The theory of early nonlinear stage of m=1 instability with locally flattened q-profile

In this paper, we analyze the modification of fast particles on the nonlinear radial displacement of m = 1 internal kink mode with a shoulder-like equilibrium current theoretically. Using the matching method on the solutions of the outer and inner regions, we derive the analytical form of nonlinear...

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Main Authors: Kai-Qi Cao, Xian-Qu Wang
Format: Article
Language:English
Published: AIP Publishing LLC 2018-09-01
Series:Matter and Radiation at Extremes
Online Access:http://dx.doi.org/10.1016/j.mre.2018.04.002
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author Kai-Qi Cao
Xian-Qu Wang
author_facet Kai-Qi Cao
Xian-Qu Wang
author_sort Kai-Qi Cao
collection DOAJ
description In this paper, we analyze the modification of fast particles on the nonlinear radial displacement of m = 1 internal kink mode with a shoulder-like equilibrium current theoretically. Using the matching method on the solutions of the outer and inner regions, we derive the analytical form of nonlinear radial displacement in the limit of q' = q" = 0, which is valid to the cases of weak shear due to a slight flattening of the q(r) profile around q = 1. We have taken into consideration the effects of the circulating and trapped fast particles on the nonlinear state of the mode. It is found that a fast particle can modify the nonlinear saturation level by the change of potential energy, depending on the fast particle properties. By the matching of linear dispersion relation to early nonlinear result, we also obtain the relations of radial displacement to the mode frequency and linear growth rate, and discuss the scaling for different stabilities of the MHD modes.
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spelling doaj.art-a24ea61f94f8415db70ef5d8088f73c12022-12-22T01:12:38ZengAIP Publishing LLCMatter and Radiation at Extremes2468-080X2018-09-013524324710.1016/j.mre.2018.04.002002805JCPThe theory of early nonlinear stage of m=1 instability with locally flattened q-profileKai-Qi Cao0Xian-Qu Wang1Institute of Fusion Science, School of Physical Science and Technology, Southwest Jiaotong University, Chengdu, Sichuan 610031, ChinaInstitute of Fusion Science, School of Physical Science and Technology, Southwest Jiaotong University, Chengdu, Sichuan 610031, ChinaIn this paper, we analyze the modification of fast particles on the nonlinear radial displacement of m = 1 internal kink mode with a shoulder-like equilibrium current theoretically. Using the matching method on the solutions of the outer and inner regions, we derive the analytical form of nonlinear radial displacement in the limit of q' = q" = 0, which is valid to the cases of weak shear due to a slight flattening of the q(r) profile around q = 1. We have taken into consideration the effects of the circulating and trapped fast particles on the nonlinear state of the mode. It is found that a fast particle can modify the nonlinear saturation level by the change of potential energy, depending on the fast particle properties. By the matching of linear dispersion relation to early nonlinear result, we also obtain the relations of radial displacement to the mode frequency and linear growth rate, and discuss the scaling for different stabilities of the MHD modes.http://dx.doi.org/10.1016/j.mre.2018.04.002
spellingShingle Kai-Qi Cao
Xian-Qu Wang
The theory of early nonlinear stage of m=1 instability with locally flattened q-profile
Matter and Radiation at Extremes
title The theory of early nonlinear stage of m=1 instability with locally flattened q-profile
title_full The theory of early nonlinear stage of m=1 instability with locally flattened q-profile
title_fullStr The theory of early nonlinear stage of m=1 instability with locally flattened q-profile
title_full_unstemmed The theory of early nonlinear stage of m=1 instability with locally flattened q-profile
title_short The theory of early nonlinear stage of m=1 instability with locally flattened q-profile
title_sort theory of early nonlinear stage of m 1 instability with locally flattened q profile
url http://dx.doi.org/10.1016/j.mre.2018.04.002
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