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Production of internal transport barriers via self-generated mean flows in Alcator C-Mod

Title
Production of internal transport barriers via self-generated mean flows in Alcator C-Mod
Author
이정표
Keywords
Laboratory procedures; H mode; Internal transport barrier; Atmospheric physics; Plasma diagnostics; General physics; Plasma gyrokinetics; Geophysics; Ionospheric physics; Optics and optical physics
Issue Date
2012-04
Publisher
AMERICAN INSTITUTE OF PHYSICS
Citation
Physics of Plasmas, Vol.19, No.5 [2012], p056113-1 ~ 056113-7
Abstract
New results suggest that changes observed in the intrinsic toroidal rotation influence the internal transport barrier (ITB) formation in the Alcator C-Mod tokamak E. S. Marmar and Alcator C-Mod group, Fusion Sci. Technol. 51, 261 (2007). These arise when the resonance for ion cyclotron range of frequencies (ICRF) minority heating is positioned off-axis at or outside of the plasma half-radius. These ITBs form in a reactor relevant regime, without particle or momentum injection, with Ti ≈ Te, and with monotonic q profiles (qmin ≤ 1). C-Mod H-mode plasmas exhibit strong intrinsic co-current rotation that increases with increasing stored energy without external drive. When the resonance position is moved off-axis, the rotation decreases in the center of the plasma resulting in a radial toroidal rotation profile with a central well which deepens and moves farther off-axis when the ICRF resonance location reaches the plasma half-radius. This profile results in strong E × B shear (>1.5 × 105 rad/s) in the region where the ITB foot is observed. Gyrokinetic analyses indicate that this spontaneous shearing rate is comparable to the linear ion temperature gradient (ITG) growth rate at the ITB location and is sufficient to reduce the turbulent particle and energy transport. New and detailed measurement of the ion temperature demonstrates that the radial profile flattens as the ICRF resonance position moves off axis, decreasing the drive for the ITG the instability as well. These results are the first evidence that intrinsic rotation can affect confinement in ITB plasmas.
URI
http://aip.scitation.org/doi/10.1063/1.3694668https://repository.hanyang.ac.kr/handle/20.500.11754/70181
ISSN
1070-664X
DOI
10.1063/1.3694668
Appears in Collections:
COLLEGE OF ENGINEERING[S](공과대학) > NUCLEAR ENGINEERING(원자력공학과) > Articles
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