SIMULATION METHOD FOR THREE-DIMENSIONAL FULL-SPACE PLASMA RESPONSE IN EAST TOKAMAK

Abstract

The present invention discloses a simulation method for three-dimensional full-space plasma response in EAST tokamak. In numerical simulation of plasma response in an EAST tokamak device, firstly, single frequency waves with different frequencies and amplitudes are selected according to experiment needs, to design waveforms of an external perturbation current field; then selected single frequency current field waveforms are respectively used as driving terms to solve magnetohydrodynamic equations containing an external driving current field to solve the distribution of the single frequency magnetic response signals in a three-dimensional full space; and finally, multiple groups of the single frequency magnetic response signals are superimposed and converted into a time domain space to obtain the three-dimensional full-space distribution of plasma magnetic response signals at any time. The present invention realizes the corresponding full-space distribution of plasma at any time in the process of simulating EAST tokamak discharge experiments, and makes up for the deficiency that the distribution of full-space magnetic signals cannot be obtained by experimental measurement. The present invention has accurate simulation results and strong practicality, and is a stable and efficient numerical simulation method.

Claims

1. A simulation method for three-dimensional full-space plasma response in EAST Tokamak, wherein a disturbance current signal applied in an external coil of an EAST tokamak device is directly used as input information to solve single frequency three-dimensional full-space plasma magnetic response signals, and finally, the magnetic signals in a frequency domain space are converted into a time domain space and superimposed together to ultimately obtain the distribution of the magnetic response signals in a three-dimensional full space at any time; the simulation method comprises the following steps: step 1: according to the cross-section shape of EAST tokamak, meshing a core high-temperature plasma area in an experiment, and storing physical quantity involved in a computational process through mesh nodes obtained by meshing; step 2: designing a waveform of an external perturbation current field δJ according to experimental needs, wherein δJ is formed by superimposing a group of perturbation current with different frequencies and amplitudes, i.e.. δJ=δJ.sub.1+δJ.sub.2+. . . +δJ.sub.n. step 3: measuring initial equilibrium information: intensity of pressure P.sub.0, magnetic field B.sub.0 and current J.sub.0 by using a diagnostic device on an EAST device and storing in the mesh nodes; step 4: storing an external perturbation current signal δJ.sub.1 applied in step 2 into a mesh node in a position corresponding to the external coil; step 5: solving linearized magnetohydrodynamic equations comprising external driving terms and obtaining a magnetic response signal δB.sub.1 the solved equations are:
iωρν.sub.1=−∇P.sub.1+(j.sub.1+δJ.sub.1)×B.sub.0+J.sub.0×δB.sub.1
iωδB.sub.1=∇×(ν.sub.1×B.sub.0)
iωP.sub.1=−ν.sub.1.Math.∇P.sub.0−ΓP.sub.0∇.Math.ν.sub.1
j.sub.1+δJ.sub.1=∇×δB.sub.1 where i is an imaginary number symbol; Γ is an adiabatic coefficient; ω is the frequency of an external perturbation current field δJ.sub.1; ρ is plasma density; P.sub.1 is intensity of pressure of perturbation; j.sub.1 is perturbation current density; ν.sub.1 is perturbation velocity; and δB.sub.1 is the plasma magnetic response signals to be solved; step 6: replacing the external perturbation current signal δJ.sub.1 in step 4 with δJ.sub.2 . . . δJ.sub.n and repeating step 4 and step 5 for several times until all single frequency magnetic response signals δB.sub.1 . . . δB.sub.n are obtained; step 7: converting the magnetic response signals δB.sub.1 . . . δB.sub.n in the frequency domain space into the time domain space, and superimposing the signals together to obtain the three-dimensional full-space plasma magnetic response signal δB.sub.t=δB.sub.1t+δB.sub.2t+. . . +δB.sub.nt at any time.

Description

DESCRIPTION OF DRAWINGS

[0017] FIG. 1 is a cross section schematic diagram of an EAST tokamak device applicable to the present invention.

[0018] FIG. 2 shows an external perturbation current field waveform adopted for simulation of calculation in the present invention.

[0019] FIG. 3 shows numerical results of simulating three-dimensional full-space plasma magnetic response signals on EAST tokamak in the present invention.

[0020] FIG. 4 is a main flow chart for simulation of calculation of three-dimensional full-space plasma response in the present invention.

DETAILED DESCRIPTION

[0021] Specific embodiments of the present invention are further described below in combination with the drawings and the technical solution.

[0022] An EAST tokamak device has a cross-sectional shape as shown in FIG. 1. Two groups of upper and lower external coils are installed on the device to generate an external perturbation current field. A core plasma area is meshed according to an EAST geometry configuration shown in FIG. 1. Before an EAST tokamak discharge experiment, an external perturbation current field waveform shall be designed at first. The present embodiment uses a relatively universal waveform, as shown in FIG. 2. The perturbation current waveform is formed by superimposing single frequency waves with frequencies of 2 Hz, 5 Hz, 10 Hz, 30 Hz, 100 Hz and 150 Hz. Initial equilibrium parameters use general parameters in the EAST discharge experiment, and the equilibrium parameters are stored in the divided meshes. The perturbation current field waveform is applied for numerical simulation. By substituting the above six single frequency current waveforms into magnetohydrodynamic equations containing external driving terms, the plasma magnetic response signals are solved to obtain six single frequency magnetic response signals. Then, the magnetic response signals in the frequency domain space are converted into the time domain space, and superimposed together to obtain the three-dimensional full-space distribution of the plasma magnetic response at any time. As shown in FIG. 3, the figure shows the distribution of the plasma magnetic response signals in the cross section at time t=0.1 s and t=0.4 s in the present embodiment.

[0023] Specific implementation steps are as follows:

[0024] Step 1: according to the cross-section shape of EAST tokamak, meshing a core high-temperature plasma area in an experiment, and storing physical quantity involved in a computational process through nodes obtained by meshing.

[0025] Step 2: designing a waveform of an external perturbation current field δJ according to experimental needs, wherein δJ is generally formed by superimposing a group of perturbation current with different frequencies and amplitudes, i.e., δJ=δJ.sub.1+δJ.sub.2+. . . +δJ.sub.n.

[0026] Step 3: measuring initial equilibrium information (intensity of pressure P.sub.0, magnetic field B.sub.0 and current J.sub.0) by using a diagnostic device on an EAST device and storing in the mesh nodes.

[0027] Step 4: storing an external perturbation current signal δJ.sub.1 applied in step 2 into a mesh node in a position corresponding to the external coil.

[0028] Step 5: solving linearized magnetohydrodynamic equations comprising external driving terms and obtaining a magnetic response signal δB.sub.1.

[0029] The equations solved here are:

iωρν.sub.1=−∇P.sub.1+(j.sub.1+δJ.sub.1)×B.sub.0+J.sub.0×δB.sub.1

iωδB.sub.1=∇×(ν.sub.1×B.sub.0)

iωP.sub.1=−ν.sub.1.Math.∇P.sub.0−ΓP.sub.0∇.Math.ν.sub.1

j.sub.1+δJ.sub.1=∇×δB.sub.1

[0030] where i is an imaginary number symbol; Γ is an adiabatic coefficient; ω is the frequency of an external perturbation current field δJ.sub.1; ρ is plasma density; P.sub.1 is intensity of pressure of perturbation; j.sub.1 is perturbation current density; ν.sub.1 is perturbation velocity; and δB.sub.1 is the plasma magnetic response signals to be solved.

[0031] Step 6: replacing the external perturbation current signal δJ.sub.1 in step 4 with δJ.sub.2 . . . δJ.sub.n and repeating step 4 and step 5 for several times until all single frequency magnetic response signals δB.sub.1 . . . δB.sub.n are obtained.

[0032] Step 7: converting the magnetic response signals δB.sub.1 . . . δB.sub.n in the frequency domain space into the time domain space, and superimposing the signals together to obtain the three-dimensional full-space plasma magnetic response signal δB.sub.t=δB.sub.1t+δB.sub.2t+. . . +δB.sub.nt at any time.

[0033] The above contents are further detailed descriptions of the present invention in combination with preferred technical solutions. The specific implementation of the present invention shall not be considered to be only limited to these descriptions. For those ordinary skilled in the art to which the present invention belongs, several simple deductions and replacements may be made without departing from the conception of the present invention, all of which shall be considered to belong to the protection scope of the present invention.