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Title: Multispecies density peaking in gyrokinetic turbulence simulations of low collisionality Alcator C-Mod plasmas

Abstract

Peaked density profiles in low-collisionality AUG and JET H-mode plasmas are probably caused by a turbulently driven particle pinch, and Alcator C-Mod experiments confirmed that collisionality is a critical parameter. Density peaking in reactors may produce a number of important effects, some beneficial, such as enhanced fusion power and transport of fuel ions from the edge to the core, while others are undesirable, such as lower beta limits, reduced radiation from the plasma edge, and consequently higher divertor heat loads. Fundamental understanding of the pinch will allow planning to optimize these impacts. We postulate that density peaking is predicted by nonlinear gyrokinetic turbulence simulations based on measured profile data from low collisionality H-mode plasma in Alcator C-Mod. Multiple ion species are included to determine whether hydrogenic density peaking has an isotope dependence or is influenced by typical levels of low-Z impurities, and whether impurity density peaking depends on the species. We determine that the deuterium density profile is slightly more peaked than that of hydrogen, and that experimentally relevant levels of boron have no appreciable effect on hydrogenic density peaking. The ratio of density at r/a = 0.44 to that at r/a = 0.74 is 1.2 for the majority Dmore » and minority H ions (and for electrons), and increases with impurity Z: 1.1 for helium, 1.15 for boron, 1.3 for neon, 1.4 for argon, and 1.5 for molybdenum. The ion temperature profile is varied to match better the predicted heat flux with the experimental transport analysis, but the resulting factor of two change in heat transport has only a weak effect on the predicted density peaking.« less

Authors:
ORCiD logo [1];  [1];  [1];  [1]; ORCiD logo [2];  [2]; ORCiD logo [2];  [2];  [3];  [4];  [5];  [6]; ORCiD logo [6]
  1. Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
  2. Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)
  3. Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States); Univ. of York (United Kingdom)
  4. Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States); National Science Foundation (NSF), Arlington, VA (United States)
  5. Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States); ITER Organization, St. Paul Lez Durance (France)
  6. 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:
1548289
Alternate Identifier(s):
OSTI ID: 1228197
Grant/Contract Number:  
FC02-99ER54512; AC02-09CH11466; FG02-95ER54309
Resource Type:
Accepted Manuscript
Journal Name:
Physics of Plasmas
Additional Journal Information:
Journal Volume: 22; Journal Issue: 6; Journal ID: ISSN 1070-664X
Publisher:
American Institute of Physics (AIP)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY

Citation Formats

Mikkelsen, D. R., Bitter, M., Delgado-Aparicio, L., Hill, K. W., Greenwald, M., Howard, N. T., Hughes, J. W., Rice, J. E., Reinke, M. L., Podpaly, Y., Ma, Y., Candy, J., and Waltz, R. E. Multispecies density peaking in gyrokinetic turbulence simulations of low collisionality Alcator C-Mod plasmas. United States: N. p., 2015. Web. doi:10.1063/1.4922069.
Mikkelsen, D. R., Bitter, M., Delgado-Aparicio, L., Hill, K. W., Greenwald, M., Howard, N. T., Hughes, J. W., Rice, J. E., Reinke, M. L., Podpaly, Y., Ma, Y., Candy, J., & Waltz, R. E. Multispecies density peaking in gyrokinetic turbulence simulations of low collisionality Alcator C-Mod plasmas. United States. doi:10.1063/1.4922069.
Mikkelsen, D. R., Bitter, M., Delgado-Aparicio, L., Hill, K. W., Greenwald, M., Howard, N. T., Hughes, J. W., Rice, J. E., Reinke, M. L., Podpaly, Y., Ma, Y., Candy, J., and Waltz, R. E. Thu . "Multispecies density peaking in gyrokinetic turbulence simulations of low collisionality Alcator C-Mod plasmas". United States. doi:10.1063/1.4922069. https://www.osti.gov/servlets/purl/1548289.
@article{osti_1548289,
title = {Multispecies density peaking in gyrokinetic turbulence simulations of low collisionality Alcator C-Mod plasmas},
author = {Mikkelsen, D. R. and Bitter, M. and Delgado-Aparicio, L. and Hill, K. W. and Greenwald, M. and Howard, N. T. and Hughes, J. W. and Rice, J. E. and Reinke, M. L. and Podpaly, Y. and Ma, Y. and Candy, J. and Waltz, R. E.},
abstractNote = {Peaked density profiles in low-collisionality AUG and JET H-mode plasmas are probably caused by a turbulently driven particle pinch, and Alcator C-Mod experiments confirmed that collisionality is a critical parameter. Density peaking in reactors may produce a number of important effects, some beneficial, such as enhanced fusion power and transport of fuel ions from the edge to the core, while others are undesirable, such as lower beta limits, reduced radiation from the plasma edge, and consequently higher divertor heat loads. Fundamental understanding of the pinch will allow planning to optimize these impacts. We postulate that density peaking is predicted by nonlinear gyrokinetic turbulence simulations based on measured profile data from low collisionality H-mode plasma in Alcator C-Mod. Multiple ion species are included to determine whether hydrogenic density peaking has an isotope dependence or is influenced by typical levels of low-Z impurities, and whether impurity density peaking depends on the species. We determine that the deuterium density profile is slightly more peaked than that of hydrogen, and that experimentally relevant levels of boron have no appreciable effect on hydrogenic density peaking. The ratio of density at r/a = 0.44 to that at r/a = 0.74 is 1.2 for the majority D and minority H ions (and for electrons), and increases with impurity Z: 1.1 for helium, 1.15 for boron, 1.3 for neon, 1.4 for argon, and 1.5 for molybdenum. The ion temperature profile is varied to match better the predicted heat flux with the experimental transport analysis, but the resulting factor of two change in heat transport has only a weak effect on the predicted density peaking.},
doi = {10.1063/1.4922069},
journal = {Physics of Plasmas},
number = 6,
volume = 22,
place = {United States},
year = {2015},
month = {6}
}

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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