A5008632115- Magnetic confinement fusion research
- Ionosphere and magnetosphere dynamics
- Superconducting Materials and Applications
- Fusion materials and technologies
- Plasma Diagnostics and Applications
- Solar and Space Plasma Dynamics
- Particle accelerators and beam dynamics
- Nuclear reactor physics and engineering
- Laser-induced spectroscopy and plasma
- Laser-Plasma Interactions and Diagnostics
- Magnetic Field Sensors Techniques
- Nuclear Physics and Applications
- Dust and Plasma Wave Phenomena
- Geomagnetism and Paleomagnetism Studies
- Atomic and Molecular Physics
- Vacuum and Plasma Arcs
- Semiconductor Quantum Structures and Devices
- Quantum, superfluid, helium dynamics
- Laser Design and Applications
- Advancements in Semiconductor Devices and Circuit Design
- Thin-Film Transistor Technologies
- Electrohydrodynamics and Fluid Dynamics
- Spectroscopy and Laser Applications
- Quantum and electron transport phenomena
- Solid State Laser Technologies
Nagoya University
2011-2022
Universitat Politècnica de Catalunya
2006
Hyogo University
1997
National Institute for Fusion Science
1991-1995
National Institutes of Natural Sciences
1993-1995
Osaka Institute of Technology
1995
Mitsubishi Electric (United States)
1995
Czech Academy of Sciences, Institute of Plasma Physics
1980-1987
The transition of a radial electric field from negative to positive value is observed in the compact helical system when electron loss sufficiently enhanced by superposition off-axis second harmonic cyclotron heating on neutral beam heated plasmas. Existence threshold for particle flux required cause experimentally certified. compared with theoretical prediction.
High beta plasmas with a volume averaged equilibrium value of 2.1% were produced in CHS using tangential neutral beam injection. This was achieved the confinement improvement (reheat mode) observed after turning off strong gas puffing. Wall conditioning titanium gettering used to make high density operation (ne ⩽ 8 × 1019 m-3) possible for low magnetic fields (Bt = 0.6 T). The discharges start hill configuration (in vacuum) and finally achieve Mercier stable owing self-stabilization effect...
The MHD equilibrium properties of neutral beam heated plasmas have been experimentally investigated in the Compact Helical System (CHS)-a low aspect ratio (Ap ~ 5) heliotron/torsatron. This configuration is characterized by a strong breaking helical symmetry. radial profiles measured various diagnostics shown significant Shafranov shift due to plasma pressure. deviation magnetic axis from vacuum position has become as large 50% minor radius. When three-dimensional code VMEC used reconstruct...
A complete single chip radio IC technology is discussed. It was possible to include intermediate frequency (IF) filters in a by reducing the IF. Degradation of image interference characteristics can be avoided canceling circuits with inphase/quadrature mixers and phase shift network. Two ICs were developed for FM-stereo/AM AM-only using this technology. The work at supply voltage 0.95-V.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
Characteristics of the H-mode transition observed in CHS are described. The is achieved with modification rotational transform profile by inducing a small ohmic heating current. often initiated sawtooth crash caused coherent mode poloidal number m=2 and toroidal one n=1.
The toroidally asymmetric flux enhancement (“dynamo effect”) and the axisymmetrization of enhanced fluxes that follows in setting up phase Reversed Field Pinch are investigated on STP-3(M) device. A rapid increase toroidal generated by dynamo effect is first observed near poloidal current feeders. Then, this inhomogeneity propagates towards plasma current. attained just after maximum MHD activities decrease significantly quiescent period obtained.
The radial profile of the poloidal field inside plasma column was measured in TOKASTAR-2 using a multichannel magnetic probe with 10 sensors direction. position current center and its movement were observed. oscillation suppressed helical field.
The tokamak plasma position and shape were estimated for the first time in TOKASTAR-2 based on external magnetic measurement using filament current approximation method. Data of a probe array flux loops was used. Effects helical field radial investigated. oscillation outer displacement under weak vertical suppressed by field.
The high-speed camera was used to evaluate the position of plasma in TOKASTAR-2. A plane mirror installed vacuum vessel expand field view and get image whole region between inner outer walls. images were taken at 86400 FPS with 256 × 128 pixels (20 µm/pixel) per frame tokamak discharge without external helical field. Under condition weak vertical field, control improved by outward displacement suppressed located stably contact legs TF coils.
The compact spherical tokamak-stellarator hybrid system, TOKASTAR, has been proposed, and particle orbit analysis in this pure-stellarator configuration carried out. In the original produced by an outboard-side helical coil central straight post, average rotational transform is rather small, several improved configurations were evaluated. Improved confinement of charged particles was achieved replacing post with inboard-side system. To demonstrate concept experimentally, Compact-TOKASTAR...
In order to study a new method of generating energetic ion, linear plasma device NUMBER was designed and constructed. The consists production region test connected axially. radial profile the electron density temperature were measured using Langmuir probe. radius is consistent with field line trace calculation. time evolution ion saturation current Iis measured. A high phase accompanied by rapid increase decrease observed. From scan magnetic in region, it found that may be caused unexpected...
To improve capability of tokamak plasma equilibrium control in TOKASTAR-2, a pair pulsed vertical field coils (PVF coils) was installed 2012. Optimization PVF coil current waveform made with re-calculation using TOSCA code varying the conditions discharge. Then, simulation electric circuit system LTspice done to find optimum capacitance and charging voltage capacitor for consistent optimal waveform. Eventually parameters be used as base experiment were obtained.
Reference 1-GWe DT reactors (tokamak TR-1, spherical tokamak ST-1 and helical HR-1 reactors) are designed using physics, engineering cost (PEC) code, their plasma behaviours with internal transport barrier operations analysed toroidal analysis linkage (TOTAL) which clarifies the requirement of deep penetration pellet fuelling to realize steady-state advanced burning operation. In addition, economical environmental assessments were performed extended PEC shows advantage high beta in...
Cost evaluation analysis of the tokamak-type demonstration reactor DEMO using PEC (physics-engineering-cost) system code is underway to establish a cost model for design. As reference case, with SSTR (steady state tokamak reactor) was designed code. The calculated total capital in same order that proposed previously studies SSTR. Design parameter scanning and multi regression illustrated effect parameters on cost. predicted be inside range several thousands M$s this study.
The radial electric field is driven to positive value by off-axis second harmonic electron cyclotron heating (ECH) in the Compact Helical System [Plasma Physics and Controlled Nuclear Fusion Research 1988, Nice (International Atomic Energy Agency, Vienna, 1989), Vol. II, p. 411]. observed associated with outward particle flux enhanced ECH. triggered production of electrons accelerated perpendicularly magnetic ECH results change field.
Improvement of the vertical stability tokamak plasma with only local coils above and below was observed for first time. The in triangular shape, named upper lower (ULT) coils, were installed TOKASTAR-2, a tokamak-stellarator hybrid device at Nagoya University. ULT generate effective radial magnetic field BReff, which is expected to stabilize position. region position where displacement events (VDEs) did not occur extended by applying field. Stabilization related ratio vertical-direction...
In the future fusion reactor, plasma density peaking is important for increase in power gain and achievement of confinement improvement mode. Density control internal transport barrier (ITB) formation due to pellet injection have been simulated tokamak helical reactors using toroidal linkage code TOTAL. First, simulation carried out, including neutral gas shielding model mass relocation TOTAL code, effectiveness high-field side (HFS) clarified. Second, ITB with out based on E × B shear...
In fusion reactors, high-Z materials will be used to balance the need accommodate high heat load on divertor plates against consistency between burning plasmas and plasma facing component (PFC) materials. However, impurities from these PFCs cause large radiation loss even if amount of is quite small. High-Z impurity transport analysis including sawtooth effects carried out using toroidal linkage (TOTAL) code. The Bohm-type anomalous model for core inward flow ions are in addition...
TOKASTAR, a hybrid magnetic configuration between tokamak and stellarator, has been proposed for the study of confinement optimization. The construction small device named TOKASTAR-2 was started in April 2008, completed March 2009. As preliminary experiment, spatial distribution electron temperature (Te) density (ne) are measured simple toroidal field configuration. Initial ECH plasmas with Te ∼ 10 eV, ne 1016 m−3 confirmed. In experiment ohmic heating plasma production, current (Ip) 25 A is...
TOKASTAR-2 is a small tokamak-helical hybrid device which can generate tokamak and helical configurations independently. In discharge experiment, the conductive shell was installed to increase plasma current by controlling displacement of ohmically heated (OH) plasma. The suppression vertical demonstrated, but OH still located slightly above mid plane. To compensate this displacement, balance between up down field coil currents should be adjusted. addition, construction additional coils...
The bootstrap current and electron thermal conductivity have been investigated in ECRH plasmas on the CHS heliotron/torsatron. neoclassical transport coefficients externally controlled over a wide range by changing ellipticity of plasma cross-section. While local conductivity, as well global confinement, shown inconsistency with predictions, observed toroidal net has successfully explained considering three dimensional geometry available theory. present experimental results indicate that...
The equilibrium of the STP-3(M) reversed field pinch has been studied under various discharge conditions. With increasing magnetic Reynolds number, values reversal ratio F and parameter θ tend to be kept constant by self-organization which is closely related plasma dynamo generating toroidal flux ψ. When we vary poloidal input energy control volt second for fixed condition a circuit, this keeps value K /ψ 2 constant, where helicity, prohibits from attaining helical state.