(EX/9-2) ELM Propagation and Fluctuations Characteristics in H- and L-mode SOL Plasmas on JT-60U

N. Asakura1), N. Ohno2), H. Kawashima1), H. Miyoshi3), G. Matsunaga1), N. Oyama1), S. Takamura3), Y. Uesugi4), M. Takechi1), T. Nakano1), H. Kubo1)
1) Japan Atomic Energy Agency, Naka, Japan
2) EcoTopia Science Institute, Nagoya Univ., Nagoya, Aichi, Japan
3) Graduate School of Engineering, Nagoya Univ. Nagoya, Aichi, Japan
4) Faculty of Engineering, Kanazawa University, 2-40-20 Kodatsuno, Ishikawa, Japan

Abstract.  Radial transport of the SOL plasma was recently studied in order to understand heat and particle loading to the first wall and the SOL formation mechanism. Fast propagation of the ELM plasma and fluctuation properties in H- and L-modes were determined both at high-field-side (HFS) and low-field-side (LFS) SOL using reciprocating Mach probes in JT-60U. Large and short (10-20 μs) peaks were found in ELM plasma flux (js) mostly at LFS SOL, which was enhanced after each ELM event (magnetic turbulence). Transport dynamics of the first large js peak was determined: it propagated to near the LFS first wall with the fast velocity of 1.3-2.5 km/s with large decay length of 9 cm. Statistical analysis of a probability distribution function (p.d.f.) was applied to describe intermittent (non-diffusion) transport in SOL plasma fluctuations. It was, for the first time, found that the positive bursty events appeared most frequently at LFS midplane distance from separatrix (Δr) 5 cm, and flat far SOL was formed in outer flux surfaces (Δr > 5 cm). Positive bursty events were seen in wide SOL radii (Δr < 7 cm) only at LFS midplane, where the “flow reversal” of the SOL plasma was observed. Influences of the radial transport of the convective blobby plasma on the SOL formation and the flow reversal were investigated.

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