N. Asakura
A5037464316- Magnetic confinement fusion research
- Fusion materials and technologies
- Superconducting Materials and Applications
- Nuclear reactor physics and engineering
- Ionosphere and magnetosphere dynamics
- Laser-Plasma Interactions and Diagnostics
- Nuclear Materials and Properties
- Particle accelerators and beam dynamics
- Plasma Diagnostics and Applications
- Nuclear Physics and Applications
- Solar and Space Plasma Dynamics
- Atomic and Molecular Physics
- Dust and Plasma Wave Phenomena
- Laser-induced spectroscopy and plasma
- Photocathodes and Microchannel Plates
- Radiation Detection and Scintillator Technologies
- High-pressure geophysics and materials
- Gas Dynamics and Kinetic Theory
- Fluid Dynamics and Turbulent Flows
- High-Energy Particle Collisions Research
- Vacuum and Plasma Arcs
- Quantum, superfluid, helium dynamics
- Non-Destructive Testing Techniques
- X-ray Spectroscopy and Fluorescence Analysis
- Advanced Sensor Technologies Research
Chiba University
2025
National Institutes for Quantum Science and Technology
2017-2024
Royal Military Academy
2020
Japan Atomic Energy Agency
2007-2016
Lawrence Livermore National Laboratory
1993-2013
Advanced Science Research Center
1997-2008
Centre National de la Recherche Scientifique
2008
Université Sorbonne Paris Nord
2008
Yamagata Research Institute Of Technology
2008
Fujitsu (Japan)
2008
Progress, since the ITER Physics Basis publication (ITER Editors et al 1999 Nucl. Fusion 39 2137–2664), in understanding processes that will determine properties of plasma edge and its interaction with material elements is described. Experimental areas where significant progress has taken place are energy transport scrape-off layer (SOL) particular anomalous scaling, particle SOL plays a major role diverted plasmas main-chamber elements, localized mode (ELM) deposition on mechanism for ELM...
The 'Progress in the ITER Physics Basis' (PIPB) document is an update of 'ITER (IPB), which was published 1999 [1]. IPB provided methodologies for projecting performance burning plasmas, developed largely through coordinated experimental, modelling and theoretical activities carried out on today's large tokamaks (ITER R&D). In IPB, projections (1998 Design) were also presented. pointed some outstanding issues. These issues have been addressed by Participant Teams (the European Union, Japan,...
Analysis of Type I ELMs from ongoing experiments shows that ELM energy losses are correlated with the density and temperature pedestal plasma before crash. The loss normalized to is found correlate across collisionality (ν*ped), decreasing increasing ν*ped. Other parameters affect size, such as edge magnetic shear, etc, which influence volume affected by ELMs. particle influenced this weakly dependent on other parameters. In JET DIII-D, under some conditions, can be observed (`minimum'...
Abstract The JET 2019–2020 scientific and technological programme exploited the results of years concerted engineering work, including ITER-like wall (ILW: Be W divertor) installed in 2010, improved diagnostic capabilities now fully available, a major neutral beam injection upgrade providing record power 2019–2020, tested technical procedural preparation for safe operation with tritium. Research along three complementary axes yielded wealth new results. Firstly, plasma delivered scenarios...
Spontaneous formation of an internal transport barrier was observed associated with improved confinement in the high-${\mathrm{\ensuremath{\beta}}}_{\mathit{p}}$ discharges JT-60U tokamak. The radial location found to be on q=3 surface. A fast magnetohydrodynamic event localized at triggered subsequent edge that resulted further improvement. In these discharges, a high poloidal rotation velocity significantly exceeded prediction present neoclassical theory also r/a=0.8.
Recent research in scrape-off layer (SOL) and divertor physics is reviewed; new existing data from a variety of experiments have been used to make cross-experiment comparisons with implications for further ITER. Studies the region near separatrix addressed relationship profiles turbulence as well scaling parallel power flow. Enhanced low-field side radial transport implicated driving flows inboard side. The medium-n nature edge localized modes (ELMs) has elucidated measurements determined...
The design progress in a compact low aspect ratio (low A ) DEMO reactor, ‘SlimCS’, and its issues are reported. study focused mainly on the torus configuration including blanket, divertor, materials maintenance scheme. For continuity with Japanese ITER-TBM, blanket is based water-cooled solid breeder blanket. vertical stability of elongated plasma high beta access, segmented into replaceable permanent blankets sector-wide conducting shell arranged inbetween these blankets. numerical...
This paper summarizes the evolution of Japanese DEMO design studies in a retrospective manner by highlighting efforts to resolve critical issues on DEMO. Japan is currently working conceptual study steady-state (JA DEMO) with major radius Rp 8.5 m and fusion power Pfus 1.5 2 GW based water-cooled solid breeding blanket pressurized water reactor condition (290ºC 325ºC, 15.5 MPa). Such lower allows find realistic solutions for divertor heat removal. Recognizing that removal one most...
Abstract Since the publication of review Progress in ITER Physics Basis (PIPB) 2007, significant progress has been made understanding processes at plasma-material interface. This review, part ITPA Nuclear Fusion Special Issue On Path to Burning Plasma Operation , presents these developments, focusing on key areas such as physics plasma exhaust, interactions, and properties plasma-facing materials their evolution under exposure. The coordinated efforts Topical Group Scrape-Off Layer Divertor...
Rseduction of heat loading appropriate for the plasma facing components such as divertor is crucial a fusion reactor. Power handling by large radiative power loss has been studied in long pulse ELMy H-mode discharges on JT-60U (τ d = 30–35 s). Case 1 argon (Ar) seeding into standard plasmas, where radiation confined region main caused change ELM characteristics from Type-I to Type-III. 2 combination Ar and nitrogen (Ne) gas plasmas with an internal transport barrier (ITB). For case 1, both...
Power exhaust to the divertor and conceptual design have been investigated for a steady-state DEMO in Japan with 1.5 GW-level fusion power major radius of 8.5 m, where plasma parameters were revised appropriate impurity seeding scenario. A system code survey Ar suggested volume-averaged density, concentration from main = 205–285 MW. The simulation (SONIC) was performed leg length 1.6 m fixed edge 250 MW total radiation fraction at edge, SOL ( 0.8), as first step investigate size geometry. At...
The objective of thermonuclear fusion consists producing electricity from the coalescence light nuclei in high temperature plasmas. most promising route to envisages confinement such plasmas with magnetic fields, whose studied configuration is tokamak. Disruptions are catastrophic collapses affecting all tokamak devices and one main potential showstoppers on a commercial reactor. In this work we report how, deploying innovative analysis methods thousands JET experiments covering isotopic...
In the first four years of LHD experiment, several encouraging results have emerged, most significant which is that MHD stability and good transport are compatible in inward shifted axis configuration. The observed energy confinement at this optimal configuration consistent with ISS95 scaling an enhancement factor 1.5. over smaller heliotron devices attributed to high edge temperature. We find plasma average beta 3% stable configuration, even though theoretical conditions Mercier modes...
Edge localized mode (ELM) measurements in many tokamaks, including ASDEX-Upgrade, DIII-D, JET, JT-60U and MAST, are reviewed, which includes progress experimental observations at the plasma edge region by means of fast-time resolved diagnostics with high precision, such as scanning probe, radial interferometer chord, BES tangentially viewing fast-gated camera midplane. ELM dynamics data show that majority particle energy transport should be dominated ion convection physics associated...
QUEST focuses on the steady state operation of spherical tokamak by controlled PWI and electron Bernstein wave current drive. One main purposes is an achievement long duration discharge with MW-class injected power. As result, should be operated in challenging region heat particle handling. To do handling, high temperature all metal wall up to 623 K closed divertors are planned, which realize steady-state under recycling ratio, R = 1. This a dispensable check DEMO, because pumping avoided as...
This paper describes the recent progress in divertor simulation research using GAMMA 10/PDX tandem mirror towards development of divertors fusion reactors. During a plasma flow generation experiment end cell 10/PDX, ICRF heating anchor successfully extended particle flux up to 3.3 × 1023 m2 s−1. Superimposing short pulse ECH also attained maximum heat ~30 MW m−2. We have succeeded achieving and characterizing detachment high-temperature plasma, which is equivalent SOL tokamaks, by...
Power exhaust for a 3 GW class fusion reactor with an ITER-sized plasma was investigated by enhancing the radiation loss from seeding impurity. The impurity transport and detachment were simulated under Demo divertor condition using integrated code SONIC, in which Monte-Carlo code, IMPMC, can handle most kinetic effects on ions original formula. simulation results of species low Z (neon) to high (krypton) length exhausted power 500 MW 460 MW, fixed core–edge boundary 7 × 1019 m−3 at first...
The Joint Special Design Team for Fusion DEMO was organized in 2015 to enhance Japan's design activity and coordinate relevant research development (R&D) toward DEMO. This paper presents the fundamental concept of its key components with main arguments on strategy. Superconducting magnet technology toroidal field coils is based ITER scheme where a cable-in-conduit Nb3Sn conductor inserted groove radial plate. Development cryogenic steel higher strength major challenge magnet. Divertor study...