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Title: Collisional enhancement of energetic particle Alfvénic resonance width in tokamaks

Abstract

The phase-space structure of resonances between fast ions and an Alfvénic mode and the associated modification of density profiles in tokamaks are studied as a function of particle collisions. Guiding-center simulations in a realistic tokamak equilibrium are employed to address the resonance broadening parametric dependencies with respect to changes in the pitch-angle scattering rate. The rate of collisional replenishment, along with resonance strength, given by the combination of eigenmode and resonance structures and equilibrium parameters, determines saturation amplitudes for a given damping rate. As seen from the distribution function flattening, collisions have an effect of broadening the resonances, while the absolute value of δf decreases with increasing collisionality. It is observed that the collisional broadening can be comparable to the collisionless resonance width due to the mode amplitude alone. The resonance broadening coefficients are compared with the existing theory based on analytically expected saturation levels, showing fair agreement. Furthermore the results can be useful in assisting reduced kinetic models, such as quasilinear models, when prescribing the effective resonance phase-space width, i.e., the mode-particle interaction platform, due to collisional or turbulent processes.

Authors:
ORCiD logo [1]; ORCiD logo [1]; ORCiD logo [1]; ORCiD logo [2]
  1. Princeton Univ., Princeton, NJ (United States). Princeton Plasma Physics Lab
  2. Max Planck Institute for Plasma Physics, Garching (Germany)
Publication Date:
Research Org.:
Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1503325
Alternate Identifier(s):
OSTI ID: 1501956
Grant/Contract Number:  
AC02-09CH11466
Resource Type:
Accepted Manuscript
Journal Name:
Physics of Plasmas
Additional Journal Information:
Journal Volume: 26; Journal Issue: 3; 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

White, R. B., Duarte, V. N., Gorelenkov, N. N., and Meng, G. Collisional enhancement of energetic particle Alfvénic resonance width in tokamaks. United States: N. p., 2019. Web. doi:10.1063/1.5088598.
White, R. B., Duarte, V. N., Gorelenkov, N. N., & Meng, G. Collisional enhancement of energetic particle Alfvénic resonance width in tokamaks. United States. doi:10.1063/1.5088598.
White, R. B., Duarte, V. N., Gorelenkov, N. N., and Meng, G. Wed . "Collisional enhancement of energetic particle Alfvénic resonance width in tokamaks". United States. doi:10.1063/1.5088598.
@article{osti_1503325,
title = {Collisional enhancement of energetic particle Alfvénic resonance width in tokamaks},
author = {White, R. B. and Duarte, V. N. and Gorelenkov, N. N. and Meng, G.},
abstractNote = {The phase-space structure of resonances between fast ions and an Alfvénic mode and the associated modification of density profiles in tokamaks are studied as a function of particle collisions. Guiding-center simulations in a realistic tokamak equilibrium are employed to address the resonance broadening parametric dependencies with respect to changes in the pitch-angle scattering rate. The rate of collisional replenishment, along with resonance strength, given by the combination of eigenmode and resonance structures and equilibrium parameters, determines saturation amplitudes for a given damping rate. As seen from the distribution function flattening, collisions have an effect of broadening the resonances, while the absolute value of δf decreases with increasing collisionality. It is observed that the collisional broadening can be comparable to the collisionless resonance width due to the mode amplitude alone. The resonance broadening coefficients are compared with the existing theory based on analytically expected saturation levels, showing fair agreement. Furthermore the results can be useful in assisting reduced kinetic models, such as quasilinear models, when prescribing the effective resonance phase-space width, i.e., the mode-particle interaction platform, due to collisional or turbulent processes.},
doi = {10.1063/1.5088598},
journal = {Physics of Plasmas},
number = 3,
volume = 26,
place = {United States},
year = {2019},
month = {3}
}

Journal Article:
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This content will become publicly available on March 20, 2020
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