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Title: Improved kinetic neoclassical transport calculation for a low-collisionality QH-mode pedestal

Abstract

The role of neoclassical, anomalous and neutral transport to the overall H-mode pedestal and scrape-off layer (SOL) structure in an ELM-free QH-mode discharge on DIII-D is explored using XGC0, a 5D full-f multi-species particle-in-cell drift-kinetic solver with self-consistent neutral recycling and sheath potentials. The work in this paper builds on previous work aimed at achieving quantitative agreement between the flux-driven simulation and the experimental electron density, impurity density and orthogonal measurements of impurity temperature and flow profiles. Improved quantitative agreement is achieved by performing the calculations with a more realistic electron mass, larger neutral density and including finite-Larmor-radius corrections self-consistently in the drift-kinetic motion of the particles. Consequently, the simulations provide stronger evidence that the radial electric field (Er) in the pedestal is primarily established by the required balance between the loss of high-energy tail main ions against a pinch of colder main ions and impurities. The kinetic loss of a small population of ions carrying a large proportion of energy and momentum leads to a separation of the particle and energy transport rates and introduces a source of intrinsic edge torque. Ion orbit loss and finite orbit width effects drive the energy distributions away from Maxwellian, and describe themore » anisotropy, poloidal asymmetry and local minimum near the separatrix observed in the Ti profile.« less

Authors:
 [1];  [2];  [1];  [2]; ORCiD logo [1];  [2]; ORCiD logo [1]
  1. Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
  2. General Atomics, San Diego, CA (United States)
Publication Date:
Research Org.:
Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); General Atomics, San Diego, CA (United States); U.S. Dept. of Energy
Sponsoring Org.:
USDOE Office of Science (SC), Fusion Energy Sciences (FES) (SC-24)
Contributing Org.:
Princeton Plasma Physics Laboratory, P.O. Box 451, Princeton, NJ 08543, USA
OSTI Identifier:
1308447
Alternate Identifier(s):
OSTI ID: 1263685; OSTI ID: 1371847; OSTI ID: 1572197
Grant/Contract Number:  
AC02-09CH11466; FC02-04ER54698; FG02-07ER54917; AC05-00OR22725
Resource Type:
Accepted Manuscript
Journal Name:
Plasma Physics and Controlled Fusion
Additional Journal Information:
Journal Volume: 58; Journal Issue: 8; Journal ID: ISSN 0741-3335
Publisher:
IOP Science
Country of Publication:
United States
Language:
English
Subject:
74 ATOMIC AND MOLECULAR PHYSICS; tokamak; pedestal; electric field; transport; kinetic neoclassical; ion orbit loss; 70 PLASMA PHYSICS AND FUSION TECHNOLOGY; tokamak, pedestal, electric field, transport, kinetic neoclassical, ion orbit loss

Citation Formats

Battaglia, D. J., Burrell, K. H., Chang, C. S., deGrassie, J. S., Grierson, B. A., Groebner, R. J., and Hager, R. Improved kinetic neoclassical transport calculation for a low-collisionality QH-mode pedestal. United States: N. p., 2016. Web. doi:10.1088/0741-3335/58/8/085009.
Battaglia, D. J., Burrell, K. H., Chang, C. S., deGrassie, J. S., Grierson, B. A., Groebner, R. J., & Hager, R. Improved kinetic neoclassical transport calculation for a low-collisionality QH-mode pedestal. United States. doi:10.1088/0741-3335/58/8/085009.
Battaglia, D. J., Burrell, K. H., Chang, C. S., deGrassie, J. S., Grierson, B. A., Groebner, R. J., and Hager, R. Fri . "Improved kinetic neoclassical transport calculation for a low-collisionality QH-mode pedestal". United States. doi:10.1088/0741-3335/58/8/085009. https://www.osti.gov/servlets/purl/1308447.
@article{osti_1308447,
title = {Improved kinetic neoclassical transport calculation for a low-collisionality QH-mode pedestal},
author = {Battaglia, D. J. and Burrell, K. H. and Chang, C. S. and deGrassie, J. S. and Grierson, B. A. and Groebner, R. J. and Hager, R.},
abstractNote = {The role of neoclassical, anomalous and neutral transport to the overall H-mode pedestal and scrape-off layer (SOL) structure in an ELM-free QH-mode discharge on DIII-D is explored using XGC0, a 5D full-f multi-species particle-in-cell drift-kinetic solver with self-consistent neutral recycling and sheath potentials. The work in this paper builds on previous work aimed at achieving quantitative agreement between the flux-driven simulation and the experimental electron density, impurity density and orthogonal measurements of impurity temperature and flow profiles. Improved quantitative agreement is achieved by performing the calculations with a more realistic electron mass, larger neutral density and including finite-Larmor-radius corrections self-consistently in the drift-kinetic motion of the particles. Consequently, the simulations provide stronger evidence that the radial electric field (Er) in the pedestal is primarily established by the required balance between the loss of high-energy tail main ions against a pinch of colder main ions and impurities. The kinetic loss of a small population of ions carrying a large proportion of energy and momentum leads to a separation of the particle and energy transport rates and introduces a source of intrinsic edge torque. Ion orbit loss and finite orbit width effects drive the energy distributions away from Maxwellian, and describe the anisotropy, poloidal asymmetry and local minimum near the separatrix observed in the Ti profile.},
doi = {10.1088/0741-3335/58/8/085009},
journal = {Plasma Physics and Controlled Fusion},
number = 8,
volume = 58,
place = {United States},
year = {2016},
month = {7}
}

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