A5006059092- Magnetic confinement fusion research
- Ionosphere and magnetosphere dynamics
- Laser-Plasma Interactions and Diagnostics
- Fusion materials and technologies
- Solar and Space Plasma Dynamics
- Plasma Diagnostics and Applications
- Superconducting Materials and Applications
- Particle accelerators and beam dynamics
- Laser-induced spectroscopy and plasma
- Dust and Plasma Wave Phenomena
- Nuclear reactor physics and engineering
- Computational Fluid Dynamics and Aerodynamics
- Astro and Planetary Science
- Atomic and Molecular Physics
- Inertial Sensor and Navigation
- Physics of Superconductivity and Magnetism
- Fluid Dynamics and Turbulent Flows
- Black Holes and Theoretical Physics
- Gas Dynamics and Kinetic Theory
- Theoretical and Computational Physics
- Electrostatic Discharge in Electronics
- Spacecraft and Cryogenic Technologies
- Electromagnetic Launch and Propulsion Technology
- Advanced Data Storage Technologies
- Simulation Techniques and Applications
National Institute for Fusion Science
2015-2024
Nagoya University
2014-2024
National Institutes of Natural Sciences
2017-2024
The Graduate University for Advanced Studies, SOKENDAI
2012-2021
Fusion Academy
2019
Fusion (United States)
2019
Kyoto University
2018
Max Planck Institute for Plasma Physics
2017
Max Planck Society
2017
Princeton Plasma Physics Laboratory
2014
Extreme ultraviolet (EUV) radiation from laser-produced plasma (LPP) has been thoroughly studied for application in mass production of next-generation semiconductor devices. One critical issue the realization an LPP-EUV light source lithography is conversion efficiency (CE) incident laser power to EUV 13.5-nm wavelength (within 2% bandwidth). Another solving problem damage caused when debris reaches collecting mirror. Here, we present improved balance model, which can be used optimization...
Multiscale gyrokinetic turbulence simulations with the real ion-to-electron mass ratio and β value are realized for first time, where is given by of plasma pressure to magnetic characterizes electromagnetic effects on microinstabilities. Numerical analysis at both electron scale ion used reveal mechanism their cross-scale interactions. Even real-mass separation, ion-scale eliminates electron-scale streamers dominates heat transport, not only ions but also electrons. Suppression eddies,...
Impacts of isotope ion mass on trapped-electron-mode (TEM)-driven turbulence and zonal flows in magnetically confined fusion plasmas are investigated. Gyrokinetic simulations TEM-driven three-dimensional magnetic configuration helical with hydrogen ions real-mass kinetic electrons realized for the first time, linear nonlinear nature collisional effects turbulent transport zonal-flow generation clarified. It is newly found that combined TEM stabilization by associated increase impacts steady...
Linearized model collision operators for multiple ion species plasmas are presented that conserve particles, momentum, and energy satisfy adjointness relations Boltzmann's H-theorem even collisions between different particle with unequal temperatures. The also written in the gyrophase-averaged form can be applied to gyrokinetic equation. Balance equations turbulent entropy density, of electromagnetic fluctuations, transport fluxes heat, collisional dissipation derived from equation including...
Turbulent transport is a key physics process for confining magnetic fusion plasma. Recent theoretical and experimental studies of existing devices revealed the existence cross-scale interactions between small (electron)-scale large (ion)-scale turbulence. Since conventional turbulent modelling lacks interactions, it should be clarified whether are needed to considered in future experiments on burning plasma, whose high electron temperature sustained with fusion-born alpha particle heating....
We have investigated the influence of symmetry properties toroidal magnetic configurations on mechanisms used for determining radial electric field such as momentum balance and ambipolar particle transport. Both neoclassical anomalous transport particles, heat in axisymmetric nonaxisymmetric systems are taken into account. Generally, systems, is determined by ambipolarity condition. For with up–down quasisymmetric stellarator symmetry, it shown using a novel parity transformation that fluxes...
Ion temperature gradient turbulent transport in the large helical device (LHD) is investigated by means of gyrokinetic simulations comparison with experimental density fluctuation measurements ion-scale turbulence. The local Vlasov are carried out incorporating full geometrical effects LHD configuration, and reproduce levels comparable to results. Reasonable agreements also found poloidal wavenumber spectra fluctuations obtained from simulation experiment. Numerical analysis potential on...
Microturbulence in magnetic confined plasmas contributes to energy exchange between particles of different species as well the particle and heat fluxes. Although effect turbulent has not been considered significant previous studies, it is anticipated have a greater impact than collisional low such those future fusion reactors. In this study, gyrokinetic simulations are performed evaluate due ion temperature gradient (ITG) turbulence tokamak configuration. The ITG mainly consists cooling ions...
A novel reduced model for ion temperature gradient (ITG) turbulent transport in helical plasmas is presented. The enables one to predict nonlinear gyrokinetic simulation results from linear analyses. It shown simulations of the ITG turbulence that coefficient can be expressed as a function fluctuation level and averaged zonal flow amplitude. Then, heat diffusivity derived by representing fluctuations amplitude terms growth rate instability response potentials. confirmed good agreement with...
Comprehensive electrostatic gyrokinetic linear stability calculations for ion-scale microinstabilities in an LHD plasma with ion-internal transport barrier (ITB) and carbon “impurity hole” are used to make quasilinear estimates of particle flux explore whether microturbulence can explain the observed outward fluxes that flow “up” impurity density gradient. The ion temperature is not stationary ion-ITB phase simulated discharge, during which core decreases continuously. To fully sample these...
A new gyrokinetic Vlasov simulation code, GKV-X, is developed for investigating the turbulent transport in magnetic confinement devices with non-axisymmetric configurations. Effects of surface shapes three-dimensional equilibrium obtained from VMEC code are accurately incorporated. Linear simulations ion temperature gradient (ITG) instabilities and zonal flows Large Helical Device (LHD) [O. Motojima, N. Oyabu, A. Komori et al., Nucl. Fusion 43, 1674 (2003)] configuration carried out by GKV-X...
Effects of equilibrium-scale radial electric fields (Er0) on the zonal flow response and ion temperature gradient (ITG) instability in magnetically confined plasma with helical configurations are investigated by gyrokinetic simulations. Poloidally global simulations collisionless damping manifest enhancement residual amplitude uniform constant Er0, show agreement function long wavelength limit analytically derived from theory for plasmas multiple-helicity confinement field components. A...
Ion temperature (Ti) gradient modes (ITG modes) and zonal flows for high Ti discharges in the Large Helical Device (LHD) are investigated by linear gyrokinetic Vlasov simulation. In recent LHD experiments, plasmas generated neutral beam injection, spatial profiles of density fluctuations measured phase contrast imaging (PCI) [K. Tanaka et al., Plasma Fusion Res. 5, S2053 (2010)]. The observed most likely propagate direction ion diamagnetic rotation plasma frame, their amplitudes increase...
Abstract The driving and damping mechanism of plasma flow is an important issue because shear has a significant impact on turbulence in plasma, which determines the transport magnetized plasma. Here we report clear evidence due to stochastization magnetic field. Abrupt toroidal associated with transition from nested flux surface stochastic field observed when at rational decreases 0.5 large helical device. This resulting profile flattening are much stronger than expected Rechester–Rosenbluth...
Flux-surface variations of the electrostatic potential are typically neglected in standard neoclassical theory, but 3D devices they can be large enough to affect radial particle flux impurities. The radially local drift-kinetic equation solver SFINCS (stellarator Fokker–Planck iterative conservative solver) (Landreman et al 2014 Phys. Plasmas 21 042503) has been updated account for these variations. In present work we use perform a novel study transport stellarators, where simultaneously...
Impacts of isotope ion mass on ion-scale and electron-scale microinstabilities such as temperature gradient(ITG), trapped electron(TEM), electron gradient(ETG) modes in helical plasmas are investigated by using gyrokinetic Vlasov simulations with hydrogen real-mass kinetic electrons.Comprehensive scans for the equilibrium parameters magnetic configurations clarify transition from ITG to TEM instability, where a significant enhancement is revealed inward-shifted plasma case than that standard...
Abstract Quantitative validation studies of flux-tube gyrokinetic Vlasov simulations on ion and electron heat transport are carried out for the JT-60U tokamak experiment. The temperature gradient (ITG) and/or trapped modes (TEM) driven turbulent zonal flow generations investigated an L-mode plasma in local turbulence limit with a sufficiently small normalized thermal gyroradius weak mean radial electric fields. Nonlinear by GKV code successfully reproduce profiles energy fluxes core region....
A central ion temperature of 7 keV in a neutral beam injection (NBI)-heated plasma and central-electron 20 an electron cyclotron resonance heating were achieved the Large Helical Device (LHD) using upgraded system with newly installed perpendicular-NB injector gyrotrons. The values Ti Te significantly exceeded 5.6 15 keV, obtained previous experiments, respectively. High-Ti was carbon pellet kinetic-energy confinement improved by factor 1.5. Transport analysis high-Ti plasmas showed that...
Abstract Achieving impurity and helium ash control is a crucial issue in the path towards fusion-grade magnetic confinement devices, this particularly case of helical reactors, whose low-collisionality ion-root operation scenarios usually display negative radial electric field which expected to cause inwards pinch. In work we discuss, based on experimental measurements standard predictions neoclassical theory, how plasmas very low ion collisionality, similar those observed hole large device...
Turbulent transport in a high ion temperature discharge of the Large Helical Device (LHD) is investigated by means electromagnetic gyrokinetic simulations, which include kinetic electrons, magnetic perturbations, and full geometrical effects. Including electrons enables us to firstly evaluate particle electron heat fluxes caused turbulence LHD plasmas. It found that energy reproduces experimental result, flux negative. The contribution perturbation small because very low beta. driven...
Plasma turbulence research based on five-dimensional (5D) gyrokinetic simulations is one of the most critical and demanding issues in fusion science. To pioneer new physics regimes both problem sizes timescales, an improvement strong scaling essential. Overlap computations communications using non-blocking MPI communication schemes a promising approach to improving scaling, but it often fails practical applications with conventional libraries. In this work, classical issue resolved by...
Transport and confinement characteristics, microinstabilities for high- isotope plasmas in Large Helical Device are explored by using the gyrokinetic Vlasov simulation GKV with hydrogen ions real-mass kinetic electrons. The experimental data indicate that thermal diffusivity is reduced deuterium-dominated plasmas, where deviation from gyro-Bohm scaling overall tendency strong anomaly of electron heat transport identified. Linear analyses identify growth rates ion temperature gradient trapped...
We assess the magnetic field configuration in modern fusion devices by comparing experiments with same heating power, between a stellarator and heliotron. The key role of turbulence is evident optimized stellarator, while neoclassical processes largely determine transport heliotron device. Gyrokinetic simulations elucidate underlying mechanisms promoting stronger ion scale stellarator. Similar plasma performances these suggests that turbulent should both be next step reactor designs.