S. Masuzaki
A5030422039- Magnetic confinement fusion research
- Fusion materials and technologies
- Superconducting Materials and Applications
- Plasma Diagnostics and Applications
- Ionosphere and magnetosphere dynamics
- Particle accelerators and beam dynamics
- Nuclear Materials and Properties
- Laser-Plasma Interactions and Diagnostics
- Nuclear reactor physics and engineering
- Solar and Space Plasma Dynamics
- Heat Transfer and Boiling Studies
- Ion-surface interactions and analysis
- Laser-induced spectroscopy and plasma
- Vacuum and Plasma Arcs
- Heat Transfer and Optimization
- Dust and Plasma Wave Phenomena
- Metal and Thin Film Mechanics
- Nuclear Physics and Applications
- Diamond and Carbon-based Materials Research
- Spacecraft and Cryogenic Technologies
- Heat Transfer Mechanisms
- Advanced materials and composites
- Atomic and Molecular Physics
- Engineering Applied Research
- Nuclear Engineering Thermal-Hydraulics
National Institute for Fusion Science
2015-2024
The Graduate University for Advanced Studies, SOKENDAI
2011-2024
National Institutes of Natural Sciences
2014-2024
Kyushu University
2021-2022
Fusion (United States)
2022
Max Planck Institute for Plasma Physics
2018
Max Planck Society
2018
Southwestern Institute of Physics
2013
Nagoya University of Foreign Studies
2013
Nagoya University
1990-2011
A stochastic magnetic boundary, produced by an applied edge resonant perturbation, is used to suppress most large edge-localized modes (ELMs) in high confinement ($H$-mode) plasmas. The resulting $H$ mode displays rapid, small oscillations with a bursty character modulated coherent 130 Hz envelope. transport barrier and core are unaffected the despite threefold drop toroidal rotation. These results demonstrate that boundaries compatible may be attractive for ELM control next-step fusion tokamaks.
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...
Large sub-millisecond heat pulses due to Type-I edge localized modes (ELMs) have been eliminated reproducibly in DIII-D for periods approaching nine energy confinement times (τE) with small dc currents driven a simple magnetic perturbation coil. The current required eliminate all but few isolated ELM impulses during coil pulse is less than 0.4% of plasma current. Based on field line modelling, the fields resonate flux surfaces across most pedestal region (0.9 ⩽ ψN 1.0) when q95 = 3.7 ± 0.2,...
As the finalization of a hydrogen experiment towards deuterium phase, exploration best performance plasma was intensively performed in large helical device. High ion and electron temperatures, Ti Te, more than 6 keV were simultaneously achieved by superimposing high-power cyclotron resonance heating onneutral beam injection (NBI) heated plasma. Although flattening temperature profile core region observed during discharges, one could avoid degradation increasing density. Another key parameter...
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...
The Large Helical Device (LHD) experiments [O. Motojima, et al., Proceedings, 16th Conference on Fusion Energy, Montreal, 1996 (International Atomic Energy Agency, Vienna, 1997), Vol. 3, p. 437] have started this year after a successful eight-year construction and test period of the fully superconducting facility. LHD investigates variety physics issues large scale heliotron plasmas (R=3.9 m, a=0.6 m), which stimulates efforts to explore currentless disruption-free steady under an optimized...
In reduced recycling discharges in the Large Helical Device, a super dense core plasma develops when series of pellets are injected. A region with density as high 4.5 x 10(20) m(-3) and temperature 0.85 keV is maintained by an internal diffusion barrier very high-density gradient. These results may extrapolate to scenario for fusion ignition at relatively low helical devices.
Divertor plasma characteristics in the Large Helical Device (LHD) have been investigated mainly by using Langmuir probes. The three-dimensional structure of helical divertor, which is naturally produced heliotron-type magnetic configuration, clearly seen measured particle and power deposition profiles on divertor plates. These observations are consistent with numerical results field line tracing. flux to plates increases almost linearly averaged density. high-recycling regime detachment,...
The tungsten nanostructure (W-fuzz) created in the linear divertor simulator (NAGDIS) was exposed to Large Helical Device (LHD) plasma for only 2 s (1 shot) study exfoliation/erosion and microscopic modifications due high heat/particle loading under magnetic field conditions. Very fine randomly moved unipolar arc trails were clearly observed on about half of W-fuzz area (6 × 10 mm ). fuzzy surface exfoliated by continuously moving spots even very short exposure time. This is first...
Abstract In state-of-the-art stellarators, turbulence is a major cause of the degradation plasma confinement. To maximize confinement, which eventually determines amount nuclear fusion reactions, turbulent transport needs to be reduced. Here we report observation confinement regime in stellarator that characterized by increased and reduced fluctuations. The transition this driven injection submillimetric boron powder grains into plasma. With line-averaged electron density being kept...
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...
Recent experimental results in the Large Helical Device have indicated that a large pressure gradient can be formed beyond stability criterion for Mercier (high-n) mode. While against an interchange mode is violated inward-shifted configuration due to enhancement of magnetic hill, neoclassical transport and confinement high-energy particle are, contrast, improved by this inward shift. Mitigation unfavourable effects MHD instability has led significant extension operational regime....
It is found that resonant magnetic perturbation (RMP) fields have a stabilizing effect on the radiating edge plasma, realizing stable sustainment of radiative divertor (RD) operation in Large Helical Device (LHD). Without RMP, thermal instability leads to collapse. Divertor power load reduced by factor 3–10 during RMP-assisted RD phase, while maintaining relatively good core plasma confinement with enhancement . has also been demonstrated RMP field itself can initiate transition increasing...
Edge impurity transport has been investigated in the stochastic layer of Large Helical Device (LHD) and scrape-off (SOL) Huan Liuqi-2A (HL-2A) tokamak, as a comparative analysis based on three-dimensional (3D) edge code EMC3-EIRENE carbon emission profile measurement.The 3D simulation predicts screening effect both devices, but also different behavior against collisionality source location between two devices.The difference is caused by geometrical structures magnetic field lines X-point...
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...
The Wendelstein 7-X (W7-X) optimized stellarator fusion experiment, which went into operation in 2015, has been operating since 2017 with an un-cooled modular graphite divertor. This allowed first divertor physics studies to be performed at pulse energies up 80 MJ, as opposed 4 MJ the phase, where five inboard limiters were installed instead of a This, and number other upgrades device capabilities, extension regimes higher plasma density, heating power, performance overall, e.g. setting new...
Abstract In recent deuterium experiments on the large helical device (LHD), we succeeded in expanding temperature domain to higher regions for both electron and ion temperatures. Suppression of energetic particle driven resistive interchange mode (EIC) by a moderate increase is key technique extend high LHD plasmas. We found clear isotope effect formation internal transport barrier A new measure hydrogen fraction was developed order investigate behavior mixing state. The revealed that...
Two significant problems that need to be solved for any future fusion device are heat removal and particle control. A very promising method attack these in tokamaks helical devices is the use of a divertor, providing controlled interaction zone between plasma wall. By carefully designing conditions can created front divertor targets, which lead sufficient reduction power load on targets by strong radiation redistribution. Any solution course needs allow an energy confinement at least...
It has been known for a long time that microscopic dust appears in plasmas fusion devices. Recently it was shown can be responsible the termination of long- discharges. Also, ITER-scale experiments pose safety problems related to its chemical activity, tritium retention and radioactive content. In particular, presence vacuum chamber ITER is one main concerns licensing process. Here we review recent progress understanding different experimental theoretical aspects physics dynamics transport...
Abstract An extended mesh system for EMC3‐EIRENE has been developed to simulate peripheral plasma including the ergodic and divertor leg regions of LHD. Both open closed configurations are available. A series simulations 8MW input power, five different electron densities at LCFS (last flux surface) open/closed were carried out. Approximately 10 times larger neutral pressure was observed under dome structure compared with configuration, which is in good agreement experimental measurements. In...
Modeling of impurity-seeded plasma in Large Helical Device (LHD) is presented for the first time by using three-dimensional transport code EMC3-EIRENE.High and low recycling coefficients impurity ions are assumed to include high absorption rates on wall surfaces due chemical activity neon nitrogen, respectively.Radiation power measured two bolometer systems particle flux divertor probes installed multiple toroidal sections utilized determine amount plasma.The uniformity non-uniformity a...
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...
Abstract In order to clarify the divertor plasma-induced tungsten (W) surface modifications as well irradiation defects effect, two kinds of ITER grade W were exposed large helical device (LHD) deuterium (D) plasma at divertor-leg position. One was iron (Fe) ion irradiated produce defects, and other unirradiated W. The distributions on these clarified by scanning electron microscope (SEM) transmission microscopy (TEM). A co-deposition layer which mainly made up carbon (C) Fe formed private...