A5009240599- Magnetic confinement fusion research
- Ionosphere and magnetosphere dynamics
- Solar and Space Plasma Dynamics
- Plasma Diagnostics and Applications
- Dust and Plasma Wave Phenomena
- Superconducting Materials and Applications
- Fluid Dynamics and Turbulent Flows
- Tensor decomposition and applications
- Laser-Plasma Interactions and Diagnostics
- Quantum chaos and dynamical systems
- Particle accelerators and beam dynamics
- Advanced Combustion Engine Technologies
- Nuclear reactor physics and engineering
- Geophysics and Sensor Technology
- Catalytic Processes in Materials Science
- Nuclear Physics and Applications
- Quantum, superfluid, helium dynamics
- Advanced Neuroimaging Techniques and Applications
- Geomagnetism and Paleomagnetism Studies
- Fusion materials and technologies
- Biodiesel Production and Applications
- Gyrotron and Vacuum Electronics Research
- Aquatic and Environmental Studies
- Cold Fusion and Nuclear Reactions
- Nonlinear Dynamics and Pattern Formation
National Institute of Technology, Kumamoto College
2013-2024
ENN (China)
2021-2022
Rikkyo University
2022
Niigata Sangyo University
2014
Niigata University
2001-2012
Waseda University
2002
Kyoto University
1996
Nagoya University
1990
Mitsubishi Motors (Japan)
1986
Hiroshima University
1973-1976
The relaxation theory of an ideal magnetofluid is developed for a multispecie magnetofluid. Its invariants are the self-helicities, one each specie. Their ``local'' invariance in case follows from helicity transport equation. global forms self-helicities investigated two-fluid (ion and electron), their ruggedness weakly dissipative system defended by cascade selective decay arguments. In general predicts relaxed states with finite pressure sheared flows. familiar single-fluid theory, which...
A comprehensive design study of the D-3He-fueled field-reversed configuration (FRC) reactor Artemis is carried out for purpose proving its attractive characteristics and clarifying critical issues a commercial fusion reactor. The FRC burning plasma stabilized sustained in steady equilibrium by means preferential trapping D-3He fusion-produced energetic protons. novel direct energy converter 15-MeV protons also presented. On bases consistent production simple engineering, compact concept...
QUEST focuses on the steady state operation of spherical tokamak by controlled PWI and electron Bernstein wave current drive. One main purposes is an achievement long duration discharge with MW-class injected power. As result, should be operated in challenging region heat particle handling. To do handling, high temperature all metal wall up to 623 K closed divertors are planned, which realize steady-state under recycling ratio, R = 1. This a dispensable check DEMO, because pumping avoided as...
Abstract As a new spherical tokamak designed to simplify the engineering requirements of possible future fusion power source, EXL-50 experiment features low aspect ratio vacuum vessel (VV), encircling central post assembly containing toroidal field coil conductors without solenoid. Multiple electron cyclotron resonance heating (ECRH) resonances are located within VV improve current drive effectiveness. Copious energetic electrons produced and measured with hard x-ray detectors, carry bulk...
The relaxation theory of a two-species magnetofluid is presented. This generalizes the familiar magnetohydrodynamic (single-fluid) theory. two-fluid invariants are self-helicities, one for each species. Their “local” invariance follows from helicity transport equations, which derived. global forms self-helicities examined in weakly dissipative system. They shown to pass three tests ruggedness (“relative” compared with energy): cascade test; selective decay and stability resistive modes test....
Spatial distributions of neutral radicals CH3 and CH2 in a capacitively coupled rf glow discharge methane were measured by threshold ionization mass spectrometry. A strong asymmetry the density profile was found for radical high-pressure (∼100 mTorr) discharge. In addition, comprehensive measurements electron energy distribution, ionic composition, sticking coefficient made to use as inputs theoretical modeling plasma. The model predictions agree substantially with distributions.
Standard magnetohydrodynamic (MHD) equations are extended to include arbitrary equilibrium flows and multiple fluids an equivalent variational form is developed. This system appropriate for the study of stability in any multifluid flowing plasma, e.g., allowing poloidal toroidal accounting Hall terms. The formalism applied particular case internal tilting instability a field-reversed configuration (FRC). A solution by means Rayleigh–Ritz technique leads dispersion relation, from which growth...
The mission of the National Spherical Torus Experiment (NSTX) is demonstration physics basis required to extrapolate next steps for spherical torus (ST), such as a plasma facing component test facility (NHTX) or an ST based (ST-CTF), and support ITER. Key issues are transport, steady state high β operation. To better understand electron new high- k scattering diagnostic was used extensively investigate gyro-scale fluctuations with varying temperature gradient scale length. Results from n = 3...
A non-relativistic multi-fluid plasma axisymmetric equilibrium model [A. Ishida et al., "Three-fluid and application to spherical torus plasmas sustained by RF electron heating," Plasma Fusion Res. 10, 1403084 (2015)] was developed recently account for the presence of an energetic fluid in addition thermal ion fluids. The formulation a with relativistic electrons is reported this paper. Relativistic effects approximation can appear two ways: due large macroscopic velocity comparable speed...
The variational formulation for a gyroviscous fluid plasma is constructed. This theory offers fluid-based description of perpendicular kinetic effects, generally called finite Larmor radius (FLR) effects. approach avoids the complexity more complete treatment and local singularities that can appear in standard FLR expansion treatment. method applied to internal tilt mode field-reversed configuration (FRC), an instance where clearly breaks down. relative simplicity allows easy computation...
The properties of two-fluid flowing equilibria are explored. This is facilitated by limiting attention to compact toroids in a “stationary-energy” state with uniform density. Flowing found fall into two classes, force-free and non-force-free, referring the absence or presence j×B force. class may have significant flows. Spheromaks this class. non-force-free diamagnetic has Alfvénic poloidal Field reversed configurations (FRCs) Both classes admit arbitrarily large equilibria. occupy certain...
The three magnetohydrodynamic (MHD) waves are followed as they transition under the influence of an increasingly strong Hall current effect to characteristic Hall-MHD model. Also wave normal surfaces and ray (approximating fronts) these waves. changes in nature found be considerable, described both analytically numerically. Most notably, incompressible MHD shear Alfvén becomes a compressible fluid-dynamical with negligible perturbation electromagnetic field, while two become incompressible,...
Experimental evidence is presented for a regulatory principle governing field-reversed configuration (FRC) equilibria. This leads to form of ‘‘profile consistency’’ with which the current profile exhibits remarkable correlation xs (the ratio separatrix radius coil radius). The proposed explanation that these equilibria are regulated by an instability maintains at marginally stable condition.
An improved formalism for a flowing two-fluid equilibrium with constant density is developed. This extends the usual single-fluid model. In this generalization, magnetic field replaced by two quantities, generalized vorticities of each species. Criteria are found when model adequate and more general necessary. The two-dimensional equilibria purely azimuthal ion flow studied analytically numerically. Spherical torus compact toroid that relevant to current experiment. plasma beta as well size...
The gyroviscous fluid theory [L. C. Steinhauer and A. Ishida, Phys. Fluids B 2, 2422 (1990)] is applied to the tilting instability of field-reversed configurations (FRC) using realistic equilibria a more complete basis set than in previous treatment. This leads two important new results. (1) Quantitative agreement found for first time between experiment FRC stability, i.e., stability nearly all FRCs can be explained by theory. (2) (within 30%) also (with modifications account approximately...
The marginal stability of a static plasma with finite-Larmor-radius (FLR) effects depends on combination the FLR effect and ideal magnetohydrodynamic (MHD) potential energy. For tilt mode in field-reversed configuration (FRC) previous computations these two factors led to prediction for S*⩽(3−5)E where S* is macroscale parameter (separatrix radius/ion skin depth) E elongation half length/separatrix radius). This explained observed most experiments. However, recent actual MHD eigenfunctions...
The equilibrium of a field reversed configuration (FRC) with rotating magnetic (RMF) applied externally for maintaining steady state is studied theoretically. momentum balance equations ions and electrons as well the mass have been solved analytically solution FRC RMF, in which rotate at different velocities, has found. It revealed that particle source radial flow neglected previous studies plays an important role
A two-fluid equilibrium model with low-collisionality is developed including a new flow-singularity condition. This description applied to the rapidly rotating, high-performance National Spherical Torus eXperiment (NSTX) [Peng et al., Plasma Phys. Controlled Fusion 47, B263 (2005)]. The replicates primary features of an example equilibrium, such as profiles electron and ion temperatures, density, toroidal flow equilibrium. first full-two-fluid computation two-dimensional rapid near thermal...
New results show that a toroidal plasma can be ideally stable to gross modes without magnetic field. Previous ideal-magnetohydrodynamic (MHD) studies for such systems [commonly called field-reversed configurations (FRC)] have consistently predicted instability the tilting mode (lowest-order kink mode). However, new range of equilibria not previously considered are found, which in ideal-MHD theory. The equilibrium properties promote stability hollow current profile, and racetrack separatrix...
An improved formalism for flowing two-fluid equilibria with nonuniform density is developed in the absence of dissipation. The system axisymmetric can be expressed using second-order partial differential equations stream functions generalized vorticities electron and ion fluids. It found that equilibrium are elliptic when poloidal flow speed less than sound speed. This property differs markedly from single-fluid model. result compared important to determine if well-confined plasmas satisfy...
The local stability of field-reversed configurations (FRC) is analyzed using hydrodynamic theory. equation state includes both compressibility and double-adiabatic effects. For the first time, eigenmodes linearized equations motion have been computed. most unstable modes fast growth rates, comparable to Alfvén transit time across FRC radius; i.e., somewhat faster than frequency (or rate) global modes. In realistic equilibria, concentrate, ballooning-mode style, in high curvature region...
The tilting mode in field-reversed configurations (FRC) is examined using ideal-magnetohydrodynamic stability theory. Tilting, a global mode, the greatest threat for disruption of FRC confinement. Previous studies uniformly found to be unstable ideal theory: objective here ascertain if stable equilibria were overlooked past work. Solving variational problem with Rayleigh-Ritz technique, tilting-stable are sufficiently hollow current profile and sufficient racetrackness separatrix shape....
Reduction des emissions de gaz d'echappement et amelioration du demarrage a froid moteurs diesel grande puissance avec une nouvelle pompe injection variation possible la pression moment d'injection
The nearby-fluids model is an improvement of the basic two-fluid flowing equilibrium system developed elsewhere [L.C. Steinhauer, Phys. Plasmas 6, 2734 (1999)]. a singular perturbation problem in which usually small ion-inertia length (ion skin depth) gives rise to parameter. This has frustrated attempts find practical equilibria. ordering assumes that ion and electron flow surfaces are close (“nearby”) each other but do not coincide exactly. eliminates singularity “softens” stiff...