Isotope effects on transport in LHD

K. Tanaka*, K. Nagaoka, K. Ida, H. Yamada, T. Kobayashi, S. Satake, M. Nakata, T. Kinoshita, Y. Ohtani, T. Tokuzawa, H. Takahashi, F. Warmer, K. Mukai, S. Murakami, R. Sakamoto, H. Nakano, M. Osakabe, T. Morisaki, M. Nunami, Tuomas TalaT. Tsujimura, Y. Takemura, M. Yokoyama, R. Seki, H. Igami, Y. Yoshimura, S. Kubo, T. Shimozuma, T. Akiyama, I. Yamada, R. Yasuhara, H. Funaba, M. Yoshinuma, M. Goto, T. Oishi, S. Morita, G. Motojima, M. Shoji, S. Masuzaki, C. A. Michael, L. N. Vacheslavov

*Corresponding author for this work

    Research output: Contribution to journalArticleScientificpeer-review

    10 Citations (Scopus)

    Abstract

    Isotope effects are one of the most important issues for predicting future reactor operations. Large helical device (LHD) is the presently working largest stellarator/helical device using super conducting helical coils. In LHD, deuterium experiments started in 2017. Extensive studies regarding isotope effects on transport have been carried out. In this paper, the results of isotope effect studies in LHD are reported. The systematic studies were performed adjusting operational parameters and nondimensional parameters. In L mode like normal confinement plasma, where internal and edge transport barriers are not formed, the scaling of global energy confinement time (τE) with operational parameters shows positive mass dependence (M0.27; where M is effective ion mass) in electron cyclotron heating plasma and no mass dependence (M0.0) in neutral beam injection heating plasma. The non-negative ion mass dependence is anti-gyro-Bohm scaling. The role of the turbulence in isotope effects was also found by turbulence measurements and gyrokinetic simulation. Better accessibility to electron and ion internal transport barrier (ITB) plasma is found in deuterium (D) plasma than in hydrogen (H). Gyro kinetic non-linear simulation shows reduced ion heat flux due to the larger generation of zonal flow in deuterium plasma. Peaked carbon density profile plays a prominent role in reducing ion energy transport in ITB plasma. This is evident only in plasma with deuterium ions. New findings on the mixing and non-mixing states of D and H particle transports are reported. In the mixing state, ion particle diffusivities are higher than electron particle diffusivities and D and H ion density profiles are almost identical. In the non-mixing state, ion particle diffusivity is much lower than electron diffusivity. Deuterium and hydrogen ion profiles are clearly different. Different turbulence structures were found in the mixing and non-mixing states suggesting different turbulence modes play a role.

    Original languageEnglish
    Article number094001
    JournalPlasma Physics and Controlled Fusion
    Volume63
    Issue number9
    DOIs
    Publication statusPublished - Sept 2021
    MoE publication typeA1 Journal article-refereed

    Funding

    This work is supported by NIFS Grants NIFS17ULHH013, NIFS18ULHH013, NIFS18KLER045, NIFS18KLPH032, NIFS18KUHL083, NIFS19KLPH038, NIFS17ULRR701, NIFS17ULRR702, NIFS17ULRR801, NIFS17ULRR808, NIFS17ULRR809, NIFS17KLPR036, NIFS16UMLG701, NIFS16ULGG801, NIFS19KLPH038, NIFS17UNTT008, NIFS17KLPR036, NIFS16KNST096, NIFS18KNXN369, NIFS16KNXN315, NIFS18KNST132, NIFS17KLPH031, NIFS17ULHH033, JSPS Grant 16H04620, JSPS Grant 17K14898, JSPS Grant 17K14899, JSPS Grant 15H02336, JSPS Grant 16H02442, JSPS Grant 17H01368, and US DOE under DE-SC0019007 Numerical simulations were performed by Plasma Simulator at NIFS, and by FX100 at Nagoya University, and supported by the NIFS collaborative Research Programs, and partly by the MEXT grant for Post K project: Development of Innovative Clean Energy, Core Design of Fusion Reactor.

    Fingerprint

    Dive into the research topics of 'Isotope effects on transport in LHD'. Together they form a unique fingerprint.

    Cite this