A5069784733- Superconducting Materials and Applications
- Magnetic confinement fusion research
- Fusion materials and technologies
- Physics of Superconductivity and Magnetism
- Particle accelerators and beam dynamics
- Spacecraft and Cryogenic Technologies
- Nuclear Materials and Properties
- Nuclear reactor physics and engineering
- Nuclear Physics and Applications
- Electric Motor Design and Analysis
- Frequency Control in Power Systems
- HVDC Systems and Fault Protection
- Superconductivity in MgB2 and Alloys
- Electromagnetic Launch and Propulsion Technology
- Non-Destructive Testing Techniques
- Heat Transfer and Optimization
- Particle Accelerators and Free-Electron Lasers
- Ionosphere and magnetosphere dynamics
- Numerical methods in engineering
- Mechanical stress and fatigue analysis
- Metal and Thin Film Mechanics
- Heat Transfer and Boiling Studies
- Ultrasonics and Acoustic Wave Propagation
- GaN-based semiconductor devices and materials
- Radiation Detection and Scintillator Technologies
National Institute for Fusion Science
2014-2023
National Institutes of Natural Sciences
1999-2023
The Graduate University for Advanced Studies, SOKENDAI
2021
Tohoku University
1986-2011
Osaka University
2010-2011
Tokai University
2004-2007
Stanley Electric (Japan)
2003-2004
Advanced Science Research Center
1999
The Large Helical Device (LHD) has successfully started running plasma confinement experiments after a long construction period of eight years. During the and machine commissioning phases, variety milestones were attained in fusion engineering which led to first operation, was ignited on 31 March 1998. Two experimental campaigns carried out In campaign, magnetic flux mapping clearly demonstrated nested structure surfaces. conducted with second harmonic 84 82.6 GHz ECH at heating power input...
An innovative winding method is developed by connecting high-temperature superconducting (HTS) conductors to enable efficient construction of a magnet system for the helical fusion reactor FFHR-d1. A large-current capacity HTS conductor, referred as STARS, being incorporation several ideas, such simple stacking state-of-the-art yttrium barium copper oxide tapes embedded in jacket, surrounded electrical insulation inside and an outer stainless-steel jacket cooled helium gas. prototype...
Based on the successful plasma experiments in Large Helical Device (LHD), design activities of LHD-type helical fusion reactor FFHR-d1 are progressing at National Institute for Fusion Science (NIFS). A 100 kA current capacity is required winding conductor under maximum magnetic field ~12 T. The high-temperature superconductor (HTS) a promising option coil conductor. For development such HTS suitable reactor, we fabricated 30 kA-class samples, and excitation tests were successfully carried...
The Fusion Engineering Research Project (FERP) at the National Institute for Science (NIFS) is conducting conceptual design activities LHD-type helical fusion reactor FFHR-d1A.This paper newly defines two options, "basic" and "challenging."Conservative technologies, including those that will be demonstrated in ITER, are chosen basic option which coils made of continuously wound cable-in-conduit superconductors Nb3Sn strands, divertor composed water-cooled tungsten monoblocks, blanket ceramic...
AbstractAbstractFeasibility studies on applying high-temperature superconductors (HTS) to the heliotron-type fusion energy reactor FFHR are being carried out. Using HTS, we consider that three-dimensional helical coils with a ~40 m diameter can be constructed without preparing huge winding machine. A practical method for realizing this concept is proposed. The electromagnetic stress inside coil packs examined using an FEM analysis double-pancake windings. effect of error magnetic field...
Cryogenic oscillating heat pipes (OHPs) have been proposed as a new transfer device for conduction/indirect cooling of high-temperature superconducting (HTS) magnets. OHP is highly effective two-phase which can transport several orders magnitude greater flux than the conduction solids. The performance cryogenic OHPs has intensively examined and results indicate ability dramatically improving HTS Semi-empirical correlations stating thermo-physical properties are introduced based on those room...
In March 1998, the LHD project finally completed its eight year construction schedule. is a superconducting (SC) heliotron type device with R = 3.9 m, ap 0.6 m and B 3 T, which has simple continuous large helical coils. The major mission of to demonstrate high potential currentless helical-toroidal plasmas, are free from current disruption have an intrinsic for steady state operation. After intensive physics design studies in 1980s, necessary programmes SC engineering R&D was carried out, as...
A highly effective cooling technique for a superconducting magnet is proposed by incorporating the cryogenic oscillating heat pipes (OHP) as panels in coil windings. The OHP high performance two-phase transfer device, which can transport several orders of magnitude larger loads than conduction solids. using , Ne, and working fluids have been developed tested at operating temperature ranges 17-25 K (H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML"...
Oscillating heat pipes (OHP) for cryogenic use are being developed to improve the removal characteristics of high-temperature superconducting (HTS) magnets.It is generally difficult remove generated in HTS windings, because thermal diffusivities component materials decrease with an increase operating temperature.Therefore, a local hot-spot can be rather easily magnets, and there possibilities observing degradation properties and/or mechanical damages by stresses.As new cooling technology...
Segmented fabrication of high-temperature superconducting (HTS) coils has been proposed for the helical fusion reactor FFHR-d1; joint-winding and "remountable" (demountable) concept are primary advanced options, respectively. This paper introduces recent research activities on a bridge-type mechanical lap joint HTS Stacked Tapes Assembled in Rigid Structure (STARS) conductors, particularly to be used winding coils, also discusses some technical issues develop reliable joint. First, required...
Heliotron reactors have attractive features for fusion power plants such as having no need current drive and a wide space between the helical coils maintenance of in-vessel components. Their main disadvantage was considered to be necessarily large size their magnet systems. According recent reactor studies based on experimental results in Large Helical Device, major radius plasma 14–17 m with central toroidal field 6–4 T is needed attain self-ignition condition blanket thicker than 1.1 m....
The high-temperature superconducting magnet option is being explored in the conceptual design studies of LHD-type helical fusion reactor FFHR-d1. A 100 kA-class conductor developed by simply stacking REBCO tapes a copper and stainless-steel jacket. One options HTS includes internal insulation so that windings do not require vacuum pressure impregnation process. Innovative winding method huge coils investigated based on segment fabrication half-helical-pitch conductors developing bridge-type...
We have grown blue (480 nm) nitride semiconductor light emitting diodes (LEDs) by plasma-assisted molecular beam epitaxy (MBE) on GaN templates. Packaged devices exhibited output powers up to 0.87 mW at 20 mA forward current. The corresponding external quantum efficiency was 1.68%. Utilizing a combination of direct current (dc) and pulsed electroluminescence measurements it has been demonstrated that low (&lt;20 mA) dc conditions the emission from these is governed combined effects...
The mechanical bridge joint (bridge-type lap joint) of a stacked high-temperature superconducting conductor has been investigated for "remountable" or segment-fabricated magnet. In previous study, resistivities were evaluated experimentally the joints single-layer and double-layer GdBCO coated conductors. However, resistivity increased with an increase in number layers due to nonuniform contact pressure distribution caused by gap misalignment region. this therefore, we aiming at reduction...
Conceptual design activity for the LHD-type helical DEMO reactor FFHR-d1 has been conducted at National Institute Fusion Science under Engineering Research Project since FY2010. In first step of conceptual process, window analysis was using system code HELIOSCOPE by “Design Integration Task Group”. On basis a parametric scan with core plasma based on DPE (Direct Profile Extrapolation) method, point having major radius 15.6 m and averaged magnetic field strength coil winding center 4.7 T...