third high-threshold laser mirror 6 to adjust the laser direction and continue propagating. The adjustment of the laser direction by the high-threshold laser mirror can effectively prevent the laser from being reflected back to the laser, thereby protecting the laser, and can also effectively reduce the space occupied by the instrument.

[0076] The high-energy nanosecond pulsed laser, after being reflected by the third high-threshold laser reflector 6, passes through the first optical aperture 8 and the second optical aperture 9 to achieve beam collimation. At the same time, the red indicator light emitted by the helium-neon laser indicator 7 is adjusted to pass through the first optical aperture 8 and the second optical aperture 9 to achieve coaxiality with the laser beam. The high-energy nanosecond pulsed laser used in this invention has a fundamental frequency of 1064nm, which is invisible to the human eye. The use of the red indicator light can effectively improve the optical path adjustment efficiency of the entire system.

[0077] The collimated high-energy nanosecond pulsed laser and the red indicator light are expanded by the first-stage beam expander 10 and then reflected by the dichroic mirror 11 before continuing to propagate. Expanding the beam before focusing the high-energy nanosecond pulsed laser during long-distance transmission effectively improves the focusing quality of the light spot. The dichroic mirror 11 can reflect the high-energy nanosecond pulsed laser with a fundamental frequency of 1064 nm and transmit plasma radiation light of 350–900 nm, thereby achieving coaxial signal collection.

[0078] The high-energy nanosecond pulse laser and the red indicator light continue to propagate forward. After being reflected by the aluminum film reflector 12, they are further expanded by a secondary beam expander composed of a concave lens 13 and a convex lens 15. At the same time, the concave lens 13 is moved by the two-dimensional precision stepper motor 14 to achieve focusing, thereby ensuring that the high-energy nanosecond pulse laser can detect different areas (different distances) of the first wall. The aluminum film reflector can simultaneously reflect the high-energy nanosecond pulse laser with a fundamental frequency of 1064nm and the plasma radiation light of 350–900nm.

[0079] The high-energy nanosecond pulse laser and the red indicator light, which are expanded again, are reflected by the aluminum film reflector 16 and enter the endoscope tube 25. After being focused by the laser focusing lens 17, they are reflected by the endoscope 18 onto the sample to be tested or the surface 20 of the first wall. At the same time, the endoscope 18 is rotated by the rotary precision motor 19 to realize the detection of different areas of the first wall by the high-energy nanosecond pulse laser.

[0080] The red indicator light is focused onto the first wall surface 20 to determine the detection position; the focusing size of the high-energy nanosecond pulse laser is controlled by a focusing system composed of a concave lens 13 and a convex lens 15 to achieve the required millimeter-level spatial resolution.

[0081] A high-energy nanosecond pulsed laser is focused onto the sample under test or the surface 20 of the first wall, and ablation excitation is performed to form transient laser plasma 21.

[0082] The transient laser plasma 21, after being reflected by the endoscope 18, returns along its original path, passing through the laser focusing lens 17, aluminum film reflector 16, convex lens 15, concave lens 13, aluminum film reflector 12, and dichroic mirror 11, before being focused by the achromatic lens 22 into the multi-core linear array optical fiber 23. In this embodiment, the spectrometer is a high-resolution spectrometer, better than 0.01 nm, and the multi-core optical fiber is a linear array optical fiber.

[0083] In a specific implementation, as a preferred embodiment of the present invention, step S3 specifically includes:

[0084] The multi-core linear array fiber 23 transmits the collected laser plasma radiation light to the spectrometer 24 equipped with an ICCD camera, thereby achieving spatial resolution and signal enhancement.

[0085] The spectrometer 24 synchronously transmits the collected laser plasma radiation spectrum signal to the data acquisition and analysis computer 1;

[0086] The data acquisition and analysis computer 1 analyzes in real time the fracture distance and spatial distribution characteristics of the plasma radiation spectrum under different magnetic field intensities.

[0087] By comparing the splitting distance and spatial distribution characteristics of spectral feature lines under different magnetic field intensities analyzed in real time by the data acquisition and analysis computer 1 with the standard spectra under different magnetic field intensities in the established database, the standard spectrum with the highest correlation coefficient is selected, and the corresponding magnetic field intensity and direction of the standard spectrum are found in the database and displayed.

[0088] In summary, the real-time, in-situ, online, non-contact measurement method for the surface magnetic field of the first wall material provided by this invention utilizes laser-induced breakdown spectroscopy to achieve a large-scale scan of the first wall material, obtaining magnetic field strength and direction information at different locations. This method is applicable to the complex operating environment of tokamaks, offers flexible operation, and is a real-time, in-situ, online, non-contact measurement method. This invention is primarily used in fields such as the measurement of the surface magnetic field of the first wall material in tokamaks, but its application to other technical fields with similar technical features requiring large-scale magnetic field measurements is not excluded.

[0089] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for real-time, in-situ, online, non-contact measurement of the magnetic field on the surface of a first wall material, characterized in that, include: A high-energy nanosecond pulsed laser with an endoscope structure ablates the first wall material in regions with different magnetic field intensities and generates laser plasma. During the cooling process, the laser plasma radiates spectral signals with characteristic information of the wall elements. An optical collection system with an endoscopic structure is used to collect laser plasma radiation and couple it to a multi-core optical fiber. The collected plasma radiation is then coupled to a spectrometer, including: Upon receiving the trigger signal, the high-energy nanosecond pulse laser (3) emits a high-energy nanosecond pulse laser, which is reflected by the first high-threshold laser mirror (4), the second high-threshold laser mirror (5), and the third high-threshold laser mirror (6) to adjust the laser direction and continue to propagate. The high-energy nanosecond pulse laser after being reflected by the third high-threshold laser mirror (6) passes through the first optical aperture (8) and the second optical aperture (9) to achieve beam collimation. At the same time, the red indicator light emitted by the helium-neon laser indicator (7) is adjusted to pass through the first optical aperture (8) and the second optical aperture (9) to achieve coaxiality with the laser beam. The collimated high-energy nanosecond pulse laser and red indicator light are expanded by a first-stage beam expander (10), then reflected by a dichroic mirror (11) and continue to propagate; The high-energy nanosecond pulse laser and the red indicator light continue to propagate forward. After being reflected by the aluminum film reflector (12), they are further expanded by a secondary beam expander composed of a concave lens (13) and a convex lens (15). At the same time, the concave lens (13) is moved by a two-dimensional precision stepper motor (14) to achieve focusing, thereby ensuring that the high-energy nanosecond pulse laser can detect different areas of the first wall. The high-energy nanosecond pulse laser and the red indicator light, which are expanded again, are reflected by the aluminum film reflector (16) and enter the endoscope tube (25). After being focused by the laser focusing lens (17), they are reflected by the endoscope (18) onto the surface (20) of the first wall. At the same time, the antimagnetic rotary motor (19) drives the endoscope (18) to rotate so as to realize the detection of different areas of the first wall by the high-energy nanosecond pulse laser. The red indicator light is focused onto the first wall surface (20) to determine the detection position; the focusing size of the high-energy nanosecond pulse laser is controlled by a focusing system composed of a concave lens (13) and a convex lens (15) to achieve the required millimeter-level spatial resolution. A high-energy nanosecond pulsed laser is focused onto the surface of the first wall (20) to ablate and excite transient laser plasma (21). The transient laser plasma (21) is reflected by the endoscope (18) and returns along the original path. It passes through the laser focusing lens (17), aluminum film mirror (16), convex lens (15), concave lens (13), aluminum film mirror (12), and dichroic mirror (11) respectively, and is then focused into the multi-core linear array fiber (23) by the achromatic lens (22). Spectral data is transmitted from the spectrometer to the computer for analysis. The splitting distance and spatial distribution characteristics of the spectral characteristic peaks under different magnetic field intensities are extracted and compared with standard spectra under different directions and magnetic field intensities in the established database. The standard spectrum with the highest correlation coefficient is selected. The magnetic field intensity and direction corresponding to the selected standard spectrum are found in the database and displayed, thereby realizing the measurement of magnetic field intensity and direction.

2. The method for real-time in-situ online non-contact measurement of the magnetic field on the surface of the first wall material according to claim 1, characterized in that, The high-energy nanosecond pulsed laser employing an endoscopic structure ablates the first wall material in regions with different magnetic field intensities, generating laser plasma. During the cooling process, the laser plasma radiates spectral signals carrying characteristic information of the wall elements, including: The data acquisition and analysis computer (1) and digital pulse delay generator (2) are in normal communication with the two-dimensional precision stepper motor (14) and antimagnetic rotary motor (19), and the high-energy nanosecond pulse laser (3) and high-resolution spectrometer (24) are in external triggering state. After determining the detection position of the first wall, the data acquisition and analysis computer (1) sends commands to the digital pulse delay generator (2), the two-dimensional precision stepper motor (14), and the antimagnetic rotary motor (19), respectively. After receiving the command, the two-dimensional precision stepper motor (14) and the antimagnetic rotary motor (19) move to their respective positions so that the laser can be focused onto the surface of the specific first wall material. After receiving the trigger signal, the digital pulse delay generator (2) triggers the high-energy nanosecond pulse laser (3) to emit laser light and the spectrometer to receive the laser plasma radiation light signal according to the set timing sequence.

3. The method for real-time in-situ online non-contact measurement of the magnetic field on the surface of the first wall material according to claim 1, characterized in that, The spectral data is transmitted from the spectrometer to a computer for analysis. The splitting distance and spatial distribution characteristics of spectral characteristic peaks under different magnetic field intensities are extracted and compared with standard spectra in different directions and under different magnetic field intensities in an established database. The standard spectra with the highest correlation coefficients are then selected, including: The multi-core linear array fiber (23) transmits the collected laser plasma radiation light to the spectrometer (24) equipped with an ICCD camera, thereby achieving spatial resolution and signal enhancement; The spectrometer (24) synchronously transmits the collected laser plasma radiation spectrum signal to the data acquisition and analysis computer (1); The data acquisition and analysis computer (1) analyzes the crack distance and spatial distribution characteristics of the plasma radiation spectrum under different magnetic field intensities in real time; By comparing the splitting distance and spatial distribution characteristics of the spectral feature lines under different magnetic field intensities analyzed in real time by the data acquisition and analysis computer (1) with the standard spectra under different magnetic field intensities in the established database, the standard spectra with the highest correlation coefficient are selected, and the magnetic field intensity and direction corresponding to the standard spectra are found and displayed in the database.

4. The method for real-time in-situ online non-contact measurement of the magnetic field on the surface of the first wall material according to claim 1, characterized in that, The spectrometer is a high-resolution spectrometer, and the multi-core optical fiber is a linear array optical fiber.

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