A5103026948- Particle accelerators and beam dynamics
- Magnetic confinement fusion research
- Plasma Diagnostics and Applications
- Superconducting Materials and Applications
- Particle Accelerators and Free-Electron Lasers
- Acoustic Wave Phenomena Research
- Fusion materials and technologies
- Laser-Plasma Interactions and Diagnostics
- Ionosphere and magnetosphere dynamics
- Vibration and Dynamic Analysis
- Stability and Control of Uncertain Systems
- Vacuum and Plasma Arcs
- Material Properties and Applications
- Nuclear Physics and Applications
- Solar and Space Plasma Dynamics
- Structural Analysis and Optimization
- Topology Optimization in Engineering
- Bird parasitology and diseases
- Composite Structure Analysis and Optimization
- Stability and Controllability of Differential Equations
- Engineering Applied Research
- Dynamics and Control of Mechanical Systems
- Advanced Surface Polishing Techniques
- Coccidia and coccidiosis research
- Control Systems and Identification
Keio University
2024-2025
National Institutes for Quantum Science and Technology
2016-2023
Yokosuka Kyosai Hospital
2023
Funabashi Orthopaedic Hospital
2023
Tokyo University of Science
2022
Tokyo University of Agriculture and Technology
2018-2021
Fusion Academy
2019
Fusion (United States)
2019
Toshiba (Japan)
2018
Tokyo Metropolitan University
2006-2017
The ITER Neutral Beam Test Facility (NBTF), called PRIMA (Padova Research on Megavolt Accelerator), is hosted in Padova, Italy and includes two experiments: MITICA, the full-scale prototype of heating neutral beam injector, SPIDER, full-size radio frequency negative-ions source. NBTF realization exploitation SPIDER MITICA have been recognized as necessary to make future operation injectors efficient reliable, fundamental achievement thermonuclear-relevant plasma parameters ITER. This paper...
The ITER project requires additional heating by two neutral beam injectors, each accelerating to 1 MV a 40 A of negative deuterium ions, deliver the plasma power about 17 MW for one hour. As these requirements have never been experimentally met, it was recognized as necessary setup test facility, PRIMA (Padova Research on Megavolt Accelerator), in Italy, including full-size ion source, SPIDER, and prototype whole injector, MITICA, aiming develop injectors be installed ITER. This realization...
Heating neutral beam (HNB) injectors, necessary to achieve burning conditions and control plasma instabilities in ITER, are characterized by such demanding parameters that a test facility (NBTF) dedicated their development optimization is being realized Padua (Italy) with direct contributions from the Italian government (through Consorzio RFX as host entity) ITER international organization (with kind domestic agencies of Europe, Japan India) technical scientific support various European...
Due to a declining population, Robots are expected become reliable partners for humans in the near future. Such robots need have ability manipulate objects dexterously their hands. This paper proposes an in-hand manipulation method using modal control realizing advanced tasks with tendon-driven robots. Using interaction mode control, position and force can be switched unified manner. Therefore, it is possible intuitively design system when contact object they do not. The proposed uses polar...
Significant progress in the extension of pulse durations powerful negative ion beams has been made to realize neutral beam injectors for JT-60SA and ITER. In order overcome common issues long-pulse production/acceleration ITER, new technologies have developed source MeV accelerator Japan Atomic Energy Agency.
Developments of the large negative ion source have been progressed in high-energy, high-power, and long-pulse neutral beam injector for JT-60 Super Advanced. Countermeasures studied tested critical issues grid heat load voltage holding capability. As acceleration grids, direct interception D- ions was reduced by adjusting beamlet steering. a result, below an allowable level injections. capability, local electric field mitigated tuning gap lengths between large-area grids accelerator....
High power and long-pulse negative ion extractor, which is composed of the plasma grid (PG) extraction (EXG), newly developed toward neutral beam injector for heating current drive future fusion machines such as ITER, JT-60 Super Advanced DEMO reactor. The PG designed to enhance surface production ions efficiently by applying chamfered aperture. efficiency discharge increased a factor 1.3 against that conventional PG. EXG also with thermal analysis upgrade cooling capability long pulse...
The JT-60SA tokamak, being built under the Broader Approach agreement jointly by Europe and Japan, is due to start operation in 2020 expected give substantial contributions both ITER DEMO scenario optimisation. A broad set of preparation activities for an efficient experiments on carried out, involving elaboration Research Plan, advanced modelling various domains, feasibility conception studies diagnostics other sub-systems connection with priorities scientific programme, development...
JT-60SA, the largest tokamak that will operate before ITER, has been designed and built jointly by Japan Europe, is due to start operation in 2020.Its main missions are support ITER exploitation contribute demonstration fusion reactor machine scenario design.Peculiar properties of JT-60SA its capability produce long-pulse, high-β, highly shaped plasmas.The preparation Research Plan, plasma scenarios, producing physics results not only relevant future experiments, but often constitute...
Design techniques for the vacuum insulation have been developed in order to realize a reliable voltage holding capability of multi-aperture multi-grid (MAMuG) accelerators fusion application. In this method, nested multi-stage configuration MAMuG accelerator can be uniquely designed satisfy target within given boundary conditions. The evaluation capabilities each acceleration stages was based on previous experimental results about area effect and effect. Since found extension by total facing...
In order to realize negative ion sources and accelerators be applicable International Thermonuclear Experimental Reactor JT-60 Super Advanced, a large cesium (Cs)-seeded source multi-aperture multi-stage electric acceleration have been developed at Japan Atomic Energy Agency (JAEA). Long pulse production of the beams independently carried out. The long high current has achieved 100 s beam 15 A by modifying source. duration time is increased three times longer than that before modification....
Long pulse acceleration of hydrogen negative ion beams with the power density over 70 MW/m2 and length 100 s has been demonstrated for first time by using a multi-aperture 3-stage accelerator. Such long was achieved integrating design beam optics voltage holding capability to meet requirements JT-60SA. By newly designed accelerator JT-60SA, at 500 kV stably sustained even after 5 g cesium seeded, heat load on each grid reduced below allowable level pulse, less than 5% total power. As result,...
Vacuum insulation on a large size negative ion accelerator with multiple extraction apertures and acceleration grids for fusion application was experimentally examined designed. In the experiment, vacuum characteristics were investigated in JT-60 source >1000 grid surface area of ∼2 m2. The sustainable voltages varied square root gap lengths between grids, decreased number grids. Based obtained results, JT-60SA (super advanced) is designed to produce 22 A, 500 keV D− beams 100 s.
Non-uniformity of the negative ion beams in JT-60 source with world-largest extraction area was improved by modifying magnetic filter from plasma grid (PG) to a tent-shaped filter. The design via electron trajectory calculation showed that expected suppress localization primary electrons emitted filaments and created uniform positive ions atoms parent particles for ions. By filter, uniformity defined as deviation averaged beam intensity reduced 14% PG ∼10% without reduction production.
The superconducting tokamak fusion test device, JT-60SA, was constructed as the Satellite Tokamak project in Broader Approach Program between Japan and EU. During JT-60SA integrated commissioning tests of Nb-Ti equilibrium magnetic field coil EF1 high voltage (∼5 kV) test, power supply current surged suddenly stopped by overcurrent interlock supply. At same time, vacuum cryostat deteriorated, pressure magnet cooling loops increased. After system warmed up, visual inspection revealed that...
Following the 19th IAEA Fusion Energy Conference (Lyon, 2002), (1) three-time progress in formation of ion-confining potential heights ϕc including a record 2.1 kV comparison to those attained 1992–2002 is achieved for tandem-mirror plasmas hot-ion mode with ion temperatures several kiloelectronvolts. (2) The advance gives bases finding remarkable effects radially produced shear electric fields Er, or non-uniform sheared plasma rotation on suppression intermittent vortex-like turbulent...
Voltage holding test on MeV accelerator indicated that sustainable voltage was a half of ideal quasi-Rogowski electrode. It suggested the emission clumps is enhanced by local electric field concentration, which leads to discharge initiation at lower voltage. To reduce concentration in accelerator, gaps between grid supports were expanded and curvature radii support corners increased. After modifications, succeeded sustaining -1 MV vacuum without beam acceleration. However, energy still...
In order to realize neutral beam systems in International Thermonuclear Experimental Reactor whose target is produce a 1 MeV, 200 A/m2 during 3600 s D− ion beam, the electrostatic five-stages negative accelerator so-called “MeV accelerator” has been developed at Japan Atomic Energy Agency. To extend pulse length, heat load of acceleration grids was reduced by controlling trajectory. Namely, deflection due residual magnetic field filter magnet suppressed with newly extractor 0.5 mm off-set...
For the realization of ITER neutral beam (NB) system, a method for achieving acceleration voltage 1 MV vacuum insulated source (VIBS) has been developed. Additionally, design basis insulation also developed by integrating previous empirical scaling holding capability plane and coaxial electrodes with new corner region where locally-concentrated electric field is generated. The clarified that product obtained analysis in vessel was much higher than allowable level. Therefore, order to improve...
A robust stabilization problem is discussed for time delay systems. By introducing an indefinite Riccati-type operator equation systems, a design method stabilizing control law against parametric uncertainties, which occur in lumped-parameter elements and all types of element, obtained. In the derivation law, combined approach taken: internal based on Lyapunov-type with external small-gain theorem. This enables uncertainties systems to be dealt unified way.< <ETX...
High-frequency fluctuations in the ion cyclotron range of frequency (ICRF) are excited magnetically confined plasmas because distortion velocity distribution. In deuterium plasma experiments JT-60U, emission (ICE) detected as magnetic is observed using ICRF antennas pickup loops. The toroidal wave-numbers can be estimated phase differences between signals from antenna elements arrayed direction. this manuscript, ICE due to fusion product (FP) H ions, ICE(H), which identified separately...
In the framework of program for construction 1 MeV-16 MW negative neutral beam injector (NNBI) ITER, a research and development activity on voltage holding in vacuum has been initiated since 2009, aimed at supporting design, construction, NNBI accelerator. For this purpose, prediction model (VHPM) previously developed updated. VHPM, effect anodic electric field cathodic probability breakdown is evaluated by means two exponents: α y. On basis experimental results from different test stands...
Avian trichomonosis is a parasitic infection that affects wide range of avian species, including free-ranging and pet birds worldwide, Trichomonas gallinae has been considered as the only causative agent for decades. The sequence 5.8S ribosomal RNA with internal transcribed spacer (ITS) regions was widely used identifying genotypes determining inter-specific intra-specific diversity. Moreover, Fe-hydrogenase (FeHyd) proposed second genetic marker providing improved resolution strain...