| Physicists have aroused strong interest in the nuclear fusion in the research on how the sun and stars are born,how they evolve and whether they will die out.Nuclear fusion reactor power plants will enable humans to take advantage of the stellar's energy while eliminating or substantially reducing the disadvantages of other energy sources,especially fossil fuels.However,fusion energy still has a long way to study before it can be commercialized.The plasma discharge is essentially the gas discharge in strong magnetic field of the tokamak which is a complex electromagnetic system.In essence,it are pulsed devices modelled as a toroidal transformer with one turn secondary plasma ring circuit coupled with a primary poloidal field and a central solenoid coils circuit based on the principle of electrotechnology,so the tokamak plasma discharge is a non-contact discharge.The plasma inductance model,the model of magnetic axis,the normalized radius model of plasma and the self-consistency model of pressure profile in the Tokamak plasma discharges is studied and experimental data analysis by the tokamak transformer theory.The calculation,analysis,model optimization and verification of inductance and magnetic flux evolution in discharge are carried out in EAST tokamak.The the Poynting's and poloidal flux balance equations at different radial locations(the plasma center,boundry and magnetic axis)are derived and applied to calculation of internal and external magnetic flux in EAST tokamak.In order to verify the feasibility of the application of the transformer model in EAST,the voltage balance function is checked by the different cross-section plasma,the different loop voltage values and nearlly same LHCD injection power discharges for LHW current drive both in sustaining plasma discharges and assisting the plasma start-up.Then based on the model,both the inductive current and the non-inductive current in EAST are calculated and analyzed with the long pulse H-mode plasma typical discharge in EAST.The linear and nonlinear components in the vertical magnetic field closely related to magnetic compression are calculated in EAST plasma discharges.It is found that the linear component contributes mainly to the vertical field during the entire discharge process.After magnetic compression,other plasma variables scaling with major(R)or minor(a)radius are stuied and the improved scaling range of both the major-radius compression and the minor-radius compression is figured out in this paper.In addition,the normalized radius of plasma,the relationship between the normalized radius and magnetic compression,and the self-organizing pressure profile are considered,and applied to the plasma analysis of the normalized self-consistent pressure distribution and magnetic compression processes during L-mode and H-mode discharges of EAST.The inductance and magnetic axis model of non-circular plasma cross-section are investigated based on the change of plasma the inductance and magnetic axis caused by magnetic compression,which provides theoretical parameters for the design of magnetic compression process and the real-time control of plasma configuration.The error of the early model was found and corrected in the calculation of magnetic axis.Therefore,the magnetic axis model of non-circular cross-section plasma was proposed and verified by the discharge parameters of EAST.The average error is about 0.015-0.025 m for the different betap cases compared with equilibrium fitting(EFIT)code.What is more,MC processes during L-mode and H-mode discharges are analyzed in the typical plasma discharge.The results of the analysis show that the energy confinement time of plasma agrees well with the scaling law of ITER,which provide a significant foundation for the further experiment of magnetic compression plasma of EAST or CFETR. |
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