Heat flux and plasma flow in the far scrape-off layer of the inboard poloidal field null configuration in QUEST

Takumi Onchi, H. Zushi, K. Mishra, Y. Mahira, K. Nagaoka, Kazuaki Hanada, Hiroshi Idei, Makoto Hasegawa, K. Nakamura, akihide fujisawa, Yoshihiko Nagashima, K. Matsuoka, S. Tashima, S. Banerjee, A. Kuzmin, S. Kawasaki, H. Nakashima, A. Higashijima, O. Watanabe

Research output: Contribution to journalArticle

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Abstract

Heat flux and plasma flow in the scrape-off layer (SOL) are examined for the inboard poloidal field null (IPN) configuration of the spherical tokamak QUEST. In the plasma current (Ip) ramp-up phase, high heat flux (>1 MW/m2) and supersonic flow (Mach number M > 1) are found to be present simultaneously in the far-SOL. The heat flux is generated by energetic electrons excursed from the last closed flux surface. Supersonic flows in the poloidal and toroidal directions are correlated with each other. In the quasi-steady state, sawtooth-like oscillation of Ip at 20 Hz is observed. Heat flux and subsonic plasma flow in the far-SOL are modified corresponding to the Ip-oscillation. The heat flow caused by motion of energetic electrons and the bulk-particle transport to the far-SOL is enhanced during the low-Ip phase. Modification of plasma flow in the far SOL occurs earlier than the Ip crash. The M-Ip curve has a limit-cycle characteristic with sawtooth-like oscillation. Such a core-SOL relationship indicates that the far-SOL flow plays an important role in sustaining the oscillation of Ip in the IPN configuration.

Original languageEnglish
Article number082513
JournalPhysics of Plasmas
Volume22
Issue number8
DOIs
Publication statusPublished - Aug 1 2015

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magnetohydrodynamic flow
heat flux
configurations
oscillations
supersonic flow
crashes
quasi-steady states
sustaining
plasma currents
ramps
heat transmission
Mach number
electrons
cycles
curves

All Science Journal Classification (ASJC) codes

  • Condensed Matter Physics

Cite this

Heat flux and plasma flow in the far scrape-off layer of the inboard poloidal field null configuration in QUEST. / Onchi, Takumi; Zushi, H.; Mishra, K.; Mahira, Y.; Nagaoka, K.; Hanada, Kazuaki; Idei, Hiroshi; Hasegawa, Makoto; Nakamura, K.; fujisawa, akihide; Nagashima, Yoshihiko; Matsuoka, K.; Tashima, S.; Banerjee, S.; Kuzmin, A.; Kawasaki, S.; Nakashima, H.; Higashijima, A.; Watanabe, O.

In: Physics of Plasmas, Vol. 22, No. 8, 082513, 01.08.2015.

Research output: Contribution to journalArticle

Onchi, T, Zushi, H, Mishra, K, Mahira, Y, Nagaoka, K, Hanada, K, Idei, H, Hasegawa, M, Nakamura, K, fujisawa, A, Nagashima, Y, Matsuoka, K, Tashima, S, Banerjee, S, Kuzmin, A, Kawasaki, S, Nakashima, H, Higashijima, A & Watanabe, O 2015, 'Heat flux and plasma flow in the far scrape-off layer of the inboard poloidal field null configuration in QUEST', Physics of Plasmas, vol. 22, no. 8, 082513. https://doi.org/10.1063/1.4928878
Onchi, Takumi ; Zushi, H. ; Mishra, K. ; Mahira, Y. ; Nagaoka, K. ; Hanada, Kazuaki ; Idei, Hiroshi ; Hasegawa, Makoto ; Nakamura, K. ; fujisawa, akihide ; Nagashima, Yoshihiko ; Matsuoka, K. ; Tashima, S. ; Banerjee, S. ; Kuzmin, A. ; Kawasaki, S. ; Nakashima, H. ; Higashijima, A. ; Watanabe, O. / Heat flux and plasma flow in the far scrape-off layer of the inboard poloidal field null configuration in QUEST. In: Physics of Plasmas. 2015 ; Vol. 22, No. 8.
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