Transport and turbulence studies in the linear ohmic confinement regime in Alcator C-Mod
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porkolab 4.pdf
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Author(s)
Candy, J.
Staebler, G. M.
Waltz, R. E.
Porkolab, Miklos
Ennever, Paul Chappell
Fiore, Catherine L.
Greenwald, Martin J.
Hubbard, Amanda E.
Dorris, James R.
Ma, Y.
Date Issued
November 2012
Journal
Plasma Physics and Controlled Fusion
Publisher
IOP Publishing
Citation
Porkolab, M, J Dorris, P Ennever, C Fiore, M Greenwald, A Hubbard, Y Ma, et al. “Transport and turbulence studies in the linear ohmic confinement regime in Alcator C-Mod.” Plasma Physics and Controlled Fusion 54, no. 12 (December 1, 2012): 124029.
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Author's final manuscript
Abstract
Transport in ohmically heated plasmas in Alcator C-Mod was studied in both the linear (LOC) and saturated (SOC) ohmic L-mode confinement regimes and the importance of turbulent transport in the region r/a = 0.5–0.8 was established. After an extensive analysis with TGLF and GYRO, it is found that using an effective impurity ion species with Z[subscript i] = 8, and moderately high Z[subscript eff] (2.0–5.6), in the LOC regime electron transport becomes dominant due to TEM turbulence. The key ingredient in the present results is the observation that dilution of the main ion species (deuterium) by impurity species of moderate charge state reduces dominant ITG turbulence, in contrast to the SOC regime with little, if any dilution. The turbulent spectrum measured with the phase contrast imaging (PCI) diagnostic is in qualitative agreement with predictions of a synthetic PCI diagnostic adopted to Global GYRO. The toroidal rotation in the low-density LOC regime is in the co-current direction but as the density is raised in the SOC regime the rotation reverses to the counter current drive direction. The impurity content of the plasma was measured recently and an effective Z[subscript i] of 9 was deduced.
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/10.1088/0741-3335/54/12/124029
