A5001211069- Magnetic confinement fusion research
- Particle accelerators and beam dynamics
- Gyrotron and Vacuum Electronics Research
- Ionosphere and magnetosphere dynamics
- Superconducting Materials and Applications
- Plasma Diagnostics and Applications
- Pulsed Power Technology Applications
- Solar and Space Plasma Dynamics
- Laser-Plasma Interactions and Diagnostics
- Particle Accelerators and Free-Electron Lasers
- Pediatric Urology and Nephrology Studies
- Fusion materials and technologies
- Kidney Stones and Urolithiasis Treatments
- Body Composition Measurement Techniques
- Ureteral procedures and complications
- Nutrition and Health in Aging
- Sports injuries and prevention
- Renal and Vascular Pathologies
- Lower Extremity Biomechanics and Pathologies
- Fluid Dynamics and Turbulent Flows
- Oceanographic and Atmospheric Processes
- Atomic and Subatomic Physics Research
- Organ Donation and Transplantation
- Surface Roughness and Optical Measurements
- Muscle activation and electromyography studies
Nagoya City University
2023-2025
Japan Sport Council
2017-2023
Chiba University
2023
Tokyo Keizai University
2023
Japan Society for the Promotion of Science
2017-2018
Nagoya University
1984-2017
Kanazawa University
1990-2012
Institute of Applied Physics
2007
National Institute for Fusion Science
1990-1991
National Institutes of Natural Sciences
1990-1991
Older individuals have been shown to present muscle atrophy in conjunction with increased fat fraction some muscles. The proportion of and connective tissue within the skeletal can be estimated from axial B-mode ultrasound images using echo intensity (EI). EI was used calculate index quality. Walking, home-based weight-bearing resistance training, its combinations are considered simple, easy, practical exercise interventions for older adults. purpose this study quantify effects walking...
Ion-Bernstein-wave heating is investigated in the JIPPT-II-U tokamak plasma, ${\overline{n}}_{e}\ensuremath{\simeq}1.5\ifmmode\times\else\texttimes\fi{}{10}^{13}$ ${\mathrm{cm}}^{\ensuremath{-}3}$, ${T}_{e0}\ensuremath{\simeq}700$ eV, and ${T}_{i0}\ensuremath{\simeq}300$ eV for ${P}_{\mathrm{rf}}\ensuremath{\lesssim}100$ kW. When $\frac{3}{2}{\ensuremath{\Omega}}_{\mathrm{H}}$ layer placed near plasma minor axis, bulk-hydrogen-ion temperature shows a significant rise,...
In a circular cross-section plasma bounded by limiter, the H-mode transition is triggered rapid rampdown in current during auxiliary heating, even case when edge electron temperature gradually decreases prior to transition. This result suggests that governed enhancement of magnetic shear near edge, associated with radial modification current-density profile.
Toroidal plasma rotation driven not by the momentum input but electric field induced loss of ions has been observed for plasmas heated perpendicular neutral beam injection. The is found to increase in direction opposite current when are ion cyclotron resonance frequency waves. quantitatively consistent with that inferred from ambipolarity particle fluxes.
Current drive by fast magnetosonic waves is successfully performed in the JIPP T-IIU tokamak means of a four-element dipole antenna array with Faraday shield. A plasma current about 50 kA sustained an rf power 80 kW low-density (3 \ifmmode\times\else\texttimes\fi{} ${10}^{12}$ ${\mathrm{cm}}^{\ensuremath{-}3}$) efficiency comparable to that slow-wave drive. density limit for observed, contrary theoretical expectations based on linear wave propagation.
Ion Bernstein Wave (IBW) heating has been examined on the JIPP T-IIU tokamak under two different conditions referred to as Mode-I and Mode-II. In regime, a wave is launched an IBW branch between third fourth cyclotron harmonics of deuterium ions. Mode-II second harmonics. These modes show quite characteristics. The causes this difference are analysed by using simple model determine k|| spectrum excited applying ray tracing code. connection with experiment discussed in previous report (1985),...
In the JIPP T-IIU tokamak an experiment to demonstrate feasibility of fast wave current drive using five loop antennas has been successfully carried out with a relatively high density plasma (ωpe2/ωce2∼5). The RF frequency is 40 MHz and toroidal field 2 kG, which corresponds ω = 13ωcH. conducted in range e ∼ × 1018 m−3 where only can propagate, eliminating possibility slow drive. This two orders magnitude higher than limit predicted for dependence efficiency on relative phase difference Δφ...
The coupling of ICRF power from a slow-wave antenna to plasma with finite temperature is examined. A heuristic model, allowing explicit representations ion Bernstein waves, fast waves and slow used clarify how the partitioned into various wave energy fluxes. This model complemented quantitatively by more elaborate realistic computer model. It shown that such antennas can be highly efficient in transferring most directly only very small fraction going waves. potentiality this scheme for...
The paper discusses the results of a heating experiment in ion cyclotron range frequencies (ICRF) conducted on JIPP T-IIU device with five-element antenna array. This system provides precisely shaped k∥, spectra which vary according to relative phasing angle neighbouring antennas, Δφ. In experiment, Δφ is scanned close pitch and it found that electron efficiency drastically improved = π lowest obtained 0. observation analysed by calculating k∥ then power deposition profiles using ray tracing...
The H-mode, an improved confinement regime, was attained recently in JIPP T-IIU high power heating experiments, a limiter configuration without any shaping of the plasma cross-section. This H-mode is unusual because it obtained with ion cyclotron range frequencies (ICRF). It also combined ICRF and neutral beam injection (NBI) heating. threshold level alone similar to or less than that case. dependence on various parameters has been studied. increases current insensitive density, there...
A series of experiments has been conducted on the JIPP TII-U tokamak since 1989, using newly constructed 130 MHz radiofrequency system. It predicted theoretically that fast wave in this frequency range interacts weakly with particles. Two mechanisms absorption have identified experiment: electron Landau damping/transit time damping and 3rd harmonic ion cyclotron heating. The former mechanism is intimately connected current drive latter can provide a new regime plasma heating or possible...
Spectroscopic investigations of iron-ion line radiation (Fe x--xxiv) in the extreme-ultraviolet region have been carried out during ion cyclotron resonance frequency (ICRF) heating experiments JIPP T-II-U tokamak, at Japanese Institute Plasma Physics (JIPP), Nagoya University, Nagoya. The central-chord radiances lines were observed to increase ICRF heating. After radiance highest ionization stage attained peak toward end heating, lower stages attain their peaks successively later times....
In the JIPP T-IIU tokamak, a high power ICRF heating experiment has been conducted, up to an extremely density (∼2 MW·m−3), with total RF of PRF = 2 MW. Great attention initially paid problem impurities, and it found that (a) adoption low Z materials for limiter, (b) in situ carbon coating (i.e. carbonization) (c) adequate gas puffing synchronized pulse are very effective suppressing radiation loss. With these methods, remarkable reduction metal impurities (especially iron impurity)...
High-power broad-band millimeter-wave radiation is emitted from a plasma in strong Langmuir turbulence state driven by an intense relativistic electron beam. We measured directivity and spectrum of this with filter-bank spectrometer, heterodyne filter-waveguide-combination spectrometer covering 18-140 GHz. The measurement indicated that the was relativistically beamed. observed spectra were nearly flat up to about 40 GHz declined steeply above Discussion given on experimental results...
Experiments on four-stage autoacceleration were carried out to generate a subnanosecond, intense relativistic electron beam (IREB). An annular with energy of 500 keV, current 5 kA, and pulse length 12 ns was injected into series four coaxial cavities decreasing lengths. The the most accelerated part electrons 1.1 MeV 0.8 ns, respectively. transmission line theory that used explain single-stage process found be applicable multistage process.