[en] The physical model for explaining the recent experiment in TFTR and the more recent one in JT-60U shows that in the reversed magnetic shear tokamak plasmas the combination of the reversed magnetic shear with the E x B sheared velocity (where electric field E is from ion pressure gradient) and the three ways of coupling between them can make the effective ion thermal diffusivity x_i^eff in the core region reduce significantly

[en] A thirty-six channel optical diagnostic system is constructed to study an internal structure of a field-reversed-configuration plasma. A toroidal and poloidal emissivity profiles of the Bremsstrahlung near the wavelength 550 nm are reconstructed by the Abel inversion and the computed tomography. Field-reversed-configuration plasmas have a hollow profile at the equilibrium phase. A dumbbell structure is obtained at the unstable phase

[en] Simulation results on laser ablation Rayleigh-Taylor instability (LARTI) is presented. It is clarified that linear growth rates of LARTI given by using modified nonlocal electron conduction formula are much lower than that given by using classical Spitzer-Haerm electron conduction formula. The saturation closure and the phase change in the nonlinear stage of LARTI are demonstrated and the collective nonlinearity due to collapse of bubbles is observed

[en] The present day stage of computer simulation has entered into the third phase. The age of computer simulation in plasma physics dawned in the late 1950's when Oscar Buneman and John Dawson developed the sheet particle model. In 1960's and the early part of 1970's, one devoted oneself to refine the particle model and to develop, more practically, fluid magnetic hydrodynamic models so that the feasibility of the computer simulation methodology could be tested. This age can be called 'dawning of computer simulation'. The so-called supercomputer appeared in the late 1970's and the computer simulation entered the second phase where individual nonlinear phenomena have become possible to be attacked. At present when a supercomputer with the ability of higher than 100 GFlops speed and lager than 10GBytes common memory is available, almost any individual nonlinear phenomenon, whatever it may look complex, can be solved. This age may well be called 'the age of nonlinear solver'. However, as far as the authors are satisfied with using a supercomputer for simply solving an individual nonlinear problem, the computer simulation plays only a passive role in science and would never cause a catastrophic transition to it. Then, the modern science of the 20th century based on reductionism would continue in the coming 21st century, thus the 21st century's science would stay boring and tedious. It must be the computer simulation that can refresh this boring state. At NIFS an extensive effort has been made to establish a new paradigm of science in the 21st century by developing a new synthetic methodology of computer simulation, which the authors call the MISSION Project. The authors present this MISSION Project and propose a working hypothesis of the science of complexity in this talk

[en] A self-consistent kinetic particle simulation model for studying plasma behavior in divertor region is developed. The atomic processes, such as excitation and ionization of neutral particles, recombination, and charge exchange as well as Coulomb collisions are introduced by means of Monte Carlo method. This simulation model is applied to study a formation of detached plasma at a divertor region. The preliminary results of one dimensional simulation show the plasma detachment is formed in front of an target/divertor plate by intense injection of neutral particles with temperature of 0.027 eV. The plasma temperature at the detached region sharply drops from the background one of 2.0-3.0 eV to around 1.0 eV. At the detached region heat power of injected electrons is transferred to plasma ions due to Coulomb collisions and finally it is removed by charge exchange process

[en] In solving the ballooning eigenvalue for a low-aspect-ratio stellarator equilibrium it is found that the quasiperiodic behaviour of the equilibrium quantities along a typical magnetic field line can lead to localization of the ballooning eigenfunction (Anderson localization) even in the limit of zero shear. This localization leads to strong field-line dependence of the ballooning eigenvalue, with different branches attaining their maximum growth rates on different field lines. A method is presented of estimating the field-line dependence of various eigenvalue branches by using toroidal and poloidal symmetry operations on the shear-free ballooning equation to generate an approximate set of eigenfunctions. These zero-shear predictions are compared with accurate numerical solutions for the H-1 Heliac and are shown to give a qualitatively correct picture, but finite shear corrections will be needed to give quantitative predictions

[en] By using of a six-channel HCN laser interferometer, the density sawtooth oscillations, which having not been exhibited in the ohmic phase plasma, have been first observed during lower hybrid current drive (LHCD) discharge in the HL-1M device, often accompanied with impurity injected by laser blow-off. Analysis shows that this density sawtooth-like come from the mutual effect of LHCD and impurity

[en] Influences of two kinds of boundary modifications on the dynamics of a reversed field pinch (RFP) have been studied in the STE-2 device. Resonant (inside the reversal surface) helical fields have caused deterioration of the RFP plasmas with higher resistance. The deterioration has been shown to be caused by enhanced coupling of the tearing modes due to overlap of the static and inherent magnetic islands. On the contrary, RFP discharges are slightly improved by the nonresonant helical fields. Stabilizing effect of the external helical current layer on the external kink modes (resistive shell modes) is discussed. Edge current injection with a Madison Symmetric Torus type electron injector has produced unidirectional field-aligned electron beam. The decrease in the local reversal parameter has been observed with no deterioration of the RFP discharges

[en] Three-dimensional magnetohydrodynamic simulations are executed in a full toroidal geometry to clarify the physical mechanisms of the internal reconnection event (IRE), which is observed in the spherical tokamak experiments. The simulation results reproduce several main properties of IRE. The noticeable property in the linear growth of modes are the simultaneous excitation of multiple low n modes, which grow together with the similar growth rates. Spontaneous phase-alignment mechanism among those exited modes is found in the nonlinear stage of the development, which causes bulge-like deformation of torus and subsequent expulsion of heat energy to ambient region

[en] Three-dimensional dynamics of a compact toroid (CT), which is injected into a magnetized target plasma modeling a part of a fusion device is investigated by using magnetohydrodynamic numerical simulations. It is found that the injected CT penetrates into the device region, suffering from a tilting instability. In this process, magnetic reconnection between the CT magnetic field and the device magnetic field takes place, which disrupts the magnetic configuration of the CT. As a result, the high density plasma confined in the CT magnetic field is locally supplied in the device region. Furthermore, the authors examine the penetration depth of the CT high density plasma. And it is revealed that the CT high density plasma is decelerated by the device magnetic field through the compressional heating