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Title: Effects of energetic particle phase space modifications by instabilities on integrated modeling

Abstract

Tokamak plasmas can feature a large population of energetic particles (EP) from neutral beam injection or fusion reactions. In turn, energetic particles can drive instabilities, which affect the driving EP population leading to a distortion of the original EP distribution function and of quantities that depend on it. The latter include, for example, neutral beam (NB) current drive and plasma heating through EP thermalization. Those effects must be taken into account to enable reliable and quantitative simulations of discharges for present devices as well as predictions for future burning plasmas. Reduced models for EP transport are emerging as an effective tool for long time-scale integrated simulations of tokamak plasmas, possibly including the effects of instabilities on EP dynamics. Available models differ in how EP distribution properties are modified by instabilities, e.g. in terms of gradients in real or phase space. It is therefore crucial to assess to what extent different assumptions in the transport models affect predicted quantities such as EP profile, energy distribution, NB driven current and energy/momentum transfer to the thermal populations. A newly developed kick model, which includes modifications of the EP distribution by instabilities in both real and velocity space, is used in this work tomore » investigate these issues. Coupled to TRANSP simulations, the kick model is used to analyze NB-heated NSTX and DIII-D discharges featuring unstable Alfvén eigenmodes (AEs). Results show that instabilities can strongly affect the EP distribution function, and modifications propagate to macroscopic quantities such as NB-driven current profile and NB power transferred to the thermal plasma species. Furthermore, those important aspects are only qualitatively captured by simpler fast ion transport models that are based on radial diffusion of energetic ions only.« less

Authors:
 [1];  [1];  [1];  [1];  [1]
  1. Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
Publication Date:
Research Org.:
Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); General Atomics, San Diego, CA (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Fusion Energy Sciences (FES) (SC-24)
Contributing Org.:
Princeton Plasma Physics Laboratory, Princeton NJ 08543 - USA
OSTI Identifier:
1346925
Alternate Identifier(s):
OSTI ID: 1267536; OSTI ID: 1347147; OSTI ID: 1371851
Grant/Contract Number:  
AC02-09CH11466; FC02-04ER54698
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Nuclear Fusion
Additional Journal Information:
Journal Volume: 56; Journal Issue: 11; Journal ID: ISSN 0029-5515
Publisher:
IOP Science
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY

Citation Formats

Podesta, M., Gorelenkova, M., Fredrickson, E. D., Gorelenkov, N. N., and White, R. B.. Effects of energetic particle phase space modifications by instabilities on integrated modeling. United States: N. p., 2016. Web. doi:10.1088/0029-5515/56/11/112005.
Podesta, M., Gorelenkova, M., Fredrickson, E. D., Gorelenkov, N. N., & White, R. B.. Effects of energetic particle phase space modifications by instabilities on integrated modeling. United States. doi:10.1088/0029-5515/56/11/112005.
Podesta, M., Gorelenkova, M., Fredrickson, E. D., Gorelenkov, N. N., and White, R. B.. Fri . "Effects of energetic particle phase space modifications by instabilities on integrated modeling". United States. doi:10.1088/0029-5515/56/11/112005. https://www.osti.gov/servlets/purl/1346925.
@article{osti_1346925,
title = {Effects of energetic particle phase space modifications by instabilities on integrated modeling},
author = {Podesta, M. and Gorelenkova, M. and Fredrickson, E. D. and Gorelenkov, N. N. and White, R. B.},
abstractNote = {Tokamak plasmas can feature a large population of energetic particles (EP) from neutral beam injection or fusion reactions. In turn, energetic particles can drive instabilities, which affect the driving EP population leading to a distortion of the original EP distribution function and of quantities that depend on it. The latter include, for example, neutral beam (NB) current drive and plasma heating through EP thermalization. Those effects must be taken into account to enable reliable and quantitative simulations of discharges for present devices as well as predictions for future burning plasmas. Reduced models for EP transport are emerging as an effective tool for long time-scale integrated simulations of tokamak plasmas, possibly including the effects of instabilities on EP dynamics. Available models differ in how EP distribution properties are modified by instabilities, e.g. in terms of gradients in real or phase space. It is therefore crucial to assess to what extent different assumptions in the transport models affect predicted quantities such as EP profile, energy distribution, NB driven current and energy/momentum transfer to the thermal populations. A newly developed kick model, which includes modifications of the EP distribution by instabilities in both real and velocity space, is used in this work to investigate these issues. Coupled to TRANSP simulations, the kick model is used to analyze NB-heated NSTX and DIII-D discharges featuring unstable Alfvén eigenmodes (AEs). Results show that instabilities can strongly affect the EP distribution function, and modifications propagate to macroscopic quantities such as NB-driven current profile and NB power transferred to the thermal plasma species. Furthermore, those important aspects are only qualitatively captured by simpler fast ion transport models that are based on radial diffusion of energetic ions only.},
doi = {10.1088/0029-5515/56/11/112005},
journal = {Nuclear Fusion},
number = 11,
volume = 56,
place = {United States},
year = {Fri Jul 22 00:00:00 EDT 2016},
month = {Fri Jul 22 00:00:00 EDT 2016}
}

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