A5003344459- Magnetic confinement fusion research
- Plasma Diagnostics and Applications
- Fusion materials and technologies
- Ionosphere and magnetosphere dynamics
- Laser-Plasma Interactions and Diagnostics
- Metal and Thin Film Mechanics
- Diamond and Carbon-based Materials Research
- Superconducting Materials and Applications
- Plasma Applications and Diagnostics
- High voltage insulation and dielectric phenomena
- Particle accelerators and beam dynamics
- Electrostatic Discharge in Electronics
- Laser-induced spectroscopy and plasma
- Magnetic properties of thin films
- Solar and Space Plasma Dynamics
- Magnetic Properties and Applications
- Plasmonic and Surface Plasmon Research
- Ion-surface interactions and analysis
- Aerosol Filtration and Electrostatic Precipitation
- Electrohydrodynamics and Fluid Dynamics
- Nuclear Materials and Properties
- Cellular and Composite Structures
- Crystallization and Solubility Studies
- Silicon Carbide Semiconductor Technologies
- X-ray Diffraction in Crystallography
University of Hyogo
2014-2023
Ibaraki Prefectural Central Hospital
2023
Tokyo Metropolitan University
2023
Yokohama National University
2021
Tokyo Institute of Technology
2018-2019
Pioneer (United States)
2018
Chiba Institute of Technology
2016-2018
Renewable Energy Systems (United Kingdom)
2018
Gifu University
2018
Tohoku University
1989-2017
Error field (or externally applied helical field) penetration is studied numerically based on the two fluids equations. It shown that there a minimum in required amplitude when frequency same as mode being determined by both background equilibrium plasma rotation and diamagnetic drift. The threshold significantly increases deviates from can become asymmetric sides of due to parallel heat transport. After nonlinear saturated island width found be smaller for larger electron drift frequency.
Effects of ambient humidity and temperature on partial discharge (PD) characteristics in twisted pairs with conventional nanocomposite enameled magnet wires have been investigated. Measurements the PD inception voltage (PDIV) apparent charge were performed by applying an AC sinusoidal waveform 60 Hz to pair. The observed PDIV this study can be classified into following three behaviors. First, both decreases increasing relative (RH) at low temperature. Secondly, slightly increases when RH...
The first results of the Dynamic Ergodic Divertor in TEXTOR, when operating m/n=3/1 mode configuration, are presented. deeply penetrating external magnetic field perturbation this configuration increases toroidal plasma rotation. Staying below excitation threshold for m/n=2/1 tearing mode, rotation is always direction current, even if projection rotating opposite direction. observed consistent with a radial electric field, generated by an enhanced electron transport ergodic layers near...
Sequential exposures of W surfaces to steady-state and pulsed (∼0.5 ms) plasmas have been performed in a linear divertor plasma simulator magnetized coaxial gun investigate effects D blisters, nano-sized He bubbles, He-induced fuzz on surface cracking by loads. Surface cracks appeared samples containing blisters or bubbles following 10 shots at ∼0.5 MJ/m2 per shot, while mirror-polished sample with no pre-plasma exposure did not exhibit after similar transient exposures. Note that the is...
The ergodization of the magnetic field lines imposed by dynamic ergodic diverter (DED) in TEXTOR can lead both to confinement improvement and deterioration. cases substantial are resonant ways related particular conditions which flux tubes starting at $X$ points induced islands connected with wall. This opening process is a characteristic modification heat deposition pattern divertor target plate leads increase steepening core plasma density pressure. tentatively attributed electric...
The magnetic field penetration process into a magnetized plasma is of basic interest both for physics and astrophysics. In this context special measurements on the amplification are performed by Hall probe dynamic ergodic divertor (DED) TEXTOR tokamak data interpreted two-fluid model. It observed that growth forced reconnection rotating DED accompanied change fluid rotation. differential rotation frequency between plays an important role in excitation tearing modes. momentum input from to...
Experiments to investigate transport properties under the influence of dynamic ergodic divertor (DED) on TEXTOR are discussed. Relativistic runaway electrons applied for studying ergodization such as enhanced loss. The causes an loss rate; this is higher low relativistic than highly ones, in good agreement with particle orbit mapping. Edge can be controlled by DED perturbation: limiter H-mode plasmas ELM-like and heat bursts associated formation edge pressure gradients mitigated 6/2...
We investigated the characteristics of partial discharge (PD) with twisted enameled wires by optical emission spectroscopy (OES) in atmospheric humid air. The electric field strength gap during discharges was estimated from intensity ratio spectrum bands nitrogen molecules obtained OES. It found that increased when increasing relative humidity, and rate different depending on temperature. increase pair could be related to a reduction PD inception voltage (PDIV) observed experiment. PDIV...
Recently, the dynamic ergodic divertor (DED) of TEXTOR has been studied in an m/n = 3/1 set-up which is characterized by a relatively deep penetration perturbation field. The field creates (a) helical divertor, (b) pattern and/or (c) excitation tearing modes, depending on whether DED current static, rotating co-current direction or counter-current direction. Characteristic properties such as high recycling regime enhanced shielding have studied. A strong effect ergodization spin up plasma...
The concept of the dynamic ergodic divertor (DED) is based on plasma edge ergodization by a resonant perturbation. Such closely related to helical or island divertors in stellerators. base mode DED perturbation field can be m/n = 12/4, 6/2 3/1. 3/1 with its deep penetration provides excitation tearing modes. This topic was presented elsewhere. In this contribution we concentrate properties DED. We report characterization topology, transport fields, impurity and density limit behaviour.The...
The dynamic ergodic divertor (DED) on the TEXTOR tokamak allows for reproducible destabilization of m/n = 2/1 tearing mode which is phase locked to external static or rotating perturbation field. In combination with its flexible heating systems (co- and counter-neutral beam injection, ion cyclotron resonance heating, electron (ECRH) steerable launcher) dedicated experiments study onset, properties large islands stabilization can be performed. dependence excitation threshold (field...
Solvothermal synthesis under supercritical conditions (400 degrees C) and high autogenous pressure (about 40 MPa), has been carried out for the direct preparation of nanocrystalline powders CeO2, Ce(0.85)Zr(0.15)O2, Ce(0.75)Zr(0.25)O2, Ce(0.65)Zr(0.35)O2 Ce(0.5)Zr(0.5)O2 which are characterized applications as catalysts oxygen storage in automotive catalysis. The was presence polyethylene glycol water. For characterization, x-ray diffraction (XRD), transmission electron microscopy (TEM),...
A compact-sized magnetized coaxial plasma gun (MCPG) with a single discharge stage is developed in order to simulate transient heat loads such as type I edge-localized modes (ELMs) ITER. The MCPG produces hydrogen plasmas an electron density of 1- 4 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">21</sup> m xmlns:xlink="http://www.w3.org/1999/xlink">-3</sup> , ion energy 15 eV and pulsewidth 0.5 ms. It found that the absorbed measured by...
Fractal structure of the edge turbulence and enhanced turbulent transport have been studied in tokamak HYBTOK-II with a variation rotating helical magnetic field (RHF) frequency range 5–30 kHz. Edge fluctuations non-Gaussian statistics caused by intermittent bursts time scale 40–100 µs. The RHF has selective effect on fractal flux, demonstrating control process. A delayed synchronization resonant drift wave modes is considered as candidate mechanism to explain dependence frequency.
The error-field penetration process of the dynamic ergodic divertor (DED) on TEXTOR tokamak has been investigated analytically in terms a single fluid MHD model with finite plasma resistivity and viscosity cylindrical geometry. linear produces localization induced current at resonance surface predicts vortex structure velocity field near layer. Moreover, effects Alfvén for are identified by two peaks radial profiles perturbed toroidal magnetic flux when relative rotation between DED rotating...
Penetration processes of rotating helical magnetic perturbation (RHMP) into tokamak plasmas have been studied on a small device HYBTOK-II for dynamic ergodic divertor experiment preparing in TEXTOR. The radial profiles RHMP the plasma measured by inserting probes plasma. penetration has discussed using observed profile based growth islands (i.e. tearing mode). In case low Doppler-shifted frequency from plasma, amplification due to spatial modification current found. A large produces an...
The inactivation of Bacillus atrophaeus spores by a dielectric barrier discharge (DBD) plasma in atmospheric humid air was investigated order to develop low-temperature, low-cost, and high-speed sterilization technique. biological indicators covered with Tyvek sheet were set just outside the DBD region, where temperature humidity as gas precisely controlled an environmental test chamber. results show that B. found be dependent strongly on humidity, completed within 15 min at relative 90% 30...
We studied magnetic properties by applying electric voltage (Vapp) to FePt/MgO stacks with different FePt thicknesses (tFePt), where tFePt was varied in the range from 0.6 1.5?nm. The change coercivity (Hc) became remarkable when reduced, and a Hc of 45?Oe achieved for tFePt?=?0.6?nm changing Vapp +5 ?13?V. However, resistance anomalous Hall effect remained almost constant regardless Vapp. These experimental results suggest possibility interface anisotropy between MgO being modulated present...
The melting and evaporation of target materials such as tungsten, due to the enormous plasma heat flux, are not compatible with realization ITER (International Thermonuclear Experimental Reactor) nuclear fusion reactor designs. Nitrogen gas seeding has recently been considered an effective radiator for edge divertor boundary plasmas protect plate from overheating. Although compatibility nitrogen tokamak discharge operation was obtained in current tokamaks, effects on plasma-facing...