A5014566606- Magnetic confinement fusion research
- Superconducting Materials and Applications
- Fusion materials and technologies
- Ionosphere and magnetosphere dynamics
- Particle accelerators and beam dynamics
- Laser-Plasma Interactions and Diagnostics
- Solar and Space Plasma Dynamics
- Plasma Diagnostics and Applications
- Nuclear reactor physics and engineering
- Physics of Superconductivity and Magnetism
- Dust and Plasma Wave Phenomena
- Nuclear Materials and Properties
- Gyrotron and Vacuum Electronics Research
- Superconducting and THz Device Technology
- Atomic and Subatomic Physics Research
- Nuclear Physics and Applications
- Nuclear Engineering Thermal-Hydraulics
- Electrostatic Discharge in Electronics
- Surface Roughness and Optical Measurements
- Laser Design and Applications
- Advanced Measurement and Metrology Techniques
- Acoustic Wave Resonator Technologies
- Oceanographic and Atmospheric Processes
- Magnetic Field Sensors Techniques
- Powder Metallurgy Techniques and Materials
National Institutes for Quantum Science and Technology
2018-2023
National Institute for Fusion Science
2004-2019
Fusion Academy
2019
Fusion (United States)
2019
Japan Atomic Energy Agency
2005-2014
Oak Ridge National Laboratory
2009
General Atomics (United States)
2007
University of California, San Diego
2007
Advanced Science Research Center
2001-2005
Massachusetts Institute of Technology
2004
The pressure at the top of edge transport barrier (or ‘pedestal height’) strongly impacts fusion performance, while large localized modes (ELMs), driven by free energy in pedestal region, can constrain material lifetimes. Accurately predicting height and ELM behavior ITER is an essential element prediction optimization performance. Investigation intermediate wavelength MHD ‘peeling–ballooning’ modes) has led to improved understanding important constraints on mechanism for ELMs. combination...
The design progress in a compact low aspect ratio (low A ) DEMO reactor, ‘SlimCS’, and its issues are reported. study focused mainly on the torus configuration including blanket, divertor, materials maintenance scheme. For continuity with Japanese ITER-TBM, blanket is based water-cooled solid breeder blanket. vertical stability of elongated plasma high beta access, segmented into replaceable permanent blankets sector-wide conducting shell arranged inbetween these blankets. numerical...
Operating ITER in the reference inductive scenario at design values of Ip = 15 MA and QDT 10 requires achievement good H-mode confinement that relies on presence an edge transport barrier whose pedestal pressure height is key to plasma performance. Strong gradients occur such conditions can drive magnetohydrodynamic instabilities resulting localized modes (ELMs), which produce a rapid energy loss from region facing components (PFC). Without appropriate control, heat loads PFCs during ELMs...
The energy loss for grassy edge localized modes (ELMs) has been studied to investigate the applicability of ELM regime ITER. is characterized by high frequency periodic collapses 800–1500 Hz, which ~15 times faster than that type I ELMs. divertor peak heat flux due ELMs less 10% This smaller caused a narrower radial extent collapse temperature pedestal. different between and agrees qualitatively with distribution eigenfunctions as determined from ideal MHD stability analysis. dominant...
Rseduction of heat loading appropriate for the plasma facing components such as divertor is crucial a fusion reactor. Power handling by large radiative power loss has been studied in long pulse ELMy H-mode discharges on JT-60U (τ d = 30–35 s). Case 1 argon (Ar) seeding into standard plasmas, where radiation confined region main caused change ELM characteristics from Type-I to Type-III. 2 combination Ar and nitrogen (Ne) gas plasmas with an internal transport barrier (ITB). For case 1, both...
Several small/no ELM regimes such as EDA, grassy ELM, HRS, QH-mode, type II and V ELMs with good confinement properties have been obtained in Alcator C-Mod, ASDEX-Upgrade, DIII-D, JET, JFT-2M, JT-60U NSTX. All these show considerable reduction of instantaneous heat load onto divertor target plates contrast to conventional I energy losses are evaluated less than 5% the pedestal stored energy. These summarized widely categorized by their conditions terms operational space non-dimensional...
The results of stabilizing neoclassical tearing modes (NTMs) with electron cyclotron current drive (ECCD) in JT-60U are described emphasis on the effectiveness stabilization. range minimum EC wave power needed for complete stabilization an m / n = 2/1 NTM was experimentally identified two regimes using unmodulated ECCD to clarify behaviours different plasma parameters: 0.2 < j BS 0.4 W sat d ∼ 3 and marg 2, 0.35 0.46 1.5 2. Here, poloidal toroidal mode numbers; EC-driven density bootstrap...
Edge localized mode (ELM) measurements in many tokamaks, including ASDEX-Upgrade, DIII-D, JET, JT-60U and MAST, are reviewed, which includes progress experimental observations at the plasma edge region by means of fast-time resolved diagnostics with high precision, such as scanning probe, radial interferometer chord, BES tangentially viewing fast-gated camera midplane. ELM dynamics data show that majority particle energy transport should be dominated ion convection physics associated...
The concept for a compact DEMO reactor named 'SlimCS' is presented. Distinctive features of the are low aspect ratio (A = 2.6) and use reduced-size centre solenoid (CS) which has function plasma shaping rather than poloidal flux supply. CS enables us to introduce thin toroidal field coil system contributes reducing weight perhaps lessening construction cost. Low-A merits vertical stability high elongation (κ) normalized beta (βN), leads power density with reasonable physics requirements....
Abstract This paper reports on the evaluation of diamagnetic energy using loops in JT-60SA, largest operating tokamak world, and revisits physics behind poloidal beta (βp) internal inductance (li). During first operation phase measurements were utilized assessing parameters related to plasma equilibrium, such as stored energy, βp li. The evaluated is above 200 kJ with 1 MJ electron cyclotron heating, we observed li rise from around unity 2 during current ramp- down phase. successfully...
Instabilities with frequency chirping in the range of Alfvén eigenmodes have been found domain 0.1% < ⟨βh⟩ 1% and vb||/vA ∼1 high energy neutral beam injection JT-60U. One instability a inside continuum spectrum appears its increases slowly to toroidicity induced eigenmode (TAE) gap on timescale an equilibrium change ( ≈ 200 ms). Other instabilities appear TAE their frequencies very quickly by 10-20 kHz 1-5 ms. During period when these fast sweeping (fast FS) modes occur, abrupt large...
Recent progress in experimental and theoretical studies of edge localized mode (ELM) physics is reviewed for the reactor relevant plasma regimes, namely high confinement that is, H-modes advanced scenarios.
The relationship between particle and heat transport in an internal barrier (ITB) has been systematically investigated reversed shear (RS) high βp mode plasmas of JT-60U. electron effective diffusivity is well correlated with the ion thermal ITB region. ratio flux to flux, calculated on basis linear stability analysis, shows a similar tendency experiment RS plasma strong ITB. However, anomalous smaller than Helium carbon are not accumulated inside even close neoclassical level, but argon...
The mitigation of the large pulsed heat loads induced by edge-localized modes (ELMs) on divertor plates is one most important issues for a tokamak fusion reactor. However, ELMs have been completely suppressed in quiescent H-mode (QH-mode) plasmas produced DIII-D (see Burrell K H et al 2002 Plasma Phys. Control. Fusion 44 A253). One key conditions producing QH-mode that direction neutral beam injection (NBI) should be opposite to plasma current (i.e. ctr-NBI), which then leads toroidal...
The characteristics of momentum transport and plasma rotation in the toroidal direction are studied, using near-perpendicular neutral beam injection (PERP-NBI), co tangential counter (CTR) NBI JT-60U. Diffusive non-diffusive terms evaluated from transient analysis by source modulation. Fast ion losses due to field ripple, which locally induces edge CTR rotation, used as a novel source. Parameter dependence these coefficients i.e. diffusivity (χϕ) convection velocity (Vconv), relation between...
The toroidal plasma rotation generated by the external momentum input and itself (intrinsic rotation) has been separated through a novel transport analysis in JT-60U tokamak device. rotation, which is not determined coefficients input, observed. It found that this intrinsic locally local pressure gradient increases with increasing gradient. This trend almost same for various plasmas: low high confinement mode, co counterrotating plasmas.
Pedestal and global plasma parameters are compared in conventional ELMy H-modes improved confinement discharges from ASDEX Upgrade (AUG), DIII-D, JET JT-60U with varying net input power. Both electron ion pedestal pressures studied. The top pressure pPED increases moderately power all tokamaks, broad agreement the dependence of IPB98(y, 2) scaling. Higher observed AUG high βpol at q95 ~ 6.5 triangularity. For machines scenarios a robust correlation between total thermal stored energy is...
The characteristics of the spatial width H-mode pedestal were investigated in hydrogen and deuterium plasmas JT-60U. Both database analysis dedicated experiments on mass scan indicated that depends very weakly plasma particle species or . Identical profiles edge ion temperature Ti obtained with while profile for is not fixed but differs by a factor ∼1.4 (which square root ratio). In addition, an experiment βpol was also performed. Higher had higher value accompanied greater spite almost...
Recent JT-60U experimental results towards the establishment of advanced tokamak (AT) operation are reviewed. We focused on further expansion operational regime AT plasmas higher β N with wall stabilization. After installation ferritic steel tiles in 2005, high power heating a large plasma cross-section which stabilization is expected has been possible. In 2007, modification supply NBIs improved flexibility profile long-pulse plasmas. The investigation key physics issues for steady-state...
Since its inception in 2002, the International Tokamak Physics Activity topical group on Integrated Operational Scenarios (IOS) has coordinated experimental and modelling activity development of advanced inductive scenarios for applications ITER tokamak. The physics basis prospects have been significantly during that time, especially with respect to results. principal findings this research are as follows. Inductive capable higher normalized pressure (βN ⩾ 2.4) than baseline scenario = 1.8)...
The driving mechanism of toroidal rotation and the momentum transport are studied on JT-60U in relation to direction antiparallel plasma current, i.e. counter (CTR) direction, with near-perpendicular neutral beam (PERP-NB) injection. Fast ion losses due field ripple induce CTR peripheral region, magnitude PERP-NBs reduces by installing ferritic steel tiles as a consequence reduction losses. It is also found that velocity profiles core region can be explained considering diffusivity...
We have observed a bursting mode in the high-$\ensuremath{\beta}$ plasmas above ideal $\ensuremath{\beta}$ limit without conducting wall. The frequency is chirping down as amplitude increases, and its initial value close to precession of trapped energetic particle from perpendicular neutral beams. structure radially extended with peak around $q=2$ surface. This can finally trigger resistive wall (RWM) despite enough plasma rotation for RWM stabilization. It concluded that driven by...
Dedicated experiments on TF ripple effects the performance of tokamak plasmas have been carried out at JET. The was found to a profound effect plasma rotation. central Mach number, M , defined as ratio rotation velocity and thermal velocity, drop function amplitude (δ) from an average value = 0.40–0.55 for operations standard JET δ 0.08% 0.25–0.40 0.5% 0.1–0.3 1%. should be considered when estimating in ITER. With co-current injection neutral beam (NBI), were rotate direction. However,...
Key parts of the ITER scenarios are determined by capability proposed poloidal field (PF) coil set. They include plasma breakdown at low loop voltage, current rise phase, performance during flat top (FT) phase and a ramp down plasma. The discharge evolution has been verified in dedicated experiments. New data obtained from C-Mod, ASDEX Upgrade, DIII-D, JT-60U JET. Results show that for E axis < 0.23–0.33 V m −1 is possible unassisted (ohmic) large devices like JET attainable with using...