Eigenmode characterizations of slab ion-temperature-gradient instabilities in various magnetic shear configurations
Comprehensive eigenmode characterizations of ion-temperature-gradient (ITG) instabilities in slab geometries with different magnetic shear profiles are investigated using an eigenvalue method. The results in the uniform magnetic shear configuration are verified via the Hamaguchi–Horton theory [S. Ha...
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doaj-37fee1ccdd7747b9bb6284c19d5b82202021-06-01T18:31:02ZengAIP Publishing LLCAIP Advances2158-32262021-05-01115055022055022-810.1063/5.0047990Eigenmode characterizations of slab ion-temperature-gradient instabilities in various magnetic shear configurationsGuangzhi Ren0Lai Wei1Fang Yu2Zheng-Xiong Wang3Jiquan Li4Key Laboratory of Materials Modification by Laser, Ion, and Electron Beams (Ministry of Education), School of Physics, Dalian University of Technology, Dalian 116024, ChinaKey Laboratory of Materials Modification by Laser, Ion, and Electron Beams (Ministry of Education), School of Physics, Dalian University of Technology, Dalian 116024, ChinaSchool of Mathematical Sciences, Dalian University of Technology, Dalian 116024, ChinaKey Laboratory of Materials Modification by Laser, Ion, and Electron Beams (Ministry of Education), School of Physics, Dalian University of Technology, Dalian 116024, ChinaSouthwestern Institute of Physics, Chengdu, Sichuan 610041, ChinaComprehensive eigenmode characterizations of ion-temperature-gradient (ITG) instabilities in slab geometries with different magnetic shear profiles are investigated using an eigenvalue method. The results in the uniform magnetic shear configuration are verified via the Hamaguchi–Horton theory [S. Hamaguchi and W. Horton, Phys. Fluids B 2, 1833 (1990)]. However, it is interestingly found that the linear growth rate and mode frequency change non-monotonically as the magnetic shear at the half simulation domain s(x < x0) changes continuously from the positive value to the negative value. There are multiple peaks in the dependence curve of the linear growth rate on s(x < x0) in the weak magnetic shear regime. The variation of magnetic shear, which can produce an additional potential well to excite instability, is identified to play an important role in the maximization of the growth rate of slab ITG modes. In the configuration with a moderate separation between two potential wells, multiple ITG modes with higher radial wave numbers l become unstable simultaneously. While |s(x < x0)| is weak compared to the local magnetic shear s(x = x0) at the center mode rational surface, asymmetric structures of low-order eigenmodes are obtained and high-order eigenmodes tend to be localized between two potential wells. Additionally, as the separation between two rational surfaces in the negative shear configuration further decreases, the high-order-l eigenmode would be stabilized. The mode structures of the low-order-l unstable eigenmode are present between two rational surfaces.http://dx.doi.org/10.1063/5.0047990 |
collection |
DOAJ |
language |
English |
format |
Article |
sources |
DOAJ |
author |
Guangzhi Ren Lai Wei Fang Yu Zheng-Xiong Wang Jiquan Li |
spellingShingle |
Guangzhi Ren Lai Wei Fang Yu Zheng-Xiong Wang Jiquan Li Eigenmode characterizations of slab ion-temperature-gradient instabilities in various magnetic shear configurations AIP Advances |
author_facet |
Guangzhi Ren Lai Wei Fang Yu Zheng-Xiong Wang Jiquan Li |
author_sort |
Guangzhi Ren |
title |
Eigenmode characterizations of slab ion-temperature-gradient instabilities in various magnetic shear configurations |
title_short |
Eigenmode characterizations of slab ion-temperature-gradient instabilities in various magnetic shear configurations |
title_full |
Eigenmode characterizations of slab ion-temperature-gradient instabilities in various magnetic shear configurations |
title_fullStr |
Eigenmode characterizations of slab ion-temperature-gradient instabilities in various magnetic shear configurations |
title_full_unstemmed |
Eigenmode characterizations of slab ion-temperature-gradient instabilities in various magnetic shear configurations |
title_sort |
eigenmode characterizations of slab ion-temperature-gradient instabilities in various magnetic shear configurations |
publisher |
AIP Publishing LLC |
series |
AIP Advances |
issn |
2158-3226 |
publishDate |
2021-05-01 |
description |
Comprehensive eigenmode characterizations of ion-temperature-gradient (ITG) instabilities in slab geometries with different magnetic shear profiles are investigated using an eigenvalue method. The results in the uniform magnetic shear configuration are verified via the Hamaguchi–Horton theory [S. Hamaguchi and W. Horton, Phys. Fluids B 2, 1833 (1990)]. However, it is interestingly found that the linear growth rate and mode frequency change non-monotonically as the magnetic shear at the half simulation domain s(x < x0) changes continuously from the positive value to the negative value. There are multiple peaks in the dependence curve of the linear growth rate on s(x < x0) in the weak magnetic shear regime. The variation of magnetic shear, which can produce an additional potential well to excite instability, is identified to play an important role in the maximization of the growth rate of slab ITG modes. In the configuration with a moderate separation between two potential wells, multiple ITG modes with higher radial wave numbers l become unstable simultaneously. While |s(x < x0)| is weak compared to the local magnetic shear s(x = x0) at the center mode rational surface, asymmetric structures of low-order eigenmodes are obtained and high-order eigenmodes tend to be localized between two potential wells. Additionally, as the separation between two rational surfaces in the negative shear configuration further decreases, the high-order-l eigenmode would be stabilized. The mode structures of the low-order-l unstable eigenmode are present between two rational surfaces. |
url |
http://dx.doi.org/10.1063/5.0047990 |
work_keys_str_mv |
AT guangzhiren eigenmodecharacterizationsofslabiontemperaturegradientinstabilitiesinvariousmagneticshearconfigurations AT laiwei eigenmodecharacterizationsofslabiontemperaturegradientinstabilitiesinvariousmagneticshearconfigurations AT fangyu eigenmodecharacterizationsofslabiontemperaturegradientinstabilitiesinvariousmagneticshearconfigurations AT zhengxiongwang eigenmodecharacterizationsofslabiontemperaturegradientinstabilitiesinvariousmagneticshearconfigurations AT jiquanli eigenmodecharacterizationsofslabiontemperaturegradientinstabilitiesinvariousmagneticshearconfigurations |
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