National Institutes of Natural Science, National Institute for Fusion Science
Department of Helical Plasma Research, Fundamental Physics Simulation Research Division

New Topics

Published Paper (page 2)

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"Development of Multi-Hierarchy Simulation Model with Non-Uniform Space Grids for Collisionless Driven Reconnection"
S. Usami, R. Horiuchi, H. Ohtani, and M. Den,
Physics of Plasmas Vol.20, 061208 (2013)

Multi-hierarchy simulation result of magnetic reconnection. The left and right panels display magnetic field lines and fluid velocity vectors. The multi-hierarchy model is progressed from the previous model as follows. First, the boundary condition in the downstream is improved from periodic to open, thus outflow can go out across the downstream boundary. Furthermore, non-uniform space grids are adopted in the macro hierarchy so as to calculate larger region.
"Analytic Equilibria of High-Beta Tokamaks with Toroidal and Poloidal Flows and Pressure Anisotropy Associated with Parallel Heat Flux"
A. Ito and N. Nakajima,
Journal of the Physical Society of Japan Vol.82, 064502 (2013)

Profiles of pressures and the magnetic flux in the midplane (left) and the radial component of the diamagnetic current in a poloidal cross section (right) obtained from the analytic solution for tokamak equilibria with flow and pressure anisotropy. 
"Formation and Classification of Amorphous Carbon by Molecular Dynamics Simulation"
A. M. Ito, A. Takayama, S. Saito, and H. Nakamura,
Japanese Journal of Applied Physics Vol.52, 01AL04 (2013)

(Color online) Animation snapshots in the MD simulation for transition from graphite to diamond at a pressure of 15 GPa. The green and red spheres indicate sp2 and sp3 carbon atoms, respectively. The white lines show the side of the simulation box under the periodic boundary condition. 
"Kinetic effects on robustness of electron magnetohydrodynamic structures"
M. Hata, H. Sakagami, and A. Das,
Physics of Plasmas Vol.20, 042303 (2013)

(a) Electron orbit in the case of R=8 at the temperature of 4 keV, where black, blue, and pink lines indicate orbits and color contour represents magnetic field in the z direction.
(b) Schematic for sustained mechanism of electron's orbit, where red shading and yellow arrows express magnetic field in the z direction and radial electric field, and purple and white circles and blue-drifted-circle represent Larmor motion, circular motion via ExB drift, and electron orbit that results from Larmor motion and ExB drift, respectively.
"Macro- and microphysics of magnetic reconnection in a multi-hierarchy open system"
R. Horiuchi, M. Den, T. Tanaka, H. Ohtani, and S. Usami,
Plasma Physics and Controlled Fusion Vol.55, 014008 (2013)

Global MHD simulation of geomagnetosphere reconnection with kinetic resistivity. Spatial profiles of magnetic field lines and pressure are plotted when reconnection sets in (top panels) and when flux rope is formed (bottom panels). The left and right panels stand for the results for an effective resistivity model based on steady collisionless driven reconnection, and those for a constant resistivity model. Color on the lines presents the Bz intensity.
"Visualization of Particle Trajectories in Time-Varying Electromagnetic Fields by CAVE-Type Virtual Reality System"
N. Ohno, H. Ohtani, D. Matsuoka, R. Horiuchi,
Plasma and Fusion Research Vol.7, 1401001 (2012)

CAVE visualization of the time-varying data at (1) T=0, (2) 25 T, and (3) 50ΔT, where ΔT is time interval of storing the simulation data. The color contours on xy and yz planes are ion temperature and a reconnection component of magnetic field, respectively. The blue and white lines are magnetic field and ion trajectories, respectively. The magnetic field lines are drawn by the data at the each time, while the ion trajectories are shown as time-tracing lines from T=0.
"Effects of long rarefied plasma on fast electron generation for FIREX-I targets"
H. Sakagami, A. Sunahara, T. Johzaki, and H. Nagatomo,
Laser and Particle Beams Vol.30, 103-109 (2012)

These figures show time evolutions of averaged core electron temperature over the dense region (ρ>10 g/cm3) without rarefied plasmas(purple) and with rarefied plasmas of different densities, 0.01(green), 0.05(red), 0.1(blue), 0.5(yellow) and 1(gray) critical density for (a) Lrare=150 and (b) 300 μm.
"Simulation of Plasma Flow Injection with Multi-Hierarchy Model Aiming Magnetic Reconnection Studies"
S. Usami, H. Ohtani, R. Horiuchi, and M. Den,
Communications in Computational Physics Vol.11, 1006-1021 (2012)

Bird's eye view of the mass density in the multi-hierarhcy simulation. At the initial state, mass density is uniform. Plasmas smoothly and continuously flow from the MHD to PIC domains through the interface domain.
"Visualization of Three-Dimensional MHD Simulation Data to Study Fine Unstable Motions in a Helical Torus Device"
H. Miura,

Isosurfaces of the pressure in a 3D MHD simulation of a hot magnetized plasma dominated by the ballooning instability are visualized. The flute-like structures of the isosurfaces indicates growth of the ballooning mode. The yellow circle indicates the tangential port of the LHD. 
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