A5065990705- Magnetic confinement fusion research
- Particle accelerators and beam dynamics
- Fusion materials and technologies
- Plasma Diagnostics and Applications
- Ionosphere and magnetosphere dynamics
- Laser-Plasma Interactions and Diagnostics
- Superconducting Materials and Applications
- Solar and Space Plasma Dynamics
- Nuclear Physics and Applications
- Nuclear reactor physics and engineering
- Atomic and Subatomic Physics Research
- Gyrotron and Vacuum Electronics Research
- Ion-surface interactions and analysis
- Astro and Planetary Science
- Atomic and Molecular Physics
- Dust and Plasma Wave Phenomena
- Mass Spectrometry Techniques and Applications
- Electromagnetic Launch and Propulsion Technology
- Radiation Effects in Electronics
- Laser-induced spectroscopy and plasma
- Robotic Path Planning Algorithms
- Advanced Data Storage Technologies
- Radiation Therapy and Dosimetry
- Nuclear physics research studies
- Control and Dynamics of Mobile Robots
National Institute for Fusion Science
2016-2025
The Graduate University for Advanced Studies, SOKENDAI
2017-2024
National Institutes of Natural Sciences
2014-2024
Fusion Academy
2024
Wakayama University
2021-2023
Mitsubishi Heavy Industries (Germany)
2022-2023
Institute of Natural Science
2021
Hokkaido University
2010
A collective Thomson scattering (CTS) diagnostic was developed and used to measure the bulk fast ions originating from 180 keV neutral beams in Large Helical Device (LHD). Electromagnetic waves a gyrotron at 77 GHz with 1 MW power output function as both probe electron cyclotron heating beam. To clarify applicability of frequency band, we investigated dependence receiver beam trajectories plasmas high densities (4–5) × 1019 m−3 low (1–2) m−3. At density, stray radiation component observed...
Understanding of energetic particle (EP) confinement is one the critical issues in realizing fusion reactor.In stellarator/helical devices, research on EP key topics to obtain better by utilizing flexibility three-dimensional magnetic field.Study transport Large Helical Device (LHD) has been performed means escaping diagnostics hydrogen plasma operation.By starting deuterium operation LHD, study EPs progressed remarkably using newly developed comprehensive neutron providing information...
The deuterium operation of the Large Helical Device (LHD) heliotron started in March 7, 2017, after longterm preparation and commissioning works necessary to execute experiment.A comprehensive set neutron diagnostics was implemented accelerate energetic-particle physics research LHD.The calibrated ex-vessel flux monitor indicated that total emission rate first campaign reached 3.3×10 15 n/s inward shifted magnetic field configuration where confinement helically trapped energetic ions is...
The central electron temperature has successfully reached up to 7.5 keV in large helical device (LHD) plasmas with a high-ion of 5 and density m−3. This result was obtained by heating newly-installed 154 GHz gyrotron also the optimisation injection geometry cyclotron (ECH). carried out using ray-tracing code 'LHDGauss', which upgraded include rapid post-processing three-dimensional (3D) equilibrium mapping from experiments. For calculations, LHDGauss can automatically read relevant data...
A new bursting m=1/n=1 instability (m,n: poloidal and toroidal mode numbers) with rapid frequency chirping down has been observed for the first time in a helical plasma intense perpendicular neutral beam injection. This is destabilized peripheral region by resonant interaction between helically trapped energetic ions resistive interchange mode. large radial electric field induced near edge due to enhanced transport of mode, leads clear change flow, suppression microturbulence, triggering an...
The deuterium (D) operation was initiated in the LHD 2017. In first campaign of D experiments, we successfully extended high temperature regime LHD. new record ion (Ti) 10 keV associated with internal transport barrier (ITB) achieved due to several operational optimization. thermal confinement characteristics ITB plasmas were compared between hydrogen and discharges. effective diffusivity ion-ITB found be smaller discharges than that H profiles Ti, electron density, impurity Ti strongly...
Plasma production in stellarators with ion cyclotron heating is complementary to the widely used electron (ECRH). The prospective light minority scenario developed and tried on Uragan-2M Large Helical Device (LHD) had been reexamined at LHD. distinctive feature of this attempt that parameters plasma produced are better than before comparable those by ECRH. This new possibility heating, if it becomes practical, motivates rethinking role stellarator machines.
The discharge scenario of high temperature plasma with a helical configuration has significantly progressed. increase central ion due to the reduction wall recycling was clearly observed. peaking heating profile and charge exchange loss energetic ions play an important role for further improvement heat transport in internal barrier (ITB) core. ITB electron have been successfully integrated superposition centrally focused cyclotron plasma, regime comparable (Ti ~ Te) extended. width formed is...
Alfvén eigenmodes (AEs) destabilized by the neutral beam injection (NBI) in a Large Helical Device experiment are investigated using multi-phase magnetohydrodynamic (MHD) hybrid simulation, which is combination of classical and MHD simulations for fast ions. The ion distribution simulated with NBI, collisions, losses equilibrium magnetic field while simulation takes account interaction between ions an fluid, addition to dynamics. It found that stored energy saturated due AEs at lower level...
The isotope effect on energy confinement time and thermal transport has been investigated for plasmas confined by a stellarator-heliotron magnetic field. This is the first detailed assessment of an in stellarator heliotron. Hydrogen deuterium heated neutral beam injection Large Helical Device have exhibited no significant dependence mass time, which not consistent with simple gyro-Bohm model. A comparison diffusivity dimensionally similar hydrogen terms gyroradius, collisionality, pressure...
In this work, energetic-ion confinement and loss due to driven magnetohydrodynamic modes are studied using comprehensive neutron diagnostics orbit-following numerical simulations for the Large Helical Device (LHD). The flux monitor is employed in order obtain global of energetic ions two installed vertical cameras (VNCs) viewing different poloidal cross-sections utilized measure radial profile ions. A strong helically-trapped energetic-ion-driven resistive interchange mode (EIC) excited...
Abstract Magnetic fusion plasmas, which are complex systems comprising numerous interacting elements, have large uncertainties. Therefore, future reactors require prediction-based advanced control with an adaptive system model and estimation robust to uncertainties in the observations. To address this challenge, we introduced a approach based on data assimilation (DA), describes adaptation state probability distribution. The first implementation of DA-based was achieved at Large Helical...
Enhancement of the output power per gyrotron has been planned in Large Helical Device (LHD). Three 77-GHz gyrotrons with an more than 1 MW have operated. In addition, a high frequency 154 GHz (1 MW/5 s, 0.5 MW/CW) was newly installed 2012, and total injection Electron cyclotron resonance heating (ECRH) reached 4.6 MW. The operational regime ECRH plasma on LHD extended due to upgraded system such as central electron temperature 13.5 keV line-averaged density ne_fir = × 1019 m−3. thermal...
The integrated transport analysis suite, TASK3D-a (Analysis), has been developed to be capable for routine whole-discharge analyses of plasmas confined in three-dimensional (3D) magnetic configurations such as the LHD. dynamic energy balance NBI-heated was made possible first version released September 2012. suite further extended through implementing additional modules neoclassical and ECH deposition 3D configurations. A module also added creating systematic data International...
Time-resolved measurement of triton burnup is performed with a scintillating fiber detector system in the deuterium operation large helical device. The composed head consisting 109 fibers having diameter 1 mm and length 100 embedded aluminum substrate, magnetic registrant photomultiplier tube, data acquisition equipped GHz sampling rate analogies to digital converter field programmable gate array. discrimination level 150 mV was set extract pulse signal induced by 14 MeV neutrons according...
This work presents an upgrade of the FIT3D neutral beam–plasma interaction code, part TASK3D, a transport suite codes, and its application to LHD experiments in framework preparation for first deuterium LHD. The beam injector (NBI) system will be upgraded D injection, efforts have been recently made extend modelling capabilities operations. implemented upgrades enable NBI plasmas are presented, with discussion benchmark models used. In particular, ionization module has modified routine...
Effects of carbon impurities on the thermal confinement properties were discussed for carbon-pellet-injected high-Ti discharges in Large Helical Device (LHD). To clarify their role, amounts introduced into plasmas scanned by varying number injections a discharge or size pellet, and changes with these variations examined. In all cases, strong correlations between densities diffusivities found. Thermal small when greater than certain value, e.g. ∼1.5 × 1017 m3 at r/a ≈ 0.72, diffusivity...
A central ion temperature of 7 keV in a neutral beam injection (NBI)-heated plasma and central-electron 20 an electron cyclotron resonance heating were achieved the Large Helical Device (LHD) using upgraded system with newly installed perpendicular-NB injector gyrotrons. The values Ti Te significantly exceeded 5.6 15 keV, obtained previous experiments, respectively. High-Ti was carbon pellet kinetic-energy confinement improved by factor 1.5. Transport analysis high-Ti plasmas showed that...
Abstract A resistive interchange mode of the <?CDATA $m=1/n=1$ ?> <?MML <mml:math><mml:mstyle displaystyle='false'><mml:mrow><mml:mi>m</mml:mi><mml:mo>=</mml:mo><mml:mn>1</mml:mn><mml:mo>/</mml:mo><mml:mi>n</mml:mi><mml:mo>=</mml:mo><mml:mn>1</mml:mn></mml:mrow></mml:mstyle></mml:math> structure ( $m$ displaystyle='false'><mml:mi>m</mml:mi></mml:mstyle></mml:math> , $n$ displaystyle='false'><mml:mi>n</mml:mi></mml:mstyle></mml:math> : poloidal and toroidal numbers,...
Deuterium experiment was initiated to achieve higher-temperature and higher-density plasmas in March 2017 the Large Helical Device (LHD).The central ion temperature notably increases compared with that hydrogen experiments.However, energeticparticle modes called helically-trapped energetic-ion-driven resistive interchange (EIC) are often excited by intensive perpendicular neutral beam injections on high ion-temperature discharges.The mode leads significant decrease of or limiting sustainment...
Three-dimensional trajectories of incandescent dust particles in plasmas were observed with stereoscopic fast framing cameras a large helical device. It proved that the is located peripheral plasma and most moves along magnetic field lines acceleration direction corresponds to flow. ICRF heated long pulse discharges terminated release amounts from closed divertor region. After experimental campaign, traces exfoliation carbon rich mixed-material deposition layers found Transport investigated...
A reversal of intrinsic torque is observed during the formation an internal transport barrier (ITB) in Large Helical Device. The evaluated from disparity rotation between coinjection and counterinjection changes sign counter to codirection inside ITB after formation. Both propagate inwards. This experiment demonstrates that nondiffusive term momentum sensitive confinement mode heat transport.
The resistive interchange mode destabilized by the resonant interaction with trapped energetic ions is fully suppressed when injected power of electron cyclotron heating exceeds a certain threshold. It shown for first time that complete stabilization energetic-particle-driven without relaxing particle (EP) pressure gradient possible reducing radial width eigenmodes ${\ensuremath{\delta}}_{w}$, especially ${\ensuremath{\delta}}_{w}$ narrows to small enough value relative finite orbit EP.
Abstract Tangential compact neutron emission spectrometer (CNES) based on the Cs 2 LiYCl 6 :Ce with 7 Li-enrichment (CLYC7) scintillator is newly installed in Large Helical Device (LHD). Measurement of energy spectrum was performed using CNES tangential neutral beam (NB) heated deuterium plasma discharges. The Doppler shift according to direction NB injection has been obtained. When fast ions moving away from CNES, lower shifted obtained, whereas upper obtained when toward CNES. almost...
We assess the magnetic field configuration in modern fusion devices by comparing experiments with same heating power, between a stellarator and heliotron. The key role of turbulence is evident optimized stellarator, while neoclassical processes largely determine transport heliotron device. Gyrokinetic simulations elucidate underlying mechanisms promoting stronger ion scale stellarator. Similar plasma performances these suggests that turbulent should both be next step reactor designs.