Extension of high <i>T</i>e regime with upgraded electron cyclotron resonance heating system in the Large Helical Device

Transport and confinement characteristics, and microinstabilities for high-T i /T e and high-T e /T i isotope plasmas in Large Helical Device are explored by using the gyrokinetic Vlasov simulation GKV with hydrogen isotope ions and real-mass kinetic electrons. The experimental data indicate that the thermal diffusivity is reduced in the deuterium-dominated plasmas, where the deviation from the gyro-Bohm scaling in the overall tendency and the strong anomaly of the electron heat transport are identified. Linear gyrokinetic analyses identify that the growth rates of the ion temperature gradient(ITG) and trapped electron mode(TEM) instabilities in the deuterium plasmas are reduced due to the change in the profile gradients and/or the isotope ion mass, and the radial dependence of the mixing-length diffusivity is qualitatively consistent with the experimental tendency. Also, TEM-like turbulent fluctuations are examined by the using the phase contrast imaging(PCI) measurement and the linear gyrokinetic calculation for the high-T e /T i deuterium plasma.

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“…The details about the typical experimental setups for NBI-and ECRH-sustained plasmas are shown in, e.g., Refs. [14,15,16,7,8].…”

Section: Nbi-sustained and Ecrh-sustained Isotope Plasma Experimentsmentioning

confidence: 99%

Gyrokinetic microinstability analysis of high-T _i and high-T _e isotope plasmas in Large Helical Device

Nakata

Nagaoka

Tanaka

et al. 2018

Plasma Phys. Control. Fusion

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“…An understanding of the applicability of the neoclassical predictions to these plasmas, as well as the dynamics involved in developing the electron root region, is being actively pursued at LHD. 3, [5][6][7][8][9][10] In this paper, the analysis of high-T e plasmas is extended by looking at the detailed evolution of a CERC discharge which is produced using only ECH heating. The analysis of the transport and radial electric field structure is performed with the task3D transport suite along with measurements of the perpendicular flow velocity from the high resolution x-ray crystal spectrometer (XICS) 2 .…”

Section: Introductionmentioning

confidence: 99%

Investigation of ion and electron heat transport of high-T_eECH heated discharges in the large helical device

Pablant

Satake

Yokoyama

et al. 2016

Plasma Phys. Control. Fusion

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An analysis of the radial electric field and heat transport, both for ions and electrons, is presented for a high-T e electron cyclotron heated (ECH) discharge on the Large Helical Device (LHD). Transport analysis is done using the task3d transport suite 1 utilizing experimentally measured profiles for both ions and electrons. Ion temperature and perpendicular flow profiles are measured using the recently installed x-ray imaging crystal spectrometer diagnostic (XICS) 2 , while electron temperature and density profiles are measured using Thomson scattering. The analysis also includes calculated ECH power deposition profiles as determined through the travis ray-tracing code. This is the first time on LHD that this type of integrated transport analysis with measured ion temperature profiles has been performed without NBI injection, allowing the heat transport properties of plasmas with only ECH heating to be more clearly examined. For this study, a plasma discharge is chosen which develops a high central electron temperature (T eo = 9keV) at moderately low densities (n eo = 1.5 × 10 19 m −3). The experimentally determined transport properties from task3d are compared to neoclassical predictions as calculated by the gsrake and fortec-3d codes. The predicted electron fluxes are seen to be an order of magnitude less than the measured fluxes, indicating that electron transport is largely anomalous, while the neoclassical and measured ion heat fluxes are of the same magnitude. Neoclassical predictions of a strong positive ambipolar electric field (E r) in the plasma core are validated through comparisons to perpendicular flow measurements from the XICS diagnostic. This provides confidence that the predictions are producing physically meaningful results for the particle fluxes and radial electric field, which are a key component in correctly predicting plasma confinement.

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“…The operation scenario of the ECRH injection system optimally preset before a discharge can result in a high performance plasma [4]. In addition, feedback control of the ECRH injection system set to an optimal target in real time can create a desired power deposition and reduce the stray radiation in the vessel during a long-pulse discharge [5].…”

Section: Introductionmentioning

confidence: 99%

Optimization of Incident EC Wave Polarization in Real-Time Polarization Scan Experiments on LHD

Tsujimura

Mizuno

Makino

et al. 2016

Plasma and Fusion Research

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Real-time polarization scan experiments were performed on the Large Helical Device (LHD) to search an optimal incident wave polarization for electron cyclotron resonance heating. The obtained optimal polarization state to maximize the power absorption to the LHD plasma is compared with the ray-tracing code that includes mode content analyses, which indicates that the calculated results are generally in good agreement with the experimental results. The analyses show that optimal coupling to plasma waves requires a fine adjustment for an incident wave polarization even for perpendicular injection due to the finite density profile and the magnetic shear at the peripheral region.

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Extension of high Te regime with upgraded electron cyclotron resonance heating system in the Large Helical Device

Cited by 31 publications

References 51 publications

Gyrokinetic microinstability analysis of high-T _i and high-T _e isotope plasmas in Large Helical Device

Gyrokinetic microinstability analysis of high-T _i and high-T _e isotope plasmas in Large Helical Device

Investigation of ion and electron heat transport of high-T_eECH heated discharges in the large helical device

Optimization of Incident EC Wave Polarization in Real-Time Polarization Scan Experiments on LHD

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Extension of high Te regime with upgraded electron cyclotron resonance heating system in the Large Helical Device

Cited by 31 publications

References 51 publications

Gyrokinetic microinstability analysis of high-T i and high-T e isotope plasmas in Large Helical Device

Gyrokinetic microinstability analysis of high-T i and high-T e isotope plasmas in Large Helical Device

Investigation of ion and electron heat transport of high-TeECH heated discharges in the large helical device

Optimization of Incident EC Wave Polarization in Real-Time Polarization Scan Experiments on LHD

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Product

Resources

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Gyrokinetic microinstability analysis of high-T _i and high-T _e isotope plasmas in Large Helical Device

Gyrokinetic microinstability analysis of high-T _i and high-T _e isotope plasmas in Large Helical Device

Investigation of ion and electron heat transport of high-T_eECH heated discharges in the large helical device