Method for simulating Tokamak INPA diagnosis passive signal

Abstract

The invention belongs to the field of magnetic confinement controllable nuclear fusion, and discloses a method for simulating Tokamak INPA to diagnose passive signals. The method comprises the following steps: firstly, calculating fast ion steady-state moderated distribution at a corresponding moment by using physical parameters of a neutral beam injection device and a temperature density profile of plasma at the corresponding moment and combining a test particle program, and then simulating distribution of neutral particles near a plasma boundary by using a boundary neutral particle simulation program; and inputting the calculated fast ion steady-state moderated distribution and boundary neutral particle distribution as input files into a fast ion diagnosis simulation program, simulating by using the fast ion diagnosis simulation program to obtain particle flux collected by INPA diagnosis in unit time, and comparing a simulation result with a measured value of INPA. According to the invention, the simulation of INPA diagnosis passive signals is realized, the experimental measurement result can be reproduced in simulation, and efficient numerical analysis is provided for the INPA diagnosis passive signals.

Description

Technical Field

[0001] The invention belongs to the field of magnetic confinement controlled nuclear fusion, relates to numerical simulation of a passive signal of INPA diagnosis of a tokamak device, and specifically is a method for simulating a passive signal of INPA diagnosis of a tokamak. Background Art

[0002] With the continuous progress and development of the times and society, human demand for energy is increasing. For a long time, human life and production energy consumption mainly rely on fossil energy, but fossil energy reserves are limited, and burning fossil energy will also cause environmental pollution and other problems. Nuclear fusion energy has the advantages of abundant resources and no carbon dioxide causing the global greenhouse effect, so it is an ideal new energy source. Among the many controlled nuclear fusion schemes, magnetic confinement is considered to be the most feasible method at present. Therefore, in order to solve this problem, the International Thermonuclear Experimental Reactor (ITER) project was launched internationally. At present, the development and research of nuclear fusion energy has entered the second stage, that is, solving the problem of steady-state combustion. At present, external high-energy neutral beam injection (NBI) is mainly used to achieve heating of fusion reactors. In magnetic confinement fusion devices, when neutral beam injection is used for auxiliary heating, a large number of fast neutral particles will be generated inside the plasma, which are derived from the charge exchange process. These fast neutral particles after charge exchange can well retain the phase space information of fast ions, such as energy, pitch and spatial position, and quickly leave the plasma after being free from magnetic field constraints. The phase space information of these fast neutral particles is of great significance for inferring ion temperature density, fast ion transport and wave-particle interaction. The Imaging Neutral Particle Analyzer (INPA) can capture these fast neutral particles, which helps to invert the phase space distribution of fast ions.

[0003] Currently, the phase space distribution of fast ions is inverted through the active signal of INPA diagnosis. However, due to the existence of neutral particles at the boundary, all active signals are mixed with a certain proportion of passive signals, which will have a certain impact on the accuracy of the inversion. In addition, the passive signal of INPA diagnosis can also reflect the phase space distribution information of some fast ions. Therefore, it is urgent to simulate the passive signal of INPA diagnosis to eliminate the passive signal in the active signal and analyze the generation of the passive signal. Summary of the invention

[0004] In order to solve the problem that the existence of the INPA diagnostic passive signal in the tokamak device affects the inversion of the fast ion phase space distribution, the INPA diagnostic passive signal is simulated by a computer program, and the present invention provides a method for simulating the INPA diagnostic passive signal of the tokamak. The present invention proposes a method for simulating the INPA diagnostic passive signal using the fast ion steady-state slowing-down distribution calculated by the test particle program (PTC) and the boundary neutral particle distribution simulated by the boundary neutral particle program (SOLPS-ITER) as input parameters, combined with the diagnostic particle flow program (FIDASIM), which can reproduce the passive signal of the experimental INPA diagnostic measurement. Since the experimental INPA diagnostic passive signal is relatively complex and affected by many factors, the qualitative and quantitative analysis of the source of the experimental signal in the simulation can more accurately invert the distribution of the fast ion phase space. After obtaining the neutral beam injection parameters and the plasma temperature density profile, the simulation of INPA passive signals using the test particle program (PTC), the boundary neutral particle simulation program (SOLPS-ITER), and the fast ion diagnostic simulation program (FIDASIM) has a small amount of calculation, and the simulation results are in good agreement with the experimental measurement results. This method takes into account both the accuracy of the physical process and the high efficiency of the calculation.

[0005] The technical solution adopted by the present invention is:

[0006] A method for simulating a passive signal of a Tokamak INPA diagnostic, comprising the following steps:

[0007] Step 1: Determine the physical parameters of the simulated INPA passive signal corresponding to the gun and the neutral beam injection at the corresponding time and the plasma temperature density profile information, and use the neutral beam injection model to calculate the deposition simulation of fast ions in the plasma. The neutral beam injection model can use a conventional model or a model based on an existing patent (CN 116127822 A), which describes the actual ion source with a reference point in a narrow particle beam, and approximates the geometric length of the beam center to the distance that the particles travel in the plasma to calculate the ionization process of the neutral beam, and ignores the discreteness introduced by the injection hole on the injection source, and the spatial distribution of the neutral beam particles is obtained in an analytical way, realizing the simulation of the neutral beam injection process in the tokamak plasma.

[0008] Step 2: Use the fast ion trajectory tracking program (PTC) and the Monte Carlo collision model to calculate the steady-state distribution function after the Coulomb collision between the fast ion and the background plasma. The specific collision equation is:

[0009]

[0010] Among them, f α (v,t) is the distribution function of the test particle, α represents the test particle, F i(v,t) is the friction term, D ik (v,t) is the diffusion tensor, v is the velocity vector of the test particle, t is the time, i is the component of the test particle in different directions, k is the component of the particle colliding with the test particle in different directions, v i To test the velocity components of particles in different directions, v k is the velocity component of the particle colliding with the test particle in different directions, ξ i (t) is Gaussian white noise, v ∥ is the velocity parallel to the magnetic field, Δv ∥ is the change of velocity in the direction parallel to the magnetic field, v ⊥ is the velocity in the direction perpendicular to the magnetic field, Δv ⊥1 With Δv ⊥2 is the change of velocity in the direction perpendicular to the magnetic field, v sd is the slowing speed, v 0 is the velocity vector before the collision, v 0 is the velocity scalar before the collision, Δt ec is the time step for calculating the elastic collision operator, N 1 , N 2 , N 3 is a Gaussian random number, are unit vectors with different speed directions.

[0011] Step 3: Use the simulation program for neutral particles at the boundary of tokamak plasma (SOLPS-ITER) to simulate the distribution of neutral particles at the boundary of plasma.

[0012] Step 4: Input the fast ion steady-state slowing-down distribution obtained in step 2 and the boundary neutral particle distribution obtained in step 3 as input files into the fast ion diagnostic simulation program (FIDASIM) to simulate the particle flow collected by INPA. The specific steps are as follows:

[0013] Step 4.1: Obtain the actual position of INPA diagnosis in the tokamak, the number of detection holes, the aperture of the detection holes and other information, convert them into a format that can be read by the fast ion diagnostic simulation program (FIDASIM) and input them into the program.

[0014] Step 4.2: Convert the calculated fast ion steady-state slowing-down distribution into the form of a distribution function and pass it into the fast ion diagnostic simulation program (FIDASIM). Similarly, pass the plasma temperature density profile and boundary neutral particle distribution into the fast ion diagnostic simulation program (FIDASIM) to verify the rationality of the input file.

[0015] Step 4.3: After confirming the rationality of the input file, run the fast ion diagnostic simulation program (FIDASIM). After successful operation, the simulation results of the INPA diagnostic passive signal can be obtained, and then the simulation results are compared with the experimental measurement results.

[0016] The beneficial effects of the present invention are as follows: the present invention utilizes the test particle program (PTC), the boundary neutral particle simulation program (SOLPS-ITER), and the fast ion diagnostic simulation program (FIDASIM) to realize the accurate simulation of the INPA diagnostic passive signal in the tokamak device, and solves the problem that the process of inverting the fast ion phase space distribution through the INPA signal is greatly affected by the passive signal. At the same time, the numerical simulation of the INPA passive signal can reflect the phase space information of the fast ion part, which is an efficient and meaningful numerical simulation method. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 : is the fast ion steady-state slowing-down distribution diagram calculated in the embodiment.

[0018] Figure 2 : is the distribution diagram of boundary neutral particles calculated in the embodiment.

[0019] Figure 3 is an example diagram of a simulated INPA signal in an embodiment.

[0020] Figure 4 This is the passive signal diagram of EAST#142319@5500ms INPA diagnostic measurement.

[0021] Figure 5 It is a comparison chart between the simulation results and the experiment in the embodiment.

[0022] Figure 6 It is the main flow chart of the method of the present invention. DETAILED DESCRIPTION

[0023] The present invention is described in detail below with reference to the accompanying drawings and embodiments.

[0024] This example simulates the passive signal of the EAST device #142319@5500ms. In the EAST device, the INPA probe is installed about 0.35m outside the outermost closed magnetic surface and about 0.18m above the mid-plane. The INPA diagnosis on the EAST device has 12 detection holes, which can cover the signal detection from the weak field side to the strong field side. This example first inputs the temperature density profile of EAST#142319@5500ms and the neutral beam injection parameters into the test particle program (PTC) to calculate the fast ion steady-state slowing distribution, such as Figure 1Then, the neutral particle distribution at the boundary is simulated using the boundary neutral particle simulation program (SOLPS-ITER), as shown in Figure 2 Then the fast ion steady-state slowing-down distribution and the boundary neutral particle distribution are input into the fast ion diagnostic simulation program (FIDASIM) to simulate the passive signal of INPA. The simulation example of the fast ion diagnostic simulation program (FIDASIM) is shown in Figure 3 As shown in the figure, the experimentally measured INPA passive signal is as follows Figure 4 As shown in Figure 2, the comparison between the simulation results and the experimental measurement results is shown in Figure 2. Figure 5 As shown, the dotted line is the simulation result, and the solid line is the experimental measurement value. It can be seen that the simulation result is consistent with the experimental measurement result.

[0025] The basic process of the method for simulating the passive signal of Tokamak INPA diagnosis of the present invention is as follows: Figure 6 As shown, the specific implementation steps are as follows:

[0026] Step 1: Determine the physical parameters of the simulated INPA passive signal corresponding to the cannon and the neutral beam injection at the corresponding time and the plasma temperature density profile information. Take EAST#142319@5500ms as an example, modify the data format and pass it into the test particle program (PTC).

[0027] Step 2: Use the fast ion trajectory tracking program (PTC) and the Monte Carlo collision model to calculate the steady-state distribution function after the Coulomb collision between the fast ions and the background plasma, such as Figure 1 shown.

[0028] Step 3: Use the boundary neutral particle simulation program (SOLPS-ITER) to simulate the distribution of neutral particles at the plasma boundary, such as Figure 2 shown.

[0029] Step 4: Input the fast ion steady-state slowing-down distribution and the boundary neutral particle distribution as input files into the fast ion diagnostic simulation program (FIDASIM). The simulation example of the fast ion diagnostic simulation program (FIDASIM) is as follows: Figure 3 As shown, to simulate the particle flow collected by INPA, the specific steps are as follows:

[0030] Step 4.1: Obtain the actual position of INPA diagnosis in the tokamak, the number of detection holes, the aperture of the detection holes and other information, convert them into a format that can be read by the fast ion diagnostic simulation program (FIDASIM) and input them into the program.

[0031] Step 4.2: Convert the calculated fast ion steady-state slowing-down distribution into the form of a distribution function and pass it into the fast ion diagnostic simulation program (FIDASIM). Similarly, pass the plasma temperature density profile and boundary neutral particle distribution into the fast ion diagnostic simulation program (FIDASIM) to verify the rationality of the input file.

[0032] Step 4.3: After confirming the rationality of the input file, run the fast ion diagnostic simulation program (FIDASIM). After successful operation, the simulation results of the passive signal of INPA diagnosis can be obtained. Then compare the simulation results with the experimental measurement results. The experimental measurement results are as follows: Figure 4 The simulation results are then compared with the experimental measurement results. Figure 5 As shown, the dotted line is the simulation result, and the solid line is the experimental measurement value. It can be seen that the simulation result is consistent with the experimental measurement result.

Claims

1. A method for simulating a passive signal of a Tokamak INPA diagnosis, characterized in that: The following steps are involved: Step 1: Determine the physical parameters of the simulated INPA passive signal corresponding to the gun and the neutral beam injection at the corresponding time and the plasma temperature density profile information, and use the neutral beam injection model to calculate the deposition simulation of fast ions in the plasma; Step 2: Use the fast ion trajectory tracking program and the Monte Carlo collision model to calculate the steady-state distribution function after the Coulomb collision between the fast ion and the background plasma. The specific collision equation is: Among them, f α (v,t) is the distribution function of the test particle, α represents the test particle, F i (v,t) is the friction term, D ik (v,t) is the diffusion tensor, v is the velocity vector of the test particle, t is the time, i is the component of the test particle in different directions, k is the component of the particle colliding with the test particle in different directions, v i To test the velocity components of particles in different directions, v k is the velocity component of the particle colliding with the test particle in different directions, ξ i (t) is Gaussian white noise, v ∥ is the velocity parallel to the magnetic field, Δv ∥ is the change of velocity in the direction parallel to the magnetic field, v ⊥ is the velocity in the direction perpendicular to the magnetic field, Δv ⊥1 With Δv ⊥2 is the change of velocity in the direction perpendicular to the magnetic field, v sd is the slowing speed, v0 is the velocity vector before the collision, v0 is the velocity scalar before the collision, Δt ec is the time step for calculating the elastic collision operator, N1, N2, N3 are Gaussian random numbers, are unit vectors with different speed directions; Step 3: Use a simulation program for neutral particles at the boundary of tokamak plasma to simulate the distribution of neutral particles at the boundary of plasma; Step 4: Input the fast ion steady-state slowing-down distribution obtained in step 2 and the boundary neutral particle distribution obtained in step 3 as input files into the fast ion diagnostic simulation program to simulate the particle flow collected by INPA. The specific steps are as follows: Step 4.1: Obtain the real position of INPA diagnosis in the tokamak, the number of detection holes, the aperture of the detection holes and other information, convert them into a format that can be read by the fast ion diagnosis simulation program and input them into the program; Step 4.2: Convert the calculated fast ion steady-state slowing-down distribution into the form of distribution function and input it into the fast ion diagnostic simulation program. Similarly, input the plasma temperature density profile and boundary neutral particle distribution into the fast ion diagnostic simulation program to verify the rationality of the input file. Step 4.3: After confirming the rationality of the input file, run the fast ion diagnosis simulation program. After successful operation, the simulation results of the INPA diagnosis passive signal can be obtained, and then the simulation results are compared with the experimental measurement results.

2. A method for simulating tokamak INPA diagnosis passive signals according to claim 1, characterized in that: The fast ion orbit tracking program is PTC; the boundary neutral particle simulation program is SOLPS-ITER; and the fast ion diagnostic simulation program is FIDASIM.

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