Kinetic simulation of the ion temperature gradient driven (ITG) turbulence We have studied the anomalous transport mechanism caused by the ITG turbulence by means of our newly-developed kinetic simulation code which satisfies the time-reversal symmetry. Contour maps represent profiles of the electrostatic potential before and after saturation of the instability. One can see that the instability is suppressed by the so-called zonal flow which is generated by the turbulence. A time evolution of the velocity space spectrum of the ion distribution function shown in the color figure indicates that fine-scale fluctuations are continuously produced by the phase mixing.

Relaxation phenomena in spherical tokamak The temporal change in the plasma shape is plotted by the iso-pressure surface and surrounding magnetic field lines. A localized deformation appears along the magnetic field as a result of nonlinear growth of a pressure-driven instability. The deformation causes magnetic reconnection between the torus fields and the external fields, and the heat energy is quickly expelled along the reconnected field lines.

Tilt disruption of a field-reversed configuration plasma The kinetic stabilization effect of the tilt mode is investigated by means of three-dimensional particle simulation. When the stabilization effect is weak, the initial equilibrium profile (left) is disturbed as a result of tilt instability and the generated plasma carries the central hot plasma towards the periphery (right).

MHD simulation of spheromak merging A field-reversed configuration is spontaneously formed by merging of two spheromaks with counter-helicity, where temporal reversal and oscillation of the toroidal magnetic field are also observed. Figure shows snapshots of the magnetic field lines colored by the local pressure.

Theory and Computer Simulation

Simulation Science

Virtual Reality

Fusion Plasmas

Physics of Self-Organization

Evolutional Principles of Self-Organization

NIFS	Theory and Computer Simulation Center