Progress in simulation study of fusion plasmas. MHD equilibrium and stability

The development of numerical simulations based on magnetohydrodynamics (MHD) methods has greatly advanced the understanding of plasma macroscopic equilibrium and stability as described below, and broadened the prospects for future research. First, the three-dimensional equilibrium calculation including the vacuum magnetic field region has advanced the elucidation of the magnetic field line structure of the divertor region in the finite beta. In addition, this study established a numerical calculation method for plasma flow in line with experimental data, and clarified the qualitative effect on macroscopic stability. On the other hand, by incorporating the kinetic effect of thermal ions in MHD, the stabilizing effect of pressure-driven mode by captured particles was elucidated for the first time. Furthermore, this study introduced large eddy simulation in the simulation including the two-fluid effect, and succeeded in effective analysis including the Hall effect and the finite Larmor effect. On the other hand, from another point of view, analysis based on the following new ideas is also progressing. By applying transfer entropy, analysis of the causality law of plasma flow reduction and magnetic field fluctuation growth in MHD events in experiments has advanced. In addition, as a study of optimization of magnetic field coordination, it was shown that the divertor region can be expanded by adding a new poloidal coil to the heliotron magnetic field configuration. In the numerical calculation of pellet absorption, the effect of the presence or absence of magnetic islands on the increase in plasma density was clarified by introducing the heat conduction effect. Furthermore, by introducing the pseudo-annealing method into the simplified equation, its usefulness was shown in the high beta equilibrium calculation. (A.O.)