Core impurity transport in Alcator C-Mod L-, I- and H-mode plasmas
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D Whyte 14ja025_full.pdf
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Author(s)
Reinke, M.L.
Delgado-Aparicio, L.
Scott, S.D.
Rice, John E
Gao, Chi
Howard, Nathaniel Thomas
Chilenski, Mark Alan
Granetz, Robert S
Greenwald, Martin J
Hubbard, Amanda E
Date Issued
February 2015
Journal
Nuclear Fusion
Publisher
IOP Publishing
Citation
Rice, J.E. et al. “Core Impurity Transport in Alcator C-Mod L-, I- and H-Mode Plasmas.” Nuclear Fusion 55.3 (2015): 033014.
Version
Original manuscript
Abstract
Core impurity transport has been investigated for a variety of confinement regimes in Alcator C-Mod plasmas from x-ray emission following injection of medium and high Z materials. In ohmic L-mode discharges, impurity transport is anomalous (D[subscript eff] ≫ D[subscript nc]) and changes very little across the LOC/SOC boundary. In ion cyclotron range of frequencies (ICRF) heated L-mode plasmas, the core impurity confinement time decreases with increasing ICRF input power (and subsequent increasing electron temperature) and increases with plasma current. Nearly identical impurity confinement characteristics are observed in I-mode plasmas. In enhanced D[subscript α] H-mode discharges the core impurity confinement times are much longer. There is a strong connection between core impurity confinement time and the edge density gradient across all confinement regimes studied here. Deduced central impurity density profiles in stationary plasmas are generally flat, in spite of large amplitude sawtooth oscillations, and there is little evidence of impurity convection inside of r/a = 0.3 when averaged over sawteeth.
MIT Department
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/10.1088/0029-5515/55/3/033014
