With the aim of contributing to comprehension of plasma confinement in toroidal magnetic field, we are promoting theoretical research on fusion plasmas, and pioneering theories of inhomogeneous and nonequibrium plasmas in multidimensions. We are also offering theoretical interpretations for experimental observations of the LHD and other fusion plasmas as Well as proposing improvement schemes.
Application of Theoretical Models
Theories of complex and complicated phenomena in confined plasmas have stages in which reliable models are applied, and stages in which construction of a model is itself at issue. Examples of the former stage include linear stability analysis of the magnetohydrodynamics and calculation of high-energy ion orbits in the LHD. Design of the LHD was based on optimization of these analysis. According to advances in experiments, it is also important to verify the validity and generality of such principles of optimization. At the same time, this research offers a method of fully understanding the structure of complex plasmas, which cannot be obtained from experimental data only.
|Calculations of the orbits of high-energy particles in the LHD
(vacuum vessel and antenna also shown）
|Spatial distribution of ion temperature-gradient
mode in a toroidal-helical plasma
|High-energy ion distribution at time or neutral beam injection|
Construction of Theoretical Models
We are attacking research in which formulation of models is at issue from many stand points, including a proposal of reduced equations for turbulence transport in plasmas, and nonlinear theories of subcritical turbulence of the current diffusive mode. Nonlinear turbulence transport results in creation of a variety of structures in plasmas. Among them, the radial electric field is understood to be important in helical plasmas. This kind of research provides the first step to ward extending the statistical mechanics of general turbulent states, and further development is expected as physics of far-nonequibrium states.
|Turbulent transport coefficient as function of pressure gradient(G0).
Strong turbulent transport occurs even in the linearly stable region(G0<Gc).