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Title: Excitation of low frequency Alfven eigenmodes in toroidal plasmas

Abstract

Global gyrokinetic simulations find that realistic density gradients of energetic particles can simultaneously excite low frequency Alfven eigenmodes in toroidal geometry, beta-induced Alfven-acoustic eigenmode (BAAE) and beta-induced Alfven eigenmode (BAE), with similar radial mode widths and comparable linear growth rates even though damping rate of BAAE is much larger than BAE in the absence of energetic particles. This surprising result is attributed to non-perturbative effects of energetic particles that modify ideal BAAE mode polarizations and nonlocal geometry effects that invalidate radially local dispersion relation. Dominant mode changes from BAAE in a larger tokamak to BAE in a smaller tokamak due to the dependence of wave-particle resonance condition on the tokamak size.

Authors:
 [1];  [2];  [3]; ORCiD logo [4]
  1. Peking Univ., Beijing (China). Fusion Simulation Center; Univ. of California, Irvine, CA (United States). Dept. of Physics and Astronomy
  2. Univ. of California, Irvine, CA (United States). Dept. of Physics and Astronomy
  3. Peking Univ., Beijing (China). Fusion Simulation Center
  4. Univ. of California, Irvine, CA (United States). Dept. of Physics and Astronomy; Chinese Academy of Sciences (CAS), Beijing (China). Inst. of Physics
Publication Date:
Research Org.:
Oak Ridge National Laboratory, Oak Ridge Leadership Computing Facility (OLCF); Lawrence Berkeley National Laboratory-National Energy Research Scientific Computing Center
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
1523623
DOE Contract Number:  
AC02-05CH11231; AC05-00OR22725
Resource Type:
Journal Article
Journal Name:
Nuclear Fusion
Additional Journal Information:
Journal Volume: 57; Journal Issue: 11; Journal ID: ISSN 0029-5515
Country of Publication:
United States
Language:
English

Citation Formats

Liu, Yaqi, Lin, Zhihong, Zhang, Huasen, and Zhang, Wenlu. Excitation of low frequency Alfven eigenmodes in toroidal plasmas. United States: N. p., 2017. Web. doi:10.1088/1741-4326/aa7d14.
Liu, Yaqi, Lin, Zhihong, Zhang, Huasen, & Zhang, Wenlu. Excitation of low frequency Alfven eigenmodes in toroidal plasmas. United States. doi:10.1088/1741-4326/aa7d14.
Liu, Yaqi, Lin, Zhihong, Zhang, Huasen, and Zhang, Wenlu. Fri . "Excitation of low frequency Alfven eigenmodes in toroidal plasmas". United States. doi:10.1088/1741-4326/aa7d14.
@article{osti_1523623,
title = {Excitation of low frequency Alfven eigenmodes in toroidal plasmas},
author = {Liu, Yaqi and Lin, Zhihong and Zhang, Huasen and Zhang, Wenlu},
abstractNote = {Global gyrokinetic simulations find that realistic density gradients of energetic particles can simultaneously excite low frequency Alfven eigenmodes in toroidal geometry, beta-induced Alfven-acoustic eigenmode (BAAE) and beta-induced Alfven eigenmode (BAE), with similar radial mode widths and comparable linear growth rates even though damping rate of BAAE is much larger than BAE in the absence of energetic particles. This surprising result is attributed to non-perturbative effects of energetic particles that modify ideal BAAE mode polarizations and nonlocal geometry effects that invalidate radially local dispersion relation. Dominant mode changes from BAAE in a larger tokamak to BAE in a smaller tokamak due to the dependence of wave-particle resonance condition on the tokamak size.},
doi = {10.1088/1741-4326/aa7d14},
journal = {Nuclear Fusion},
issn = {0029-5515},
number = 11,
volume = 57,
place = {United States},
year = {2017},
month = {7}
}

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