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Title: Global linear gyrokinetic simulation of energetic particle-driven instabilities in the LHD stellarator

Abstract

Energetic particles are inherent to toroidal fusion systems and can drive instabilities in the Alfvén frequency range, leading to decreased heating efficiency, high heat fluxes on plasma-facing components, and decreased ignition margin. The applicability of global gyrokinetic simulation methods to macroscopic instabilities has now been demonstrated and it is natural to extend these methods to 3D configurations such as stellarators, tokamaks with 3D coils and reversed field pinch helical states. This has been achieved by coupling the GTC global gyrokinetic PIC model to the VMEC equilibrium model, including 3D effects in the field solvers and particle push. Here, this paper demonstrates the application of this new capability to the linearized analysis of Alfvénic instabilities in the LHD stellarator. For normal shear iota profiles, toroidal Alfvén instabilities in the n = 1 and 2 toroidal mode families are unstable with frequencies in the 75 to 110 kHz range. Also, an LHD case with non-monotonic shear is considered, indicating reductions in growth rate for the same energetic particle drive. Finally, since 3D magnetic fields will be present to some extent in all fusion devices, the extension of gyrokinetic models to 3D configurations is an important step for the simulation of future fusionmore » systems.« less

Authors:
ORCiD logo [1];  [2];  [3];  [3]
  1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  2. Univ. of California, Irvine, CA (United States). Dept. of Physics and Astronomy; Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
  3. National Inst. for Fusion Science, Toki (Japan)
Publication Date:
Research Org.:
Oak Ridge National Laboratory, Oak Ridge Leadership Computing Facility (OLCF); Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org.:
USDOE Office of Science (SC); USDOE National Nuclear Security Administration (NNSA)
OSTI Identifier:
1366391
Alternate Identifier(s):
OSTI ID: 1497274
Report Number(s):
LLNL-JRNL-748842
Journal ID: ISSN 0029-5515; AT1030100; ERAT021
Grant/Contract Number:  
AC05-00OR22725; AC02-05CH11231; AC52-07NA27344
Resource Type:
Accepted Manuscript
Journal Name:
Nuclear Fusion
Additional Journal Information:
Journal Volume: 57; Journal Issue: 8; Journal ID: ISSN 0029-5515
Publisher:
IOP Science
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; stellarator; LHD; gyrokinetics; Alfven wave; energetic particles; fast ion instability linear

Citation Formats

Spong, Donald A., Holod, Ihor, Todo, Y., and Osakabe, M. Global linear gyrokinetic simulation of energetic particle-driven instabilities in the LHD stellarator. United States: N. p., 2017. Web. doi:10.1088/1741-4326/aa7601.
Spong, Donald A., Holod, Ihor, Todo, Y., & Osakabe, M. Global linear gyrokinetic simulation of energetic particle-driven instabilities in the LHD stellarator. United States. doi:10.1088/1741-4326/aa7601.
Spong, Donald A., Holod, Ihor, Todo, Y., and Osakabe, M. Fri . "Global linear gyrokinetic simulation of energetic particle-driven instabilities in the LHD stellarator". United States. doi:10.1088/1741-4326/aa7601. https://www.osti.gov/servlets/purl/1366391.
@article{osti_1366391,
title = {Global linear gyrokinetic simulation of energetic particle-driven instabilities in the LHD stellarator},
author = {Spong, Donald A. and Holod, Ihor and Todo, Y. and Osakabe, M.},
abstractNote = {Energetic particles are inherent to toroidal fusion systems and can drive instabilities in the Alfvén frequency range, leading to decreased heating efficiency, high heat fluxes on plasma-facing components, and decreased ignition margin. The applicability of global gyrokinetic simulation methods to macroscopic instabilities has now been demonstrated and it is natural to extend these methods to 3D configurations such as stellarators, tokamaks with 3D coils and reversed field pinch helical states. This has been achieved by coupling the GTC global gyrokinetic PIC model to the VMEC equilibrium model, including 3D effects in the field solvers and particle push. Here, this paper demonstrates the application of this new capability to the linearized analysis of Alfvénic instabilities in the LHD stellarator. For normal shear iota profiles, toroidal Alfvén instabilities in the n = 1 and 2 toroidal mode families are unstable with frequencies in the 75 to 110 kHz range. Also, an LHD case with non-monotonic shear is considered, indicating reductions in growth rate for the same energetic particle drive. Finally, since 3D magnetic fields will be present to some extent in all fusion devices, the extension of gyrokinetic models to 3D configurations is an important step for the simulation of future fusion systems.},
doi = {10.1088/1741-4326/aa7601},
journal = {Nuclear Fusion},
number = 8,
volume = 57,
place = {United States},
year = {2017},
month = {6}
}

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Figures / Tables:

Figure 1 Figure 1: (a) 3D magnetic field variation on outer LHD flux surface, (b) normal and nonmonotonic rotational transform profiles used in the simulations of this paper.

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