In-situ molecular beam velocity adaptive measurement system and method in plasma
By mathematically processing multi-location measurement data and analyzing characteristic radiation signals, the problem of molecular beam velocity not being directly measurable in a plasma environment has been solved, enabling accurate and real-time molecular beam velocity measurement. This method is applicable to various fusion devices and reduces implementation costs and equipment maintenance complexity.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SOUTHWESTERN INST OF PHYSICS
- Filing Date
- 2026-02-10
- Publication Date
- 2026-05-29
AI Technical Summary
Existing molecular beam velocity measurement methods cannot be directly measured in a plasma environment, are greatly affected by system response time, and are subject to plasma disturbances and operating condition deviations, thus failing to reflect the true motion state.
By employing mathematical processing of multi-position measurement data, and through a position scanning injection module, a signal monitoring module, and a processing control module, in-situ, accurate, and real-time measurement of molecular beam velocity is achieved. The influence of system response time is automatically deducted by utilizing characteristic radiation signals and data fitting techniques.
It enables accurate measurement of molecular beam velocity in a plasma environment, eliminates systematic errors, improves measurement accuracy, adapts to complex velocity distributions, is applicable to various fusion devices, and reduces implementation costs and equipment maintenance complexity.
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Figure CN122110193A_ABST
Abstract
Description
Technical Field
[0001] This application belongs to the field of molecular beam velocity measurement technology in plasma, specifically relating to an adaptive measurement system and method for in-situ molecular beam velocity in plasma. Background Technology
[0002] In magnetic confinement fusion research, ultrasonic molecular beam injection is a crucial method for achieving plasma fuel feeding, impurity removal, and plasma control. The velocity of the molecular beam during injection is a key physical parameter determining its deposition characteristics and feeding efficiency, directly affecting the penetration depth and deposition location distribution of fuel particles in the plasma. Therefore, accurate measurement of the molecular beam velocity is of paramount importance for optimizing feeding schemes and understanding the physical mechanisms of feeding.
[0003] Currently, molecular beam velocity is primarily measured using the traditional time-of-flight method. This method typically involves arranging multiple detector points along the molecular beam path inside a vacuum chamber and calculating the velocity by measuring the time difference between these points. However, this method has significant limitations when applied to magnetic confinement fusion devices. First, the vacuum chamber presents an extreme environment of high temperature, strong magnetic field, and high particle flux during plasma discharge, making it difficult to install and maintain sophisticated detection equipment. Second, the introduced detectors may disturb the plasma, affecting the stability and repeatability of the discharge. More importantly, the traditional method measures the molecular beam velocity under plasma-free or cold conditions, failing to reflect the actual motion of the molecular beam after interaction with the plasma in a real plasma environment, resulting in significant operational bias.
[0004] In recent years, some studies have attempted to employ non-invasive measurement techniques such as laser-induced fluorescence. While these techniques avoid direct interference with the plasma, they typically require complex laser systems and optical diagnostic equipment, resulting in high costs and complex operation and maintenance. Furthermore, these techniques often rely on specific energy level transitions, requiring different laser systems for different types of molecular beams (such as hydrogen, deuterium, and helium), leading to poor versatility. In terms of measurement principles, most existing techniques assume that the molecular beam maintains a uniform velocity throughout its motion. However, in reality, the molecular beam exhibits a velocity evolution region in the initial injection phase, especially when the valve is close to the plasma, before reaching a stable velocity. Ignoring this velocity evolution process will lead to systematic errors in the measurement results.
[0005] On the other hand, existing velocity measurement methods are generally significantly affected by system response time. The time delay from the opening of the molecular beam valve to the generation of the detection signal involves multiple stages, such as the fixed delay of the valve control power supply, signal transmission delay, and detector response delay. These inherent system delays are difficult to accurately subtract in traditional single-point or two-point measurements and are often ignored or estimated using empirical values, thus reducing measurement accuracy. In addition, device nonlinearity, temperature drift, plasma jitter, random fluid disturbances during valve opening and closing, and friction cannot be pre-calibrated and will introduce errors, still requiring data fitting, ensemble averaging, and other methods to subtract them. Especially in close-range injection, the molecular beam flight time and system response time are on the same order of magnitude; ignoring system delays will cause the velocity measurement value to deviate significantly from the true value. Summary of the Invention
[0006] To address the technical challenges of existing measurement methods, such as the inability to directly measure molecular beam velocity in a plasma environment, significant susceptibility to system response time, and plasma disturbances, this application proposes an adaptive in-situ molecular beam velocity measurement system and method in plasma. Through mathematical processing of multi-location measurement data, it achieves in-situ, accurate, and real-time measurement of molecular beam velocity, providing reliable data support for fueling optimization of fusion devices and plasma physics research.
[0007] This application is achieved through the following technical solution:
[0008] An adaptive measurement system for in-situ molecular beam velocity in plasma includes:
[0009] The position scanning injection module supports configurable scanning with multiple scanning modes for scanning along the plasma radial direction and injecting molecular beams into the plasma;
[0010] The signal monitoring module is set in the direction of molecular beam injection, corresponding to the region of interaction between plasma and molecular beam, and the monitoring field of view covers all points of interaction within the molecular beam scanning range. It uses an optical system to collect characteristic radiation signals and transmits them to the processing and control module.
[0011] In addition, a processing control module is used to synchronously control the start of scanning injection by the position scanning injection module and signal acquisition by the signal monitoring module, and simultaneously acquire the injection control signal of the position scanning injection module and the characteristic radiation signal of the signal monitoring module, record time series data, and perform fitting analysis and derivative calculation based on the time series data to obtain the instantaneous velocity corresponding to each scanning position;
[0012] The characteristic radiation signal is the characteristic spectral line corresponding to the gas atoms of a specific molecular beam. This characteristic spectral line is the characteristic radiation excited by the interaction between the atoms generated by the molecular dissociation and the plasma after the molecular beam is injected into the plasma.
[0013] In some embodiments, the position scanning injection module includes a molecular beam injection valve, a displacement mechanism, a position sensor, and a scanning control unit;
[0014] The molecular beam injection valve is mounted on the displacement mechanism and is used to realize molecular beam injection;
[0015] The displacement mechanism is used to drive the molecular beam injection valve to move radially along the plasma.
[0016] The position sensor is used to monitor the actual position of the molecular beam injection valve in real time and feed it back to the scanning control unit;
[0017] The scanning control unit supports the configuration of scanning parameters and adaptively adjusts the scanning strategy based on preliminary measurement results.
[0018] In some embodiments, the signal monitoring module includes an optical collection system, a spectral screening component, and a photodetector;
[0019] The optical collection system consists of a lens group and an optical fiber. The lens group focuses the radiation light from the region where the molecular beam interacts with the plasma onto the optical fiber inlet, facilitating the transmission of the optical signal to the photodetector.
[0020] The spectral screening component uses a narrowband interference filter with a center wavelength that matches the characteristic spectral lines to filter out interference from other radiation in the plasma.
[0021] The photodetector is used to convert the optical signal filtered by the spectral screening component into an electrical signal and output it to the processing control module.
[0022] In some embodiments, the processing control module includes a timing controller, a data acquisition unit, and a data processing unit;
[0023] The timing controller is used to synchronously control the opening of the molecular beam injection valve, the positioning of the displacement mechanism, and the start of signal acquisition, ensuring the time coordination of the actions of each module;
[0024] The data acquisition unit is used to simultaneously acquire the molecular beam injection valve control signal and the photoelectric detection signal, and record time series data.
[0025] The data processing unit supports automatically selecting the optimal fitting model based on the goodness of fit, and calculating the molecular beam velocity distribution and system response time in real time.
[0026] On the other hand, this application also proposes an adaptive measurement method for in-situ molecular beam velocity in plasma, implemented based on any of the above-mentioned adaptive measurement systems, including:
[0027] The driving molecular beam injection valve scans along the plasma radial direction;
[0028] At each preset scanning position, molecular beam pulse injection is triggered, and the opening time of the corresponding molecular beam injection valve, the start time of the characteristic radiation signal, and the straight-line distance from the valve center to the plasma boundary are recorded simultaneously using the synchronous trigger signal.
[0029] Based on the opening time of the molecular beam injection valve and the start time of the characteristic radiation signal corresponding to each scanning position, the time difference corresponding to that scanning position is obtained, and the time differences and straight-line distances corresponding to all scanning positions are combined to form a distance-time difference data sequence.
[0030] The optimal fitting model is selected based on the molecular beam development state, and the distance-time difference data sequence is fitted to obtain the fitting equation.
[0031] The instantaneous velocity corresponding to each scanning position is obtained by differentiating the fitted equation, thus forming a complete velocity development curve.
[0032] In some embodiments, the driving molecular beam injection valve scans along the plasma radial direction, including:
[0033] Based on the preliminary results of the equal-interval scanning, preliminary characteristics of the molecular beam velocity development were obtained;
[0034] Based on the aforementioned preliminary characteristics, the scanning strategy is dynamically adjusted: the scanning point density is increased in areas with significant velocity changes, i.e., non-interval scanning is adopted; for near-distance injection, far-distance reference scanning points are automatically added.
[0035] In some implementations, the molecular beam pulse injection and data sequence acquisition process includes:
[0036] At each scanning position, molecular beam pulse injection measurements were repeated multiple times to obtain the average opening time of the molecular beam injection valve and the average start time of the characteristic radiation signal at each scanning position, thereby obtaining the average time difference.
[0037] The average time difference is used to form a distance-time difference data sequence with the corresponding straight-line distance.
[0038] In some embodiments, selecting the optimal fitting model based on the molecular beam evolution state includes:
[0039] Linear and nonlinear fitting are performed on the distance-time difference data sequence, and the goodness of fit for linear and nonlinear fitting is calculated.
[0040] When the goodness of linear fit is greater than a set threshold, the molecular beam velocity is determined to be fully developed, and the linear fit result is adopted.
[0041] When the linear fit goodness is less than or equal to the set threshold, and the nonlinear fit goodness is significantly improved, the molecular beam velocity is determined to be in the process of development, and the nonlinear fit result is adopted.
[0042] In some implementations, the method further includes:
[0043] The system response time is determined by the intercept of the fitted curve at a distance of 0, thus achieving accurate deduction of system delay.
[0044] In some implementations, the method further includes:
[0045] During plasma discharge, subsequent scanning parameters are dynamically adjusted based on preliminary measurement results;
[0046] And / or, before performing scanning measurements, the method further includes: calibrating the time response characteristics of the signal monitoring module using a standard light source, recording the delay parameters of the detection device and signal transmission line; adjusting the focal length and gain of the optical system to ensure that the signal-to-noise ratio of the characteristic radiation signal during plasma discharge is greater than or equal to 10:1.
[0047] This application proposes an adaptive measurement system and method for in-situ molecular beam velocity in plasma, which has the following significant advantages:
[0048] (1) Realize true in-situ measurement: directly measure the characteristic signal of the interaction between the molecular beam and the plasma in the plasma environment, without the need to set up additional detection points in the vacuum chamber. The measurement results reflect the true velocity of the molecular beam under actual working conditions, avoiding the working condition deviation of non-in-situ measurement.
[0049] (2) Eliminate system error: By using the method of "position scanning + data fitting", the statistical analysis of multiple measurement points is used to automatically deduct the influence of the fixed response time of the system. Compared with the traditional method of ignoring system delay, the measurement accuracy is improved.
[0050] (3) Monitoring capability: Data acquisition and processing can be completed during the discharge process, supporting multiple scanning measurements during a single plasma discharge, and outputting the molecular beam velocity change curve in real time, providing immediate feedback to the feeding control system and realizing dynamic optimization of feeding parameters.
[0051] (4) The system is simple and reliable: it utilizes the characteristic radiation signal of plasma itself, without the need to introduce complex additional equipment such as lasers and multi-probes. It is compatible with the molecular beam feeding system of existing fusion devices, and only requires the addition of displacement mechanism and optical detection unit. The implementation cost is reduced, and the equipment is easy to maintain and has a low failure rate.
[0052] (5) Adapting to complex velocity distribution: By introducing nonlinear fitting and fine scanning strategies, this application can accurately measure the velocity evolution of molecular beams during the development process, solve the measurement problem of non-constant velocity during close-range injection, expand the applicability of the method, and provide a complete technical solution for the study of molecular beam behavior under different injection conditions.
[0053] (6) High adaptability: By changing the interference filter with different center wavelengths, it can be adapted to the velocity measurement of various molecular beams such as hydrogen, deuterium, and helium. Furthermore, the scanning range and pulse parameters can be adjusted according to the structure and plasma parameters of different fusion devices. It is applicable to various fusion devices such as tokamak and stellarator, and has strong versatility. Attached Figure Description
[0054] The accompanying drawings, which are included to provide a further understanding of the embodiments of this application and form part of this application, do not constitute a limitation on the embodiments of this application. In the drawings:
[0055] Figure 1 This is a block diagram illustrating the principle of the adaptive measurement system proposed in this application.
[0056] Figure 2 This is a flowchart of the adaptive measurement method proposed in the embodiments of this application;
[0057] Figure 3 This is a flowchart illustrating a specific implementation of the adaptive measurement system proposed in this application.
[0058] Figure 4 This is a schematic diagram of the adaptive measurement results proposed in the embodiments of this application; wherein, the dots represent the calculated instantaneous velocities, and the squares represent distance-time difference data points. Detailed Implementation
[0059] In the following, the terms “comprising” or “may include” as used in the various embodiments of this application indicate the presence of a function, operation, or element of the invention and do not limit the addition of one or more functions, operations, or elements. Furthermore, as used in the various embodiments of this application, the terms “comprising,” “having,” and their cognates are intended only to indicate a specific feature, number, step, operation, element, component, or combination of the foregoing and should not be construed as primarily excluding the presence of one or more other features, numbers, steps, operations, elements, components, or combinations of the foregoing, or adding one or more combinations of the foregoing.
[0060] In various embodiments of this application, the expression "or" or "at least one of A and / or B" includes any combination or all combinations of the words listed simultaneously. For example, the expression "A or B" or "at least one of A and / or B" may include A, may include B, or may include both A and B.
[0061] The terms used in the various embodiments of this application (such as "first," "second," etc.) may modify various constituent elements in the various embodiments, but do not limit the corresponding constituent elements. For example, the above terms do not limit the order and / or importance of the elements. The above terms are only used for the purpose of distinguishing one element from other elements. For example, a first user device and a second user device refer to different user devices, although both are user devices. For example, without departing from the scope of the various embodiments of this application, a first element may be referred to as a second element, and similarly, a second element may be referred to as a first element.
[0062] It should be noted that if a description is made of "connecting" one component to another, then the first component can be directly connected to the second component, and a third component can be "connected" between the first and second components. Conversely, when a component is "directly connected" to another component, it can be understood that there is no third component between the first and second components.
[0063] The terminology used in the various embodiments of this application is for the purpose of describing particular embodiments only and is not intended to limit the various embodiments of this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which the various embodiments of this application pertain. The terms (such as those defined in a generally used dictionary) are to be interpreted as having the same meaning as in the context of the relevant technical field and are not to be interpreted as having an idealized or overly formal meaning, unless clearly defined in the various embodiments of this application.
[0064] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the embodiments and accompanying drawings. The illustrative embodiments and descriptions of this application are only for explaining this application and are not intended to limit this application.
[0065] like Figure 1 As shown in the embodiment of this application, an in-situ molecular beam velocity adaptive measurement system in plasma is proposed, including: a position scanning injection module, a signal monitoring module, and a processing and control module.
[0066] The position scanning injection module supports configurable scanning with multiple scanning modes and mainly consists of a molecular beam injection valve, a displacement mechanism, a position sensor, and a scanning control unit. The molecular beam injection valve is mounted on the displacement mechanism and can employ, but is not limited to, an electromagnetically driven pulse valve to achieve molecular beam injection, with a response time of less than or equal to 1 ms and a leakage rate of less than or equal to 1 × 10⁻⁶. -9 Pa・m³ / s ensures the speed and sealing of pulse injection. The displacement mechanism uses, but is not limited to, a servo motor or a ball screw stepper motor to drive the molecular beam injection valve to move radially along the plasma. The displacement range is 0-1000 mm, which can cover the molecular beam injection area of most fusion devices (such as tokamak and stellarator). The positioning accuracy is better than 1 mm, ensuring that the distance measurement error and the position change caused by plasma disturbance have little impact on the velocity calculation. It supports multiple scanning modes: (1) equal interval scanning mode; (2) variable interval fine scanning mode; (3) custom scanning mode. The position sensor uses, but is not limited to, a laser displacement sensor or a grating ruler. The measurement accuracy is 0.1 mm. It monitors the actual position of the valve in real time and feeds it back to the scanning control unit to form a position closed-loop control, avoiding distance measurement deviation caused by mechanical error. The scanning control unit supports flexible setting of scanning parameters, including scanning interval, scanning speed, dwell time, etc. It can adaptively adjust the scanning strategy according to the preliminary measurement results. It can also transmit information in real time according to the valve position of the scanning mechanism and the last closed magnetic surface boundary position in the plasma operation control to ensure the accuracy of distance measurement. It should be noted that, in another embodiment, the position scanning injection module can also scan along a straight line along other target points in other spatial installation schemes.
[0067] The signal monitoring module is positioned along the direction of the molecular beam injection, corresponding to the region where the plasma interacts with the molecular beam. This ensures the monitoring field of view covers all interaction points within the molecular beam scanning range, and is used to acquire characteristic radiation signals. The signal monitoring module mainly includes an optical collection system, a spectral screening component, and a photodetector. The optical collection system consists of a lens group and an optical fiber. The lens group focuses the radiation light from the region where the molecular beam interacts with the plasma onto the fiber optic inlet, facilitating the transmission of the optical signal to the detector and reducing the impact of high-temperature environments on the detector. The spectral screening component is placed in front of the photodetector and can employ, but is not limited to, narrowband interference filters. Its center wavelength matches the characteristic radiation spectrum, filtering out interference from other plasma radiation and improving signal purity. The photodetector uses, but is not limited to, a photomultiplier tube (PMT) or a high-sensitivity CCD with a response time of less than or equal to 10 μs and adjustable gain. It converts the screened optical signal into an electrical signal and outputs it to the processing and control module.
[0068] The processing and control module has functions such as data acquisition, processing, and feedback control. It mainly consists of a timing controller, a data acquisition unit, and a data processing unit. The timing controller can be implemented using, but is not limited to, a field-programmable gate array (FPGA), with a trigger accuracy of ±10 ns. It synchronously controls the opening of the molecular beam injection valve, the positioning of the displacement mechanism, and the initiation of signal acquisition, ensuring the time coordination of the actions of each module. The data acquisition unit can use, but is not limited to, a high-speed data acquisition card with a sampling rate greater than or equal to 1MHz. It simultaneously acquires the molecular beam injection valve control signal and the photoelectric detection signal, recording time-series data. The data processing unit can use, but is not limited to, an industrial computer or embedded processor, integrating multiple algorithms: linear least squares fitting algorithm, nonlinear curve fitting algorithm (polynomial fitting, exponential fitting, etc.), real-time derivative calculation algorithm, and automatic data validity judgment algorithm (such as common non-empty checks, threshold checks, and unsupervised learning anomaly detection), etc.; it supports automatically selecting the optimal fitting model based on the goodness of fit and calculating the molecular beam velocity distribution and system response time in real time. Furthermore, this processing and control module also includes a feedback control unit, which supports automatically adjusting the scanning control parameters according to the signal quality during the measurement process.
[0069] Based on the above adaptive measurement system, such as Figure 2 As shown in the embodiments of this application, an adaptive measurement method for in-situ molecular beam velocity in plasma is also proposed, including the following steps:
[0070] Step 1: Drive the molecular beam injection valve to scan along the plasma radial direction, using multiple scanning modes to adapt to different molecular beam development states;
[0071] Step 2: At each preset scanning position, the timing controller triggers molecular beam pulse injection and simultaneously records the opening time of the corresponding molecular beam injection valve, the start time of the characteristic radiation signal, and the straight-line distance from the valve center to the plasma boundary using the synchronous trigger signal; wherein the valve center is determined by the initial spatial calibration of the system, and the position of the plasma boundary is determined by the outermost closed magnetic surface measurement system of the plasma discharge. The straight-line distance between the two can be calculated based on their position coordinates.
[0072] Step 3: Based on the opening time of the molecular beam injection valve and the start time of the characteristic radiation signal corresponding to each scanning position, obtain the time difference corresponding to that scanning position, and form a distance-time difference data sequence with the straight-line distance for all scanning positions.
[0073] Step 4: Select the optimal fitting model based on the molecular beam development state, fit the distance-time difference data sequence, and obtain the fitting equation;
[0074] Step 5: Differentiate the fitted equation to obtain the instantaneous velocity corresponding to each scanning position, forming a complete velocity development curve.
[0075] Among them, the characteristic radiation signal is the characteristic spectral line corresponding to each type of molecular beam. This spectral line is the characteristic radiation excited by the interaction between atoms and plasma after the molecules dissociate following the injection of a specific molecular beam (such as a hydrogen molecular beam, a deuterium molecular beam, etc.) into the plasma. Its intensity is positively correlated with the injection amount of the molecular beam, and its wavelength is in the visible light band, making it easy to collect and detect through an optical system. For example, for a hydrogen molecular beam, the corresponding characteristic spectral line can be selected as the hydrogen Hα spectral line (wavelength 656.3 nm); for a helium molecular beam, the corresponding characteristic spectral line can be selected as the helium He-I spectral line (wavelength 587.6 nm).
[0076] Furthermore, in step 1 of this application embodiment, the location scanning process further includes:
[0077] Based on the preliminary equally spaced scan results, preliminary characteristics of molecular beam velocity development (i.e., linear fit goodness) are obtained. The scanning strategy is dynamically adjusted based on these preliminary characteristics, increasing the scan point density in regions of significant velocity change. For near-distance injection, far-distance reference scan points are automatically added to improve the accuracy of system error subtraction. Specifically, the scanning modes employed include: conventional equally spaced scanning, suitable for cases where velocity development is full; and fine non-equally spaced scanning, which increases the scan density in velocity development regions, reducing the interval to 1 / 3-1 / 5 of the conventional scan to accurately capture velocity evolution characteristics. At each preset scan position, a molecular beam pulse injection is triggered, with the injection pulse width set to a short, resolvable pulse width, such as 2 ms, to ensure sufficient interaction between the molecular beam and the plasma and to avoid disturbances to the plasma state caused by continuous injection. The valve opening time and the start time of the characteristic radiation signal are simultaneously acquired using a synchronous trigger signal, with a time recording accuracy better than 10 μs.
[0078] Furthermore, in step 1 of this application embodiment, the molecular beam pulse injection and data acquisition process further includes:
[0079] For each scanning position, pulse injection measurements are repeated 3-5 times to obtain the average opening time of the molecular beam injection valve and the average start time of the characteristic radiation signal corresponding to each scanning position, thereby obtaining the average time difference and reducing the influence of random noise. That is, this embodiment of the application uses the average time difference as the time difference data in the subsequent fitted data sequence to reduce random noise interference.
[0080] Further, in step 2 of this application embodiment, the resulting distance-time difference data sequence is represented as: {(L1,Δt1), (L2, Δt2), ..., (L... n , Δt n )}, where Li (i=1,2,⋯,n) represents the straight-line distance corresponding to the i-th scan position, Δt i (i=1,2,⋯,n) represents the time difference corresponding to the i-th scan position, and n is the number of scan points. Preferably, n is a positive integer greater than or equal to 5. It should be noted that the time difference in this data sequence is the average time difference.
[0081] Furthermore, in step 3 of this application embodiment, the optimal fitting model selection mechanism is as follows:
[0082] Linear and nonlinear fitting are performed on the distance-time difference data sequence, and the goodness of fit of linear and nonlinear fitting is calculated. When the goodness of fit of linear fitting is greater than a set threshold (e.g., 0.98), the molecular beam velocity is considered to be fully developed, and the linear fitting result is adopted.
[0083] When the goodness of linear fitting is less than or equal to a set threshold, and the goodness of nonlinear fitting is significantly improved, the molecular beam velocity is determined to be in the process of development, and the nonlinear fitting result is adopted.
[0084] Linear fitting employs a uniform motion model to linearly fit the distance-time difference data sequence; nonlinear fitting uses a nonlinear evolution model (such as a quadratic function, exponential function, etc.) to nonlinearly fit the distance-time difference data sequence. Furthermore, when the linear fitting effect is poor (i.e., the goodness of fit is less than or equal to a set threshold), various nonlinear function forms are used for curve fitting, and the optimal fitting model is determined by comparing the fitting effects.
[0085] Furthermore, step 3 of this application embodiment also includes:
[0086] The system response time is determined by the intercept of the fitted curve (i.e. the curve corresponding to the fitted equation) at a distance of 0. Subsequently, the system delay can be accurately deducted by subtracting the system response time from the flight time, and the average velocity of the particle can be calculated directly by dividing the distance by the flight time after deducting the response time.
[0087] Furthermore, the adaptive measurement method proposed in this application embodiment also includes:
[0088] Real-time optimization mechanism for measurement parameters: During plasma discharge, subsequent scanning parameters are dynamically adjusted based on preliminary measurement results to achieve different scanning modes;
[0089] Furthermore, the adaptive measurement method proposed in this application embodiment further includes the following steps before performing scanning measurement:
[0090] Using a standard light source (such as a hydrogen lamp) to calibrate the time response characteristics of the signal monitoring module and record the delay parameters of the detection device and signal transmission line can provide a basis for a rough and rapid estimation of the average velocity of particle flight in physical experimental research.
[0091] Adjust the focal length and gain of the optical system to ensure that the signal-to-noise ratio of the characteristic radiation signal during plasma discharge is greater than or equal to 10:1, thus avoiding time recognition errors caused by weak signals.
[0092] It should be noted that the descriptions of each embodiment in the above embodiments have different focuses. For parts that are not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.
[0093] To verify the feasibility of the adaptive measurement system and method proposed in this application, it was implemented on a medium-sized tokamak fusion device equipped with an ultrasonic molecular beam injection system as a fuel feeding method. The position scanning injection module uses a piezoelectric / electromagnetic driven pulse valve mounted on a precision linear displacement mechanism. The displacement mechanism has a stroke range of 0-800 mm, a positioning accuracy of 0.5 mm, and supports both equal-interval and variable-interval scanning modes. A grating ruler is used to monitor the valve position in real time, with a measurement accuracy of 0.1 mm. In the signal monitoring module, the optical collection system uses a lens group and optical fiber. The spectral screening component uses a narrow-band filter with a center wavelength of 656.3 nm and a bandwidth of 1 nm. The photodetector uses a photomultiplier tube with a response time of 2 μs and adjustable gain. In the processing and control module, the timing controller is developed based on an FPGA with a synchronization accuracy of ±50 ns; the data acquisition unit uses a 16-bit high-speed acquisition card with a sampling rate of 2 MHz; and the data processing unit uses an industrial computer running self-developed data processing software. Specific implementation steps are as follows: Figure 3 As shown:
[0094] System preparation and calibration:
[0095] Before plasma discharge, the system was first calibrated. The signal monitoring module was calibrated using a hydrogen lamp, and the inherent delay of the system was measured to be 35 μs. The optical system gain was set to ensure that the signal-to-noise ratio of the Hα signal was greater than 25:1 when low-parameter injection was performed. The scanning parameters were initialized: the basic scanning interval was 50 mm, and there were a total of 10 scanning points.
[0096] Preliminary scan measurement:
[0097] Preliminary scanning was performed during the plasma discharge level-top phase (t=1000-2000 ms): an equal-interval scanning method was used, starting the scan from 300 mm away from the vacuum chamber boundary; molecular beam pulse injection (pulse width 2 ms) was triggered at each position; the valve opening time and the start time of the characteristic radiation signal were recorded simultaneously; the measurement was repeated 3 times at 10 ms intervals at each position, and the average time difference was calculated; the preliminary scan results showed that in the close-range region (300-600 mm), the time difference had a significant nonlinear relationship with the distance, with a goodness of fit R²=0.89, indicating that the molecular beam velocity was in the development stage.
[0098] Adaptive fine scanning: Based on the preliminary scan results, the system automatically adjusts to fine scanning mode: the scanning interval is increased to 20 mm in the 300-600 mm range; a 50 mm interval is maintained in the 600-800 mm range; two distant reference points at 900 mm and 1000 mm are added; the fine scanning obtains a total of 21 measurement points, forming a complete velocity development curve, such as... Figure 4 As shown.
[0099] Adaptive speed calculation: Model selection. Based on the fitting results, the initial linear fit goodness of R² = 0.89, which does not meet the accuracy requirements. The exponential function fit goodness of R² = 0.98, significantly improving the fitting effect. The system automatically selects the exponential function as the optimal fitting model. The optimal fitting model is then used to fit the time data series to obtain the fitting equation: The instantaneous velocity at each location was calculated by differentiation: for example, when L=150 mm, v=1300 m / s; when L=500 mm, v=1760 m / s (near fully developed velocity). The system response time obtained from the fitted curve is approximately τ = 0.1 ms, which covers the fixed delay portion of the calibration results, as well as the time delay caused by other non-fixed delay components.
[0100] To further verify the superiority of the measurement in the embodiments of this application, a comparative measurement was performed using the conventional time-of-flight method under the same operating conditions. Considering the measurement at 500 mm, the conventional method measured a velocity of 1300 m / s (which only reflects the underdeveloped region and does not deduct the influence of system response).
[0101] The fully developed velocity measured in this embodiment is 1760 m / s, with a relative error of 35%. This embodiment also additionally obtained velocity development curves, revealing the molecular beam acceleration process.
[0102] The adaptive capability of the adaptive measurement system and method proposed in this application is further verified by changing the injection conditions:
[0103] Operating Condition A: Long-distance injection (valve distance from plasma 900 mm)
[0104] The system automatically selects a linear fitting model (R²=0.99).
[0105] The measured constant velocity was ~1900 m / s;
[0106] Scanning time is reduced by half.
[0107] Operating Condition B: Extremely close-range injection (valve 100 mm from plasma)
[0108] The system automatically encrypts scan points to a 10 mm interval;
[0109] An exponential function was used for fitting (R²=0.98).
[0110] The initial acceleration phase was clearly captured.
[0111] Further verification of the real-time feedback application of the adaptive measurement system and method proposed in the embodiments of this application:
[0112] During a long pulse discharge (lasting 5 s), the system achieved real-time feedback control: the first velocity measurement was completed at t=1 s; the injection parameters were automatically optimized based on the measurement results (such as increasing the gas source temperature); a verification measurement was performed at t=1.2 s, showing that the velocity increased to 2500 m / s; and process optimization within a single discharge was achieved.
[0113] In summary, the adaptive measurement system and method proposed in this application have the following technical advantages:
[0114] (1) Measurement integrity: For the first time, the molecular beam velocity development curve was obtained in a real plasma environment, providing key data for the research on feeding physics;
[0115] (2) Adaptability: The system can automatically adjust the scanning strategy and calculation model according to the measurement data to adapt to different injection conditions and molecular beam development states;
[0116] (3) Engineering practicality: The entire measurement process is completed during plasma discharge, which does not affect the normal operation of the device and provides a feasible technical solution for the optimization of fuel feeding for fusion devices.
[0117] (4) Accuracy and reliability: Through multi-position measurement and analysis and automatic deduction of system error, the measurement accuracy is significantly higher than that of traditional methods, providing reliable data support for plasma feeding control.
[0118] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.
[0119] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.
[0120] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.
[0121] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.
[0122] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of this application. It should be understood that the above description is only a specific embodiment of this application and is not intended to limit the scope of protection of this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of protection of this application.
Claims
1. An adaptive measurement system for in-situ molecular beam velocity in plasma, characterized in that, include: The position scanning injection module supports configurable scanning with multiple scanning modes for scanning along the plasma radial direction and injecting molecular beams into the plasma; The signal monitoring module is set in the direction of molecular beam injection, corresponding to the region of interaction between plasma and molecular beam, and the monitoring field of view covers all points of interaction within the molecular beam scanning range. It uses an optical system to collect characteristic radiation signals and transmits them to the processing and control module. In addition, a processing control module is used to synchronously control the start of scanning injection by the position scanning injection module and signal acquisition by the signal monitoring module, and simultaneously acquire the injection control signal of the position scanning injection module and the characteristic radiation signal of the signal monitoring module, record time series data, and perform fitting analysis and derivative calculation based on the time series data to obtain the instantaneous velocity corresponding to each scanning position; The characteristic radiation signal is the characteristic spectral line corresponding to the gas atoms of a specific molecular beam. This characteristic spectral line is the characteristic radiation excited by the interaction between the atoms generated by the molecular dissociation and the plasma after the molecular beam is injected into the plasma.
2. The adaptive measurement system for in-situ molecular beam velocity in plasma according to claim 1, characterized in that, The position scanning injection module includes a molecular beam injection valve, a displacement mechanism, a position sensor, and a scanning control unit; The molecular beam injection valve is mounted on the displacement mechanism and is used to realize molecular beam injection; The displacement mechanism is used to drive the molecular beam injection valve to move radially along the plasma. The position sensor is used to monitor the actual position of the molecular beam injection valve in real time and feed it back to the scanning control unit; The scanning control unit supports the configuration of scanning parameters and adaptively adjusts the scanning strategy based on preliminary measurement results.
3. The in-situ molecular beam velocity adaptive measurement system in plasma according to claim 2, characterized in that, The signal monitoring module includes an optical collection system, a spectral screening component, and a photodetector; The optical collection system consists of a lens group and an optical fiber. The lens group focuses the radiation light from the region where the molecular beam interacts with the plasma onto the optical fiber inlet, facilitating the transmission of the optical signal to the photodetector. The spectral screening component uses a narrowband interference filter with a center wavelength that matches the characteristic spectral lines to filter out interference from other radiation in the plasma. The photodetector is used to convert the optical signal filtered by the spectral screening component into an electrical signal and output it to the processing control module.
4. The adaptive measurement system for in-situ molecular beam velocity in plasma according to claim 3, characterized in that, The processing control module includes a timing controller, a data acquisition unit, and a data processing unit; The timing controller is used to synchronously control the opening of the molecular beam injection valve, the positioning of the displacement mechanism, and the start of signal acquisition, ensuring the time coordination of the actions of each module; The data acquisition unit is used to simultaneously acquire the molecular beam injection valve control signal and the photoelectric detection signal, and record time series data. The data processing unit supports automatically selecting the optimal fitting model based on the goodness of fit, and calculating the molecular beam velocity distribution and system response time in real time.
5. A method for adaptive measurement of in-situ molecular beam velocity in plasma, characterized in that, Based on the adaptive measurement system according to any one of claims 1-4, it includes: The driving molecular beam injection valve scans along the plasma radial direction; At each preset scanning position, molecular beam pulse injection is triggered, and the opening time of the corresponding molecular beam injection valve, the start time of the characteristic radiation signal, and the straight-line distance from the valve center to the plasma boundary are recorded simultaneously using the synchronous trigger signal. Based on the opening time of the molecular beam injection valve and the start time of the characteristic radiation signal corresponding to each scanning position, the time difference corresponding to that scanning position is obtained, and the time differences and straight-line distances corresponding to all scanning positions are combined to form a distance-time difference data sequence. The optimal fitting model is selected based on the molecular beam development state, and the distance-time difference data sequence is fitted to obtain the fitting equation. The instantaneous velocity corresponding to each scanning position is obtained by differentiating the fitted equation, thus forming a complete velocity development curve.
6. The method for adaptive measurement of in-situ molecular beam velocity in plasma according to claim 5, characterized in that, The driving molecular beam injection valve scans along the plasma radial direction, including: Based on the preliminary results of the equal-interval scanning, preliminary characteristics of the molecular beam velocity development were obtained; Based on the aforementioned preliminary characteristics, the scanning strategy is dynamically adjusted: the scanning point density is increased in areas with significant velocity changes, i.e., non-interval scanning is adopted; for near-distance injection, far-distance reference scanning points are automatically added.
7. The method for adaptive measurement of in-situ molecular beam velocity in plasma according to claim 5, characterized in that, The molecular beam pulse injection and data sequence acquisition process includes: At each scanning position, molecular beam pulse injection measurements were repeated multiple times to obtain the average opening time of the molecular beam injection valve and the average start time of the characteristic radiation signal at each scanning position, thereby obtaining the average time difference. The average time difference is used to form a distance-time difference data sequence with the corresponding straight-line distance.
8. The method for adaptive measurement of in-situ molecular beam velocity in plasma according to claim 5, characterized in that, The selection of the optimal fitting model based on the molecular beam development state includes: Linear and nonlinear fitting are performed on the distance-time difference data sequence, and the goodness of fit for linear and nonlinear fitting is calculated. When the goodness of linear fit is greater than a set threshold, the molecular beam velocity is determined to be fully developed, and the linear fit result is adopted. When the linear fit goodness is less than or equal to the set threshold, and the nonlinear fit goodness is significantly improved, the molecular beam velocity is determined to be in the process of development, and the nonlinear fit result is adopted.
9. The method for adaptive measurement of in-situ molecular beam velocity in plasma according to claim 5, characterized in that, Also includes: The system response time is determined by the intercept of the fitted curve at a distance of 0, thus achieving accurate deduction of system delay.
10. The method for adaptive measurement of in-situ molecular beam velocity in plasma according to claim 5, characterized in that, Also includes: During plasma discharge, subsequent scanning parameters are dynamically adjusted based on preliminary measurement results; And / or, before performing the scanning measurement, the method further includes: calibrating the time response characteristics of the signal monitoring module using a standard light source, and recording the delay parameters of the detection device and the signal transmission line; Adjust the focal length and gain of the optical system to ensure that the signal-to-noise ratio of the characteristic radiation signal during plasma discharge is greater than or equal to 10:1.