Density sensitivity of intrinsic rotation profiles in ion cyclotron range of frequency-heated L-mode plasmas
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White_Density sensitivity.pdf
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Author(s)
Reinke, Matthew Logan
Rice, John E.
White, Anne E.
Greenwald, Martin J.
Howard, Nathaniel Thomas
Ennever, Paul Chappell
Gao, Chi
Hubbard, Amanda E
Hughes Jr, Jerry
Date Issued
January 2013
Journal
Plasma Physics and Controlled Fusion
Publisher
IOP Publishing
Citation
Reinke, M L, J E Rice, A E White, M Greenwald, N T Howard, P Ennever, C Gao, A E Hubbard, and J W Hughes. “Density sensitivity of intrinsic rotation profiles in ion cyclotron range of frequency-heated L-mode plasmas.” Plasma Physics and Controlled Fusion 55, no. 1 (January 1, 2013): 012001.
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Author's final manuscript
Abstract
The physical mechanisms that cause tokamak plasmas to rotate toroidally without external momentum input are of considerable interest to the plasma physics community. This paper documents a substantial change in both the magnitude of the core-rotation frequency, −1 < ω(r/a = 0) < +10 kHz, and the sign of rotation shear at mid-radius, u' = −R[superscript 2] dω/dr/v[subscript th,i], which varies in the range −0.6 < u' < +0.8 in response to very small changes in the electron density. In 0.8 MA, 5.4 T Alcator C-Mod L-mode plasmas using 1.2 MW of on-axis ion-cyclotron resonance heating, plasmas with line-averaged densities in the range 1.0 < [bar over n][subscript e] < 1.2 X 10[superscript 20] m[superscript -3] exhibit a transition from a peaked intrinsic rotation profile to one that is hollow. Gradient scale lengths of the temperature and density profiles, the drive for plasma turbulence thought to play a role in intrinsic rotation, are indistinguishable within experimental uncertainties between the plasmas, and linear stability analysis using GYRO shows the plasmas to be in the ion temperature gradient-dominated turbulence regime. The impact of changes in the rotation profile in response to minor changes under target plasma conditions is discussed in relation to established analysis techniques and cross-machine rotation scaling studies, with comparisons made with existing ASDEX-Upgrade work on intrinsic rotation shear.
MIT Department
Massachusetts Institute of Technology. Department of Nuclear Science and Engineering
Massachusetts Institute of Technology. Department of Physics
Massachusetts Institute of Technology. Plasma Science and Fusion Center
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DOI of Published Version
https://doi.org/10.1088/0741-3335/55/1/012001
