Monte-Carlo Simulation of Neoclassical Transport in Magnetic Islands and Ergodic Regions

Ryutaro KANNO; Masanori NUNAMI; Shinsuke SATAKE; Hisanori TAKAMARU; Yukihiro TOMITA; Keisuke NAKAJIMA; Masao OKAMOTO; Nobuyoshi OHYABU

doi:10.1585/pfr.3.S1060

Regular Articles

Monte-Carlo Simulation of Neoclassical Transport in Magnetic Islands and Ergodic Regions

Ryutaro KANNO, Masanori NUNAMI, Shinsuke SATAKE, Hisanori TAKAMARU, Yukihiro TOMITA, Keisuke NAKAJIMA, Masao OKAMOTO, Nobuyoshi OHYABU

Author information

Ryutaro KANNO
National Institute for Fusion Science, Toki 509-5292, Japan
Department of Fusion Science, Graduate University for Advanced Studies, Toki 509-5292, Japan
Masanori NUNAMI
Institute of Laser Engineering, Osaka University, Suita 565-0871, Japan
Shinsuke SATAKE
National Institute for Fusion Science, Toki 509-5292, Japan
Hisanori TAKAMARU
Department of Computer Science, Chubu University, Kasugai 487-8501, Japan
Yukihiro TOMITA
National Institute for Fusion Science, Toki 509-5292, Japan
Department of Fusion Science, Graduate University for Advanced Studies, Toki 509-5292, Japan
Keisuke NAKAJIMA
Department of Fusion Science, Graduate University for Advanced Studies, Toki 509-5292, Japan
Masao OKAMOTO
Department of Computer Science, Chubu University, Kasugai 487-8501, Japan
Nobuyoshi OHYABU
National Institute for Fusion Science, Toki 509-5292, Japan
Department of Fusion Science, Graduate University for Advanced Studies, Toki 509-5292, Japan

Keywords: collisional transport, edge plasma, chaotic field line, stochastic analysis, diffusion process, δf simulation

JOURNAL FREE ACCESS

2008 Volume 3 Pages S1060

DOI https://doi.org/10.1585/pfr.3.S1060

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Abstract

It is shown in Large Helical Device experiments that transport modeling based on only fluid description is insufficient to express edge transport phenomena in and around a magnetic island with lower collisionality. Furthermore, in recent tokamak experiments, it is found that the so-called stochastic diffusion theory based on “field line diffusion” overestimates the radial energy transport in collisionless edge plasma affected by resonant magnetic perturbations, though the perturbations induce a chaotic behavior in the field lines. These results imply that conventional modeling of edge transport should be reconsidered for a lower collisionality case. A simulation study of neoclassical transport in magnetic islands and ergodic regions is attempted for understanding the fundamental properties of such collisionless edge plasma. By using a drift kinetic equation solver without the assumption of nested flux surfaces (the KEATS code), it is possible to conduct the investigation. In this paper, we report the simulation study of ion transport in the ergodic region, neglecting the effects of an electric field and neutrals. The simulation results are interpreted through the discussion based on statistical studies.

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