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Title: Impurity transport, turbulence transitions and intrinsic rotation in Alcator C-Mod plasmas

Abstract

Linear and nonlinear gyrokinetic simulations are used to probe turbulent impurity transport in intrinsically rotating tokamak plasmas. For this simulation-based study, experimental input parameters are taken from a pair of ICRF heated Alcator C-Mod discharges exhibiting a change in the sign of the normalized toroidal rotation gradient at mid-radius (i.e. a change from hollow to peaked intrinsic rotation profiles). The simulations show that there is no change in the peaking of the calcium impurity between the plasmas with peaked and hollow rotation profiles, suggesting that the impurity transport and the shape of the rotation do not always change together. Furthermore, near mid-radius, r/a = 0.5 (normalized midplane minor radius), the linear and nonlinear gyrokinetic simulations exhibit no evidence of a transition from ion temperature gradient (ITG) to trapped electron mode dominance when the intrinsic rotation profile changes from peaked to hollow. Finally, extensive nonlinear sensitivity analysis is performed, and there is no change in the ITG critical gradient or in the stiffness of ion heat transport with the change in the intrinsic toroidal rotation profile shape, which suggests that the shape of the rotation profile is not dominated by the ITG onset in these cases.

Authors:
 [1];  [2];  [2];  [3];  [4];  [2]
  1. Oak Ridge Inst. for Science and Education (ORISE), Oak Ridge, TN (United States)
  2. Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States). Plasma Science and Fusion Center
  3. Univ. of California, San Diego, CA (United States)
  4. General Atomics, San Diego, CA (United States)
Publication Date:
Research Org.:
Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Fusion Energy Sciences (FES) (SC-24)
OSTI Identifier:
1557618
Grant/Contract Number:  
FC02-99ER54512
Resource Type:
Accepted Manuscript
Journal Name:
Plasma Physics and Controlled Fusion
Additional Journal Information:
Journal Volume: 56; Journal Issue: 12; Journal ID: ISSN 0741-3335
Publisher:
IOP Science
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY

Citation Formats

Howard, N. T., White, A. E., Greenwald, M., Holland, C., Candy, J., and Rice, J. E. Impurity transport, turbulence transitions and intrinsic rotation in Alcator C-Mod plasmas. United States: N. p., 2014. Web. doi:10.1088/0741-3335/56/12/124004.
Howard, N. T., White, A. E., Greenwald, M., Holland, C., Candy, J., & Rice, J. E. Impurity transport, turbulence transitions and intrinsic rotation in Alcator C-Mod plasmas. United States. doi:10.1088/0741-3335/56/12/124004.
Howard, N. T., White, A. E., Greenwald, M., Holland, C., Candy, J., and Rice, J. E. Fri . "Impurity transport, turbulence transitions and intrinsic rotation in Alcator C-Mod plasmas". United States. doi:10.1088/0741-3335/56/12/124004. https://www.osti.gov/servlets/purl/1557618.
@article{osti_1557618,
title = {Impurity transport, turbulence transitions and intrinsic rotation in Alcator C-Mod plasmas},
author = {Howard, N. T. and White, A. E. and Greenwald, M. and Holland, C. and Candy, J. and Rice, J. E.},
abstractNote = {Linear and nonlinear gyrokinetic simulations are used to probe turbulent impurity transport in intrinsically rotating tokamak plasmas. For this simulation-based study, experimental input parameters are taken from a pair of ICRF heated Alcator C-Mod discharges exhibiting a change in the sign of the normalized toroidal rotation gradient at mid-radius (i.e. a change from hollow to peaked intrinsic rotation profiles). The simulations show that there is no change in the peaking of the calcium impurity between the plasmas with peaked and hollow rotation profiles, suggesting that the impurity transport and the shape of the rotation do not always change together. Furthermore, near mid-radius, r/a = 0.5 (normalized midplane minor radius), the linear and nonlinear gyrokinetic simulations exhibit no evidence of a transition from ion temperature gradient (ITG) to trapped electron mode dominance when the intrinsic rotation profile changes from peaked to hollow. Finally, extensive nonlinear sensitivity analysis is performed, and there is no change in the ITG critical gradient or in the stiffness of ion heat transport with the change in the intrinsic toroidal rotation profile shape, which suggests that the shape of the rotation profile is not dominated by the ITG onset in these cases.},
doi = {10.1088/0741-3335/56/12/124004},
journal = {Plasma Physics and Controlled Fusion},
number = 12,
volume = 56,
place = {United States},
year = {2014},
month = {11}
}

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Works referenced in this record:

Spatially resolved high resolution x-ray spectroscopy for magnetically confined fusion plasmas (invited)
journal, October 2008

  • Ince-Cushman, A.; Rice, J. E.; Bitter, M.
  • Review of Scientific Instruments, Vol. 79, Issue 10, Article No. 10E302
  • DOI: 10.1063/1.2968707