Tokamak vacuum chamber leakage detection device and method based on multi-beam laser induction

Abstract

The invention discloses a tokamak vacuum chamber leakage detection device and a tokamak vacuum chamber leakage detection method based on multi-beam laser induction, which can perform remote, real-time and non-contact online detection on tokamak vacuum chamber leakage based on laser-induced breakdown spectroscopy (LIBS) technology. Through the synergistic effect of the diffractive optical element and the collimating lens, a single beam of high-energy pulse laser is converted into N spatially discrete parallel sub-beams, parallel detection of N point locations can be realized under single pulse excitation, and the detection efficiency is greatly improved. In addition, misjudgment possibly existing in single-point detection can be effectively eliminated through multi-point synchronous detection, and the position of the leakage point can be locked more quickly by combining the intensity distribution characteristics of the characteristic spectral lines of the leakage elements of the N point positions.

Description

Technical Field

[0001] This invention belongs to the field of vacuum leak detection technology, specifically relating to a tokamak vacuum chamber leak detection device and method based on multi-beam laser-induced leakage. Background Technology

[0002] Tokamak devices, developed based on the principle of magnetic confinement, are currently the most promising experimental devices for breaking through the bottlenecks of controlled nuclear fusion technology and realizing nuclear fusion reactor power generation. An ultra-high vacuum environment is a key condition for achieving plasma confinement and maintaining stable fusion reactions. If a vacuum leak occurs, impurity gases will enter the vacuum chamber, disrupting the vacuum conditions and diluting the plasma concentration, thereby reducing the fusion power density. Simultaneously, vacuum leaks can also cause plasma radiation loss, affecting the confinement effect and even causing plasma fragmentation, ultimately impacting the safety and efficiency of nuclear fusion experiments. Therefore, rapid detection of leaks in the tokamak vacuum chamber is crucial.

[0003] Currently, the commonly used leak detection method for tokamak devices is helium mass spectrometry (HMS). This method uses helium as a tracer gas and a helium mass spectrometer to detect helium molecules. While this method can detect minute vacuum leaks and achieve relatively precise location, it requires the tokamak device to be shut down and completely cooled before helium injection can be performed on the test area. Due to the complex structure and large size of the tokamak, leak location requires a section-by-section inspection, making the process very cumbersome and time-consuming. In future deuterium-tritium polymerization experiments, the safety issues posed by radiation must also be considered. Traditional leak detection methods require close-range inspection by researchers, which cannot guarantee their safety.

[0004] Therefore, there is an urgent need to develop a real-time, online, and remote leak detection method, which is of great significance for improving the safety and stability of tokamak operation and accelerating the nuclear fusion research process. Summary of the Invention

[0005] In view of the above-mentioned shortcomings in the prior art, the tokamak vacuum chamber leakage detection device and method based on multi-beam laser-induced leakage provided by the present invention solves the problems of cumbersome detection process and safety hazards in the existing detection methods.

[0006] To achieve the above-mentioned objectives, the technical solution adopted by the present invention is as follows: a tokamak vacuum chamber leakage detection device based on multi-beam laser-induced leakage, comprising a laser generation and shaping unit, a beam scanning and focusing unit, an optical path coupling and separation unit, and a signal collection unit arranged sequentially.

[0007] The laser generation and shaping unit, the beam scanning and focusing unit, and the optical path coupling and separation unit are arranged sequentially along the laser beam emission optical path;

[0008] The laser generation and shaping unit is used to generate a laser beam and shape it into several parallel laser beams; the beam scanning and focusing unit is used to control the deflection of the parallel laser beams in the horizontal / vertical direction and convert the angle change of the deflected laser beam into the movement of the focal position, forming an S-shaped reciprocating scanning path; the optical path coupling and separation unit is used to introduce the laser beam into the tokamak vacuum chamber for scanning and receive the reflected spectral signal.

[0009] The signal collection unit is used to collect the spectral signals reflected inside the tokamak vacuum chamber and generate a spectral map for analyzing gas leakage at the scanning point of the tokamak vacuum chamber.

[0010] Furthermore, the laser generation and shaping unit includes a pulsed laser, a beam expander, a diffractive optical element, and a collimating lens;

[0011] The laser beam generated by the pulsed laser passes sequentially through a beam expander, a diffractive optical element, and a collimating lens;

[0012] The beam expander is used to reduce the divergence angle of the laser beam and adjust the diameter of the laser beam to meet the incident requirements of the diffractive optical element.

[0013] The diffractive optical element is used to divide the laser beam into several spatially discrete sub-laser beams with uniform energy distribution.

[0014] The collimating lens is used to correct several sub-laser beams into parallel laser beams.

[0015] Furthermore, the beam expander includes a diverging lens and a third focusing lens arranged sequentially along the diverging optical path of the laser beam.

[0016] Furthermore, the beam scanning and focusing unit includes a first galvanometer, a second galvanometer, and a first focusing lens arranged sequentially in the light output path of the laser generation and shaping unit;

[0017] The first and second galvanometers are used to control the deflection angles of the parallel laser generated by the laser generator and the shaping unit in the horizontal and vertical directions, respectively.

[0018] The first focusing lens is disposed in the reflected light path of the second galvanometer to converge the deflected parallel laser beam and convert the change in the laser beam angle into a change in the focal position.

[0019] Furthermore, the first galvanometer includes a first reflector and a first drive motor, and the second galvanometer includes a second reflector and a second drive motor;

[0020] The first reflector is fixedly mounted on the shaft of the first drive motor. The first drive motor drives the first reflector to deflect, thereby controlling the deflection angle of the parallel laser in the horizontal direction.

[0021] The second reflector is fixedly mounted on the shaft of the second drive motor. The second drive motor drives the second reflector to deflect, thereby controlling the deflection angle of the parallel laser in the vertical direction.

[0022] Furthermore, the optical path coupling and separation unit includes a dichroic color and an observation window;

[0023] The observation window is located on the side wall of the tokamak vacuum chamber, and the dichroic mirror is located between the first focusing lens and the observation window in the optical path coupling and separation unit.

[0024] The optical path of the dichroic mirror includes a transmission optical path and a reflection optical path;

[0025] The transmission optical path transmits the laser beam focused by the optical path coupling and separation unit through the observation window (9) and introduces it into the tokamak vacuum chamber;

[0026] The reflected light path collects the spectral signal emitted by the plasma generated by the laser beam ablation of the inner wall surface of the tokamak vacuum chamber through the observation window and introduces it into the signal collection unit.

[0027] Furthermore, the signal collection unit is arranged on the reflected light path of the dichroic mirror in the optical path coupling and separation unit, and includes a focusing lens array, an optical fiber probe, an optical fiber, a spectrometer, an ICCD camera, a digital delay pulse generator, and a computer arranged in sequence.

[0028] The focusing lens array is used to collect the various spectral signals emitted by the optical path coupling and separation unit;

[0029] The fiber optic probe is used to couple each spectral signal to the corresponding fiber optic cable;

[0030] The optical fiber is used to transmit each spectral signal to the corresponding channel interface of the spectrometer.

[0031] The spectrometer is used to synchronously split the input spectral signal into monochromatic spectral signals distributed according to wavelength.

[0032] The ICCD camera is located at the output light interface of the spectrometer and is used to amplify the monochromatic spectral signal and convert it into a spectral electrical signal.

[0033] The digital delay pulse generator is connected to the pulse laser and the ICCD camera respectively, and is used to control the delay time between the activation of the ICCD camera and the pulse laser.

[0034] The computer is connected to the ICCD camera to receive and process spectral signals, generate spectral maps for each channel, and thus determine the gas leakage at the scanning points of the tokamak vacuum chamber.

[0035] Furthermore, the focusing lens array includes several horizontally arranged second focusing lenses, each of which spatially corresponds to a spectral signal emitted by plasma generated by laser beam ablation in a tokamak vacuum chamber, forming a one-to-one corresponding signal acquisition optical path.

[0036] A method for detecting leaks in a tokamak vacuum chamber based on multi-beam laser-induced leakage includes the following steps:

[0037] S100. Start the pulsed laser. The pulsed laser is generated and then passes through the beam expander, the diffractive optical element for beam splitting, and the collimating lens for collimation, forming N spatially discrete parallel laser beams with uniform energy distribution.

[0038] The parallel laser is deflected by controlling the rotation of the first and second galvanometers. The deflected parallel laser is then focused by the first focusing lens and transmitted through the dichroic mirror and the observation window, and focused on the lower left corner of the observation area of ​​the tokamak vacuum chamber, which is set as the scanning start position.

[0039] S200: A pulsed laser beam is triggered by a digital delay pulse generator. After passing through a dichroic mirror and an observation window, the laser beam is introduced into the inner wall of the tokamak vacuum chamber to ablate the wall material and generate plasma. The spectral signal emitted by the plasma is reversed and passed through the observation window. After being emitted by the dichroic mirror, it is coupled into the fiber optic probe by a focusing lens array and transmitted to the spectrometer through the fiber optic cable.

[0040] The delay timer starts simultaneously with the pulsed laser emitted by the digital delay pulse generator. In response to the predetermined duration, the ICCD camera is triggered to open the gate, converting the N-channel spectral signals into spectral electrical signals and transmitting them to the computer. The spectral electrical signals of the corresponding channels are then recorded, and the spectral maps of each channel are generated.

[0041] S300. Keep the second galvanometer stationary and adjust the deflection of the first galvanometer so that the focus of the N parallel laser beams on the inner wall of the tokamak vacuum chamber moves horizontally to the right in a set step.

[0042] S400, in response to the focus moving horizontally to the right to the target position, repeat S200 and S300 until the focus moves to the rightmost edge of the observation area;

[0043] S500: Keep the first galvanometer stationary, adjust the deflection of the second galvanometer so that the focus of the N parallel laser beams on the inner wall of the tokamak vacuum chamber moves vertically upward at a set interval. In response to the vertical upward movement of the focus to the target position, execute S200.

[0044] S600. Keep the second galvanometer stationary and adjust the first galvanometer to deflect in the opposite direction, so that the focus of the N parallel laser beams on the inner wall of the tokamak vacuum chamber moves horizontally to the left in a set step.

[0045] S700, in response to the focus moving horizontally to the left to the target position, repeat S200 and S600 until the focus moves to the leftmost edge of the observation area;

[0046] S800, repeat S500, S400, S500 and S700 to make the parallel laser scan the observation area of ​​the tokamak vacuum chamber in an S-shaped reciprocating path until the focus moves to the uppermost edge of the observation area of ​​the tokamak vacuum chamber, thus completing the scanning of the entire observation area.

[0047] S900: By analyzing the spectral data obtained from scanning within the observation area, the gas leakage situation at the scanning point is determined.

[0048] Furthermore, the relationship between the displacement d of the focal point on the inner wall of the tokamak vacuum chamber and the deflection angle θ of the first / second galvanometer is: d = f * θ; where f represents the focal length of the first focusing lens;

[0049] The maximum range d of the scanning area max For: d max =2 * f * θ max θ max This indicates the maximum permissible deflection angle of the first and second galvanometers, and the set step size is greater than Δd when scanning left / right. min = f * Δθ min , Δθ min This represents the minimum deflection angle increment between the first and second galvanometers;

[0050] During cyclic scanning, the working cycle T of a single scan is... cycle > T galvo + T LIBS， T galvo T represents the time required for the first / second galvanometer to deflect. LIBS This indicates the time from laser beam excitation to the ICCD camera completing spectral signal acquisition and transmission.

[0051] The beneficial effects of this invention are as follows:

[0052] This invention, based on laser-induced breakdown spectroscopy (LIBS) technology, enables remote, real-time, and non-contact online detection of leaks in tokamak vacuum chambers. Specific advantages include:

[0053] (1) Tokamak vacuum chambers are large (such as the EAST vacuum chamber with a circumference of tens of meters), and traditional single-point scanning methods are too time-consuming and cannot meet the efficiency requirements of engineering time windows. In this invention, the core combination of "diffractive optical elements + collimating lenses" is used to split a single high-energy pulsed laser into multiple spatially discrete, energy-uniform parallel sub-beams. By exciting a point of a micro-array with a single pulse, parallel detection in a physical sense is achieved. This is the primary and necessary technical choice to break through this efficiency bottleneck and make rapid surveys possible.

[0054] (2) The tokamak vacuum chamber is a fixed and immovable large device, which cannot be moved as a whole for scanning like a moving sample stage. This invention adopts a scanning system of "dual galvanometers + focusing lens". By controlling the deflection angle of the mirrors, the direction of the beam is changed, and then the lens focuses the angle change into a two-dimensional displacement of the focal point on the target surface. Through the "array-scan" method, the parallel detection array is transformed into a "movable detection brush", which is driven by the galvanometer to perform high-density, regular two-dimensional grid scanning, thereby achieving continuous coverage of the observation area without omission.

[0055] (3) By using a focusing lens array in conjunction with a multi-channel spectrometer, the spectral signals of N points were independently, synchronously, and in real time acquired and compared, ensuring the time synchronization of signal acquisition at each point and demonstrating the efficiency advantage of parallel excitation. By processing the data of these N channels synchronously by computer, the spatial distribution pattern of characteristic spectral line intensity (such as gradient and aggregation area) was analyzed to locate the leak, which is far more reliable than judging whether a single point exceeds the threshold in isolation, realizing the detection upgrade from "discovering anomalies" to "locating the source".

[0056] (4) During leak detection, the high efficiency of parallel excitation and the comprehensiveness of dynamic scanning are combined, ensuring that more areas within the observation window can be effectively detected within a limited time. This fundamentally eliminates the risk of missed detection due to sparse or fixed detection points, greatly improving the reliability of the detection results. Furthermore, the entire detection process (parallel excitation - beam scanning - synchronous acquisition) is completed remotely and automatically through optical and electrical control, without the need for any moving mechanical parts on the vacuum chamber or personnel intervention. This perfectly meets the extreme requirements of tokamak devices for system stability, safety, and remote operation. Attached Figure Description

[0057] Figure 1 The structural diagram of the tokamak vacuum chamber leakage detection device based on multi-beam laser induction provided by the present invention.

[0058] Figure 2 This is a schematic diagram of the beam expander provided by the present invention.

[0059] Figure 3 This is a schematic diagram illustrating the working principle of the first / second galvanometer provided by the present invention.

[0060] Figure 4 The flowchart of the tokamak vacuum chamber leakage detection method based on multi-beam laser-induced leakage provided by the present invention is shown.

[0061] Among them, 1. Pulsed laser; 2. Beam expander; 3. Diffractive optical element; 4. Collimating lens; 5. First galvanometer; 6. Second galvanometer; 7. First focusing lens; 8. Dichroic mirror; 9. Observation window; 10. Tokamak vacuum chamber; 11. Focusing lens array; 12. Second focusing lens; 13. Fiber optic probe; 14. Fiber optic cable; 15. Spectrometer; 16. ICCD camera; 17. Digital delay pulse generator; 18. Computer; 19. Diverging lens; 20. Third focusing lens; 21. First reflecting mirror; 22. First drive motor; 23. Second drive motor; 24. Second reflecting mirror; 25. Plasma. Detailed Implementation

[0062] The specific embodiments of the present invention are described below to enable those skilled in the art to understand the present invention. However, it should be understood that the present invention is not limited to the scope of the specific embodiments. For those skilled in the art, various changes are obvious as long as they are within the spirit and scope of the present invention as defined and determined by the appended claims. All inventions utilizing the concept of the present invention are protected.

[0063] Example 1:

[0064] This embodiment provides a tokamak vacuum chamber leak detection device based on multi-beam laser-induced leakage. Through multi-beam parallel excitation and two-dimensional scanning technology, it realizes remote, real-time, and non-contact online detection of tokamak vacuum chamber leaks.

[0065] refer to Figure 1 The tokamak vacuum chamber leak detection device includes a laser generation and shaping unit, a beam scanning and focusing unit, an optical path coupling and separation unit, and a signal collection unit arranged in sequence.

[0066] The laser generation and shaping unit, the beam scanning and focusing unit, and the optical path coupling and separation unit are arranged sequentially along the laser beam emission path;

[0067] The laser generation and shaping unit is used to generate a laser beam and shape it into several parallel laser beams; the beam scanning and focusing unit is used to control the deflection of the parallel laser beams in the horizontal / vertical direction and convert the angle change of the deflected laser beam into the movement of the focal position, forming an S-shaped reciprocating scanning path; the optical path coupling and separation unit is used to introduce the laser beam into the tokamak vacuum chamber 10 for scanning and to receive the reflected spectral signal.

[0068] The signal acquisition unit is used to collect the spectral signals reflected inside the tokamak vacuum chamber 10 and generate a spectral map for analyzing the gas leakage at the scanning point of the tokamak vacuum chamber 10.

[0069] In this embodiment, Figure 1 In the process, the laser generation and shaping unit includes a pulsed laser 1, a beam expander 2, a diffractive optical element 3, and a collimating lens 4;

[0070] The laser beam generated by the pulsed laser 1 passes sequentially through the beam expander 2, the diffractive optical element 3, and the collimating lens 4;

[0071] The beam expander 2 is used to reduce the divergence angle of the laser beam and adjust the diameter of the laser beam to meet the incident requirements of the diffractive optical element 3.

[0072] The diffractive optical element 3 is used to divide the laser beam into several spatially discrete sub-laser beams with uniform energy distribution.

[0073] Collimating lens 4 is used to correct several sub-laser beams into parallel laser beams.

[0074] like Figure 2 As shown, the beam expander 2 includes a diverging lens 19 and a third focusing lens 20 arranged sequentially on the diverging optical path of the laser beam.

[0075] In the laser generation and shaping unit described above, the pulsed laser 1 can generate high-energy laser pulses with a pulse width of nanoseconds and a wavelength of 1064nm. After being split by the diffractive optical element 3, it forms N=5 spatially discrete sub-laser beams with uniform energy distribution. The collimating lens 4 then corrects the N sub-laser beams that diverge at a certain angle after diffraction into N parallel laser beams.

[0076] In the structural design of the laser generation and shaping unit, considering the large size of the Kamak vacuum chamber (e.g., the EAST vacuum chamber has a circumference of tens of meters), the traditional single-point scanning method is too time-consuming. Parallel excitation can significantly improve the leak detection efficiency of the tokamak vacuum chamber 10. In this embodiment, a combination of "diffractive optical element 3 + collimating lens 4" is used. After the high-energy pulsed laser is expanded, it is incident on the diffractive optical element 3 and split into N spatially discrete sub-beams. These sub-beams are then corrected to parallel light by the collimating lens 4. In this way, a single laser pulse can simultaneously form N high-energy-density focal points on the inner wall of the vacuum chamber, ablate N points to generate plasma 25. By analyzing whether characteristic spectral lines of leaking gas appear in the spectra of these plasmas, it is possible to simultaneously determine whether there is a leak at N points, realizing parallel detection in a physical sense.

[0077] In this embodiment, Figure 1 In the process, the beam scanning and focusing unit includes a first galvanometer 5, a second galvanometer 6, and a first focusing lens 7 arranged sequentially on the light output path of the laser generation and shaping unit;

[0078] The first galvanometer 5 and the second galvanometer 6 are used to control the deflection angles of the parallel laser generated by the laser generator and the shaping unit in the horizontal and vertical directions, respectively.

[0079] The first focusing lens 7 is positioned on the reflected light path of the second galvanometer 6 to converge the deflected parallel laser beam and convert the change in the laser beam angle into a change in the focal position.

[0080] Specifically, in Figure 3 In the middle, the first galvanometer 5 includes a first reflector 21 and a first drive motor 22, and the second galvanometer 6 includes a second reflector 24 and a second drive motor 23;

[0081] The first reflector 21 is fixedly mounted on the rotating shaft of the first drive motor 22. The first drive motor 22 drives the first reflector 21 to deflect, thereby controlling the deflection angle of the parallel laser in the horizontal direction.

[0082] The second reflector 24 is fixedly mounted on the shaft of the second drive motor 23. The second drive motor 23 drives the second reflector 24 to deflect, thereby controlling the deflection angle of the parallel laser in the vertical direction.

[0083] In the aforementioned beam scanning and focusing unit, the first driving motor 22 drives the first reflecting mirror 21 to rotate, thereby changing the deflection angle of the N parallel laser beams in the horizontal direction; the second driving motor 23 drives the second reflecting mirror 24 to rotate, thereby changing the deflection angle of the N parallel laser beams in the vertical direction; the first galvanometer 5 and the second galvanometer 6 are arranged sequentially in the optical path to jointly achieve two-dimensional scanning control of the N parallel laser beams; the first focusing lens 7 converges the N parallel laser beams after being deflected by the galvanometer, converting the change in beam angle into a change in focal point position, thereby forming N movable high-energy-density focal points on the inner wall of the tokamak vacuum chamber 10, with a spacing of 5 mm between each focal point.

[0084] In the structural design of the aforementioned beam scanning and focusing unit, considering that the tokamak vacuum chamber 10 is a fixed and immovable large device, it is impossible to move it as a whole for scanning like a moving sample stage. This embodiment employs a scanning system of "dual galvanometers + focusing lens," which is the only feasible technical solution to achieve remote, non-contact, two-dimensional deflection of the beam within the fixed observation window 9 field of view. Specifically, by controlling the deflection angle of the first / second reflecting mirrors in the first / second galvanometers, the beam direction is changed, and then the first lens focuses the angle change into a two-dimensional displacement of the focal point on the target surface. This is a non-contact, beam-actively-addressable scanning method, the best solution for achieving flexible movement of the focal point on the wall surface without contact or changing the vacuum chamber state.

[0085] In this embodiment, Figure 1 In the optical path coupling and separation unit, there are a dichroic mirror 8 and an observation window 9;

[0086] The observation window 9 is located on the side wall of the tokamak vacuum chamber 10, and the dichroic mirror 8 is located between the first focusing lens 7 and the observation window 9 in the optical path coupling and separation unit.

[0087] The optical path of the dichroic mirror 8 includes a transmission optical path and a reflection optical path;

[0088] The transmission optical path transmits the laser beam focused by the optical path coupling and separation unit through the observation window 9 and introduces it into the tokamak vacuum chamber 10.

[0089] The reflected light path collects the spectral signal emitted by the plasma 25 generated by the laser beam ablation of the inner wall surface of the tokamak vacuum chamber 10, which is then recovered through the observation window 9 and introduced into the signal collection unit.

[0090] In the aforementioned optical path coupling and separation unit, a dichroic mirror 8 is placed at a 45° angle in the optical path between the first focusing lens 7 and the observation window 9. The surface of the dichroic mirror 8 is coated with a special optical film, which has high transmittance for lasers with a wavelength of 1064 nm and high reflectivity for the plasma emission spectrum band from 200 nm to 900 nm. The focused laser beam is introduced into the tokamak vacuum chamber 10 through the dichroic mirror 8 and the observation window 9, and is finally focused on the inner wall surface. Plasma 25 is generated by ablation of the wall material by the laser. The spectral signal emitted by the plasma 25 passes through the observation window 9 and is reflected by the dichroic mirror 8 to the reflection optical path. The observation window 9 provides a channel for the laser and signal light to enter and exit the vacuum chamber, providing the necessary conditions for realizing remote non-contact scanning detection.

[0091] In this embodiment, Figure 1 In the optical path coupling and separation unit, the signal collection unit is set on the reflected light path of the dichroic mirror 8, including a focusing lens array 11, an optical fiber probe 13, an optical fiber 14, a spectrometer 15, an ICCD camera 16, a digital delay pulse generator 17, and a computer 18 arranged in sequence.

[0092] The focusing lens array 11 is used to collect the various spectral signals emitted by the optical path coupling and separation unit;

[0093] Fiber optic probe 13 is used to couple each spectral signal to the corresponding fiber optic cable 14;

[0094] The two ends of the optical fiber 14 are connected to the channel interfaces of the optical fiber probe 13 and the spectrometer 15, respectively, and are used to transmit the spectral signals of each channel to the corresponding channel interface of the spectrometer 15.

[0095] The spectrometer 15 is used to synchronously split the input spectral signal into monochromatic spectral signals distributed according to wavelength.

[0096] The ICCD camera 16 is located at the output light interface of the spectrometer 15 and is used to amplify the monochromatic spectral signal and convert it into a spectral electrical signal.

[0097] The digital delay pulse generator 17 is connected to the pulsed laser 1 and the ICCD camera 16 respectively, and is used to control the delay time between the turn-on of the ICCD camera 16 and the pulsed laser 1. It can perform nanosecond-level timing synchronization control of the system, ensuring that the ICCD camera 16 avoids background noise interference and accurately acquires effective characteristic spectral signals.

[0098] Computer 18 is connected to ICCD camera 16 to receive and process spectral signals. By extracting and analyzing the spectral intensity of characteristic elements of the leaking gas, it generates spectra of each channel, thereby determining the gas leakage situation at the scanning point of the tokamak vacuum chamber 10.

[0099] The focusing lens array 11 includes several horizontally arranged second focusing lenses 12. Each second focusing lens 12 spatially corresponds to a spectral signal emitted by plasma 25 generated by laser ablation in a tokamak vacuum chamber 10, forming a one-to-one corresponding signal acquisition optical path. Specifically, in Figure 1 In the process, the focusing lens array 11 is composed of N horizontally arranged second focusing lenses 12. These N second focusing lenses 12 are spatially aligned with the spectral signals emitted by the N plasmas 25 reflected by the dichroic mirror 8, forming a one-to-one corresponding signal acquisition optical path.

[0100] In this embodiment, during the structural design of the signal collection unit, multiple plasma signals 25 are generated by multi-beam excitation. If a single-channel spectrometer 15 is used to collect them sequentially, the efficiency advantage of parallel excitation will be completely lost, and the time synchronization of signal acquisition at each point cannot be guaranteed. The use of a focusing lens array 11 in conjunction with a multi-channel spectrometer 15 is the inevitable choice for achieving independent, synchronous, and real-time acquisition and comparison of spectral signals at N points. The computer 18 synchronously processes the data from these N channels, and by identifying local abnormal peaks or gradient changes in spectral line intensity, the location of the leak point can be quickly and accurately pinpointed.

[0101] Example 2:

[0102] This embodiment is a further limitation based on Embodiment 1. Its purpose is to provide a method for detecting leaks in a tokamak vacuum chamber based on multi-beam laser-induced leakage. It is implemented based on the multi-beam laser-induced tokamak vacuum chamber leak detection device in Embodiment 1. Other parts not mentioned refer to Embodiment 1 or the prior art.

[0103] like Figure 4 As shown, the tokamak vacuum chamber leak detection method based on multi-beam laser-induced leakage includes the following steps:

[0104] S100, start the pulsed laser 1, and generate pulsed lasers that are expanded by the beam expander 2, split by the diffractive optical element 3, and collimated by the collimating lens 4 to form N spatially discrete parallel lasers with uniform energy distribution.

[0105] The parallel laser is deflected by controlling the rotation of the first galvanometer 5 and the second galvanometer 6. The deflected parallel laser is then focused by the first focusing lens 7 and transmitted through the dichroic mirror 8 and the observation window 9 and focused on the lower left corner of the observation area of ​​the tokamak vacuum chamber 10, which is set as the scanning start position.

[0106] S200: The pulsed laser 1 is triggered by the digital delay pulse generator 17 to emit a laser beam. After passing through the dichroic mirror 8 and the observation window 9, the laser beam is introduced into the inner wall surface of the tokamak vacuum chamber 10 to ablate the wall material and generate plasma 25. The spectral signal emitted by the plasma 25 is reversed and passed through the observation window 9. After being emitted by the dichroic mirror 8, it is coupled into the fiber optic probe 13 by the focusing lens array 11 and transmitted to the spectrometer 15 through the fiber optic cable 14.

[0107] While the digital delay pulse generator 17 triggers the pulsed laser 1 to emit a laser beam, the delay timer is started. In response to reaching the predetermined time, the ICCD camera 16 is triggered to open the gate, converting the N-channel spectral signals into spectral electrical signals and transmitting them to the computer 18, thereby recording the spectral electrical signals of the corresponding channels and generating the spectral map of each channel.

[0108] S300. Keep the second galvanometer 6 stationary and adjust the deflection of the first galvanometer 5 so that the focus of the N parallel laser beams on the inner wall of the tokamak vacuum chamber 10 moves horizontally to the right according to the set step level.

[0109] S400, in response to the focus moving horizontally to the right to the target position, repeat S200 and S300 until the focus moves to the rightmost edge of the observation area;

[0110] S500: Keep the first galvanometer 5 stationary, adjust the deflection of the second galvanometer 6 so that the focus of the N parallel laser beams on the inner wall of the tokamak vacuum chamber 10 moves vertically upward at a set interval. In response to the vertical upward movement of the focus to the target position, execute S200.

[0111] S600. Keep the second galvanometer 6 stationary and adjust the first galvanometer 5 to deflect in the opposite direction, so that the focus of the N parallel laser beams on the inner wall of the tokamak vacuum chamber 10 moves horizontally to the left in a set step.

[0112] S700, in response to the focus moving horizontally to the left to the target position, repeat S200 and S600 until the focus moves to the leftmost edge of the observation area;

[0113] S800, repeat S500, S400, S500 and S700 to make the parallel laser scan the observation area of ​​the tokamak vacuum chamber 10 in an S-shaped reciprocating path until the focus moves to the uppermost edge of the observation area of ​​the tokamak vacuum chamber 10, and the entire observation area is scanned.

[0114] S900: By analyzing the spectral data obtained from scanning within the observation area, the gas leakage situation at the scanning point is determined.

[0115] During the aforementioned detection process, the control of beam scanning and acquisition must meet specific geometric and temporal constraints to ensure the spatial resolution and signal integrity of the detection; specifically:

[0116] The relationship between the displacement d of the focal point on the inner wall of the tokamak vacuum chamber 10 and the deflection angle θ of the first / second galvanometer is: d = f * θ; where f represents the focal length of the first focusing lens 7.

[0117] To ensure image quality, the maximum range d of the scanning area is set. max For: d max =2 * f * θ max θ max This indicates the maximum permissible deflection angle of the first galvanometer 5 and the second galvanometer 6, and that the set step size during left / right scanning is greater than Δd. min = f * Δθ min To ensure that adjacent sampling points are distinguishable; where Δθ min This represents the minimum deflection angle increment of the first galvanometer 5 and the second galvanometer 6;

[0118] During cyclic scanning, to ensure no missed detections, the working cycle T of a single scan is... cycle > T galvo + T LIBS， T galvo T represents the time required for the first / second galvanometer to deflect. LIBS This indicates the time from laser beam excitation to the completion of spectral signal acquisition and transmission by the ICCD camera 16.

[0119] In the aforementioned leak detection process, a single laser pulse, after being split, synchronously excites and detects a miniature array consisting of N points. Multiple beams are fixed to form a parallel detection array, which is driven by a galvanometer to perform an "S-shaped" reciprocating scan on a two-dimensional plane, achieving gridded coverage of the entire observation area. A multi-channel spectrometer 15 and an ICCD camera 16 simultaneously acquire spectral data from all N points in the array, resulting in a spatially correlated dataset obtained in a single acquisition. When analyzing the leak, not only is the intensity of individual spectral lines analyzed, but also the spatial distribution gradient, abnormal peaks, or continuous high-value regions of characteristic spectral line intensities among N adjacent points are comprehensively analyzed to determine the leak location and diffusion trend.

[0120] Specific embodiments have been used to illustrate the principles and implementation methods of this invention. The descriptions of the embodiments above are only for the purpose of helping to understand the method and core ideas of this invention. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this invention. Therefore, the content of this specification should not be construed as a limitation of this invention.

[0121] Those skilled in the art will recognize that the embodiments described herein are intended to help the reader understand the principles of the invention, and should be understood that the scope of protection of the invention is not limited to such specific statements and embodiments. Those skilled in the art can make various other specific modifications and combinations based on the technical teachings disclosed in this invention without departing from the spirit of the invention, and these modifications and combinations are still within the scope of protection of this invention.

Claims

1. A tokamak vacuum chamber leak detection device based on multi-beam laser-induced leakage, characterized in that, It includes a laser generation and shaping unit, a beam scanning and focusing unit, an optical path coupling and separation unit, and a signal collection unit arranged sequentially; The laser generation and shaping unit, the beam scanning and focusing unit, and the optical path coupling and separation unit are arranged sequentially along the laser beam emission optical path; The laser generation and shaping unit is used to generate a laser beam and shape it into several parallel laser beams; the beam scanning and focusing unit is used to control the deflection of the parallel laser beams in the horizontal / vertical direction and convert the angle change of the deflected laser beam into the movement of the focal position to form an S-shaped reciprocating scanning path; the optical path coupling and separation unit is used to introduce the laser beam into the tokamak vacuum chamber (10) for scanning and to receive the reflected spectral signal. The signal collection unit is used to collect the spectral signals reflected inside the tokamak vacuum chamber (10) and generate a spectral map for analyzing the gas leakage at the scanning point of the tokamak vacuum chamber (10).

2. The tokamak vacuum chamber leak detection device based on multi-beam laser-induced leakage as described in claim 1, characterized in that, The laser generation and shaping unit includes a pulsed laser (1), a beam expander (2), a diffractive optical element (3), and a collimating lens (4). The laser beam generated by the pulsed laser (1) passes sequentially through the beam expander (2), the diffractive optical element (3), and the collimating lens (4). The beam expander (2) is used to reduce the divergence angle of the laser beam and adjust the diameter of the laser beam to meet the incident requirements of the diffractive optical element (3). The diffractive optical element (3) is used to divide the laser beam into several spatially discrete sub-laser beams with uniform energy distribution. The collimating lens (4) is used to correct several sub-laser beams into parallel laser beams.

3. The tokamak vacuum chamber leak detection device based on multi-beam laser-induced leakage as described in claim 2, characterized in that, The beam expander (2) includes a diverging lens (19) and a third focusing lens (20) arranged sequentially on the diverging optical path of the laser beam.

4. The tokamak vacuum chamber leak detection device based on multi-beam laser-induced leakage as described in claim 1, characterized in that, The beam scanning and focusing unit includes a first galvanometer (5), a second galvanometer (6), and a first focusing lens (7) arranged sequentially on the light output path of the laser generation and shaping unit. The first galvanometer (5) and the second galvanometer (6) are used to control the deflection angles of the parallel laser generated by the laser generator and the shaping unit in the horizontal and vertical directions, respectively. The first focusing lens (7) is disposed on the reflected light path of the second galvanometer (6) to converge the deflected parallel laser beam and convert the change in the laser beam angle into a change in the focal position.

5. The tokamak vacuum chamber leak detection device based on multi-beam laser-induced leakage as described in claim 4, characterized in that, The first galvanometer (5) includes a first reflector (21) and a first drive motor (22), and the second galvanometer (6) includes a second reflector (24) and a second drive motor (23). The first reflector (21) is fixedly mounted on the rotating shaft of the first drive motor (22). The first drive motor (22) drives the first reflector (21) to deflect, thereby controlling the deflection angle of the parallel laser in the horizontal direction. The second reflector (24) is fixedly mounted on the shaft of the second drive motor (23). The second drive motor (23) drives the second reflector (24) to deflect, thereby controlling the deflection angle of the parallel laser in the vertical direction.

6. The tokamak vacuum chamber leak detection device based on multi-beam laser-induced leakage as described in claim 1, characterized in that, The optical path coupling and separation unit includes a dichroic mirror (8) and an observation window (9); The observation window (9) is located on the side wall of the tokamak vacuum chamber (10), and the dichroic mirror (8) is located between the first focusing lens (7) and the observation window (9) in the optical path coupling and separation unit. The optical path of the dichroic mirror (8) includes a transmission optical path and a reflection optical path; The transmission optical path transmits the laser beam focused by the optical path coupling and separation unit through the observation window (9) and then introduces it into the tokamak vacuum chamber (10). The reflected light path collects the spectral signal emitted by the plasma (25) generated by the laser beam ablation of the inner wall surface of the tokamak vacuum chamber (10) through the observation window (9) and introduces it into the signal collection unit.

7. The tokamak vacuum chamber leak detection device based on multi-beam laser-induced leakage as described in claim 1, characterized in that, The signal collection unit is set on the reflected light path of the dichroic mirror (8) in the optical path coupling and separation unit, including a focusing lens array (11), an optical fiber probe (13), an optical fiber (14), a spectrometer (15), an ICCD camera (16), a digital delay pulse generator (17), and a computer (18) arranged in sequence. The focusing lens array (11) is used to collect the various spectral signals emitted by the optical path coupling and separation unit; The fiber optic probe (13) is used to couple each spectral signal to the corresponding fiber optic cable (14). The optical fiber (14) is used to transmit each spectral signal to the corresponding channel interface of the spectrometer (15); The spectrometer (15) is used to synchronously split the input spectral signal into monochromatic spectral signals distributed according to wavelength. The ICCD camera (16) is located at the output light interface of the spectrometer (15) and is used to amplify the monochromatic spectral signal and convert it into a spectral electrical signal. The digital delay pulse generator (17) is connected to the pulse laser (1) and the ICCD camera (16) respectively, and is used to control the delay time between the turn-on of the ICCD camera (16) and the pulse laser (1); The computer (18) is connected to the ICCD camera (16) to receive and process spectral signals, generate spectral maps of each channel, and then determine the gas leakage situation at the scanning point of the tokamak vacuum chamber (10).

8. The tokamak vacuum chamber leak detection device based on multi-beam laser-induced leakage according to claim 7, characterized in that, The focusing lens array (11) includes several horizontally arranged second focusing lenses (12). Each second focusing lens (12) corresponds in space to the spectral signal emitted by the plasma (25) generated by the laser beam ablation in a tokamak vacuum chamber (10), forming a one-to-one corresponding signal acquisition optical path.

9. A method for detecting leaks in a tokamak vacuum chamber based on multi-beam laser-induced leakage, implemented using the multi-beam laser-induced tokamak vacuum chamber leak detection device according to any one of claims 1 to 8, characterized in that, Includes the following steps: S100, start the pulsed laser (1), and generate pulsed lasers that pass through the beam expander (2) for beam expansion, the diffractive optical element (3) for beam splitting, and the collimating lens (4) for collimation, forming N spatially discrete parallel lasers with uniform energy distribution. By controlling the rotation of the first galvanometer (5) and the second galvanometer (6), the parallel laser is deflected. The deflected parallel laser is then focused by the first focusing lens (7) and transmitted through the dichroic mirror (8) and the observation window (9), and focused on the lower left corner of the observation area of ​​the tokamak vacuum chamber (10), which is set as the scanning start position. S200: The pulsed laser (1) is triggered by the digital delay pulse generator (17) to emit a laser beam. After passing through the dichroic mirror (8) and the observation window (9), the laser beam is introduced into the inner wall of the tokamak vacuum chamber (10) to ablate the wall material and generate plasma (25). The spectral signal emitted by the plasma (25) is reversed and passed through the observation window (9). After being emitted by the dichroic mirror (8), it is coupled into the fiber optic probe (13) by the focusing lens array (11) and transmitted to the spectrometer (15) through the fiber optic cable (14). The delay timer is started at the same time the digital delay pulse generator (17) triggers the pulse laser (1) to emit a laser beam. In response to the predetermined time, the ICCD camera (16) is triggered to open the gate, converting the N-channel spectral signals into spectral electrical signals and transmitting them to the computer (18), thereby recording the spectral electrical signals of the corresponding channels and generating the spectral map of each channel. S300. Keep the second galvanometer (6) stationary and adjust the deflection of the first galvanometer (5) so that the focus of the N parallel laser beams on the inner wall of the tokamak vacuum chamber (10) moves horizontally to the right according to the set step level. S400, in response to the focus moving horizontally to the right to the target position, repeat S200 and S300 until the focus moves to the rightmost edge of the observation area; S500: Keep the first galvanometer (5) stationary, adjust the deflection of the second galvanometer (6) so that the focus of the N parallel laser beams on the inner wall of the tokamak vacuum chamber (10) moves vertically upward at a set interval. In response to the vertical upward movement of the focus to the target position, execute S200. S600. Keep the second galvanometer (6) stationary and adjust the first galvanometer (5) to deflect in the opposite direction so that the focus of the N parallel laser beams on the inner wall of the tokamak vacuum chamber moves horizontally to the left in the set step direction. S700, in response to the focus moving horizontally to the left to the target position, repeat S200 and S600 until the focus moves to the leftmost edge of the observation area; S800, repeat S500, S400, S500 and S700 to make the parallel laser scan the observation area of ​​the tokamak vacuum chamber (10) in an S-shaped reciprocating path until the focus moves to the uppermost edge of the observation area of ​​the tokamak vacuum chamber (10) to complete the scanning of the entire observation area; S900: By analyzing the spectral data obtained from scanning within the observation area, the gas leakage situation at the scanning point is determined.

10. The tokamak vacuum chamber leak detection device based on multi-beam laser-induced leakage according to claim 9, characterized in that, The relationship between the displacement d of the focal point on the inner wall of the tokamak vacuum chamber (10) and the deflection angle θ of the first / second galvanometer is: d = f * θ; where f represents the focal length of the first focusing lens (7); The maximum range d of the scanning area max For: d max =2 * f * θ max θ max This indicates the maximum permissible deflection angle of the first galvanometer (5) and the second galvanometer (6), and the set step size is greater than Δd when scanning to the left / right. min = f * Δθ min , Δθ min This represents the minimum deflection angle increment of the first galvanometer (5) and the second galvanometer (6); During cyclic scanning, the working cycle T of a single scan is... cycle > T galvo + T LIBS， T galvo T represents the time required for the first / second galvanometer to deflect. LIBS This represents the time from laser beam excitation to the completion of spectral signal acquisition and transmission by the ICCD camera (16).

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