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22-27 October 2018
Mahatma Mandir Conference Centre
Asia/Kolkata timezone
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Transport characteristics of deuterium and hydrogen plasmas with ion internal transport barrier in LHD

25 Oct 2018, 08:50
20m
Mahatma Mandir Conference Centre

Mahatma Mandir Conference Centre

Gandhinagar (nearest Airport: Ahmedabad), India
Oral EXD - Magnetic Confinement Experiments: Plasma–material interactions; divertors; limiters; scrape-off layer (SOL) EX/5, PPC/1 - TH/3 Integrated Modelling & Transport

Speaker

Prof. Kenichi Nagaoka (National Institute for Fusion Science)

Description

A remarkable achievement of $T_{\rm i0} = 10$ keV with $Z_{\rm eff} = 2$ was obtained in Large Helical Device (LHD). In order to clarify transport characteristics in ion internal transport barrier (ion ITB) formation with isotope effect, a dataset of pure deuterium (D) ($n_{\rm D}/n_{\rm e} > 0.85$) and pure hydrogen (H) ($n_{\rm H}/n_{\rm e} > 0.85$) plasmas for high-ion-temperature (high-$T_{\rm i}$) regime were analyzed, and two mechanisms of transport improvement were characterized. A significant reduction of ion heat transport in D plasmas was observed in comparison between D and H plasmas, indicating non-gyroBohm mass dependence. The dependence of the heat transport on temperature ratio ($T_{\rm e}/T_{\rm i}$) and normalized $T_{\rm i}$-gradient ($R/L_{\rm Ti} = -(R/T_{\rm i})(dT_{\rm i}/dr)$) was investigated in the core region, in which gyrokinetic simulations with GKV code predicts the destabilization of ITG modes [1]. The $T_{\rm e}/T_{\rm i}$ dependence shows ITG-like property, while a significant deviation from the ITG-like property is found in the $R/L_{\rm Ti}$ dependence. Moreover, the density fluctuation is well correlated with the heat transport dependence on $T_{\rm e}/T_{\rm i}$ and $R/L_{\rm Ti}$, indicating suppression of ITG mode in large $R/L_{\rm Ti}$ regime and resultant ion ITB formation. The similarity of instabilities found by GKV indicates that both ITG suppression and isotope effect contribute to production of high-$T_{\rm i}$ plasmas ($T_{\rm i0}\sim10$ keV) with multiple-ion conditions.
Country or International Organization Japan
Paper Number EX/5-1

Primary author

Prof. Kenichi Nagaoka (National Institute for Fusion Science)

Co-authors

Dr Haruhisa Nakano (National Institute for Fusion Science) Dr Hiromi Takahashi (National Institute for Fusion Science) Dr Hiroyuki Yamaguchi (National Institute for Fusion Science) Dr Katsumi Ida (National Institute for Fusion Science) Dr Kenji Tanaka (National Institute for Fusion Science) Mr Kiyofumi Mukai (National Institute for Fusion Science) Prof. MASAYUKI YOKOYAMA (National Institute for Fusion Science) Prof. Masaki Osakabe (National Institute for Fusion Science) Dr Masanori Nunami (National Institute for Fusion Science) Dr Mikirou Yoshinuma (National Institute for Fusion Science) Dr Motoki Nakata (National Institute for Fusion Science) Dr Ryosuke Seki (National Institute for Fusion Science) Dr Sadayoshi Murakami (Departement Nuclear Engineering, Kyoto University) Dr Satoshi Ohdachi (National Institute for Fusion Science) Dr Takahiro Bando (SOKENDAI(Graduate University for Advanced Studies)) Dr Tomohiro Morisaki (National Institute for Fusion Science)

Presentation Materials

Paper