Validation of nonlinear gyrokinetic simulations of L- and I-mode plasmas on Alcator C-Mod

Creely, A. J.; Howard, N. T.; Rodriguez-Fernandez, P.; Cao, N.; Hubbard, A. E.; Hughes, J. W.; Rice, J. E.; White, A. E.; Candy, J.; Staebler, G. M.; Conway, G. D.; Freethy, S. J.; Sung, C.

doi:10.7910/DVN/XTUKGA

Title: Validation of nonlinear gyrokinetic simulations of L- and I-mode plasmas on Alcator C-Mod

Abstract

New validation of global, nonlinear, ion-scale gyrokinetic simulations (GYRO) is carried out for L- and I-mode plasmas on Alcator C-Mod, utilizing heat fluxes, profile stiffness, and temperature fluctuations. Previous work at C-Mod found that ITG/TEM-scale GYRO simulations can match both electron and ion heat fluxes within error bars in I-mode [White PoP 2015], suggesting that multi-scale (cross-scale coupling) effects [Howard PoP 2016] may be less important in I-mode than in L-mode. New results presented here, however, show that global, nonlinear, ion-scale GYRO simulations are able to match the experimental ion heat flux, but underpredict electron heat flux (at most radii), electron temperature fluctuations, and perturbative thermal diffusivity in both L- and I-mode. Linear addition of electron heat flux from electron scale runs does not resolve this discrepancy. These results indicate that single-scale simulations do not sufficiently describe the I-mode core transport, and that multi-scale (coupled electron- and ion-scale) transport models are needed. A preliminary investigation with multi-scale TGLF, however, was unable to resolve the discrepancy between ion-scale GYRO and experimental electron heat fluxes and perturbative diffusivity, motivating further work with multi-scale GYRO simulations and a more comprehensive study with multi-scale TGLF.

Authors:: Creely, A. J.; Howard, N. T.; Rodriguez-Fernandez, P.; Cao, N.; Hubbard, A. E.; Hughes, J. W.; Rice, J. E.; White, A. E.; Candy, J.; Staebler, G. M.; Conway, G. D.; Freethy, S. J.; Sung, C.

Publication Date:: 2018-10-16

DOE Contract Number:: SC0006419; FC02-99ER54512; AC02-05CH11231

Research Org.:: Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States). Plasma Science and Fusion Center

Sponsoring Org.:: USDOE Office of Science (SC), Fusion Energy Sciences (FES)

Subject:: 70 PLASMA PHYSICS AND FUSION TECHNOLOGY

OSTI Identifier:: 1880090

DOI:: https://doi.org/10.7910/DVN/XTUKGA

Citation Formats


                    Creely, A. J., Howard, N. T., Rodriguez-Fernandez, P., Cao, N., Hubbard, A. E., Hughes, J. W., Rice, J. E., White, A. E., Candy, J., Staebler, G. M., Conway, G. D., Freethy, S. J., and Sung, C. Validation of nonlinear gyrokinetic simulations of L- and I-mode plasmas on Alcator C-Mod.  United States: N. p., 2018. 
        Web.  doi:10.7910/DVN/XTUKGA.

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                    Creely, A. J., Howard, N. T., Rodriguez-Fernandez, P., Cao, N., Hubbard, A. E., Hughes, J. W., Rice, J. E., White, A. E., Candy, J., Staebler, G. M., Conway, G. D., Freethy, S. J., & Sung, C. Validation of nonlinear gyrokinetic simulations of L- and I-mode plasmas on Alcator C-Mod.  United States.  doi:https://doi.org/10.7910/DVN/XTUKGA

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                    Creely, A. J., Howard, N. T., Rodriguez-Fernandez, P., Cao, N., Hubbard, A. E., Hughes, J. W., Rice, J. E., White, A. E., Candy, J., Staebler, G. M., Conway, G. D., Freethy, S. J., and Sung, C. 2018.  
"Validation of nonlinear gyrokinetic simulations of L- and I-mode plasmas on Alcator C-Mod".  United States.  doi:https://doi.org/10.7910/DVN/XTUKGA.  https://www.osti.gov/servlets/purl/1880090. Pub date:Tue Oct 16 00:00:00 EDT 2018

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@article{osti_1880090,

  title        = {Validation of nonlinear gyrokinetic simulations of L- and I-mode plasmas on Alcator C-Mod},

  author       = {Creely, A. J. and Howard, N. T. and Rodriguez-Fernandez, P. and Cao, N. and Hubbard, A. E. and Hughes, J. W. and Rice, J. E. and White, A. E. and Candy, J. and Staebler, G. M. and Conway, G. D. and Freethy, S. J. and Sung, C.},

  abstractNote = {New validation of global, nonlinear, ion-scale gyrokinetic simulations (GYRO) is carried out for L- and I-mode plasmas on Alcator C-Mod, utilizing heat fluxes, profile stiffness, and temperature fluctuations. Previous work at C-Mod found that ITG/TEM-scale GYRO simulations can match both electron and ion heat fluxes within error bars in I-mode [White PoP 2015], suggesting that multi-scale (cross-scale coupling) effects [Howard PoP 2016] may be less important in I-mode than in L-mode. New results presented here, however, show that global, nonlinear, ion-scale GYRO simulations are able to match the experimental ion heat flux, but underpredict electron heat flux (at most radii), electron temperature fluctuations, and perturbative thermal diffusivity in both L- and I-mode. Linear addition of electron heat flux from electron scale runs does not resolve this discrepancy. These results indicate that single-scale simulations do not sufficiently describe the I-mode core transport, and that multi-scale (coupled electron- and ion-scale) transport models are needed. A preliminary investigation with multi-scale TGLF, however, was unable to resolve the discrepancy between ion-scale GYRO and experimental electron heat fluxes and perturbative diffusivity, motivating further work with multi-scale GYRO simulations and a more comprehensive study with multi-scale TGLF.},

  doi          = {10.7910/DVN/XTUKGA},

  journal      = {},

  number       = ,

  volume       = ,

  place        = {United States},

  year         = {2018},

  month        = {10}

}

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