https://doi.org/10.1140/epjp/s13360-023-04198-5
Regular Article
Nonlinear simulations of energetic particle modes in tokamak plasmas with reversed magnetic shear
Institute of Fusion Science, School of Physical Science and Technology, Southwest Jiaotong University, 610031, Chengdu, China
Received:
12
December
2022
Accepted:
16
June
2023
Published online:
23
June
2023
Effects of energetic particles (EPs) on m/n = 3/1 magnetohydrodynamic (MHD) instabilities have been investigated via hybrid simulations for reversed magnetic shear configurations. The simulation results shown that a global instability, energetic particle modes (EPMs), can be excited by the strong energetic particle drive with the frequency lying into the Alfvén continuum. In the linear growth stage, EPs not only induce radial broadening of mode structures but also enhance toroidal mode coupling when EP beta is large enough. In the nonlinear saturation stage, the good flux surfaces are still kept over the entire plasma area in a long time evolution of EPMs. To clarify nonlinear saturation of the mode, effects of the energetic particle beta values, the width of the particle distribution, the beam energy and the initial pitch angle on the saturation amplitude of the EPMs are discussed in detail. Furthermore, MHD nonlinearity is found to reduce the saturation level of the EPM compared to linear MHD case, while the high-n harmonics have less impact.
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© The Author(s), under exclusive licence to Società Italiana di Fisica and Springer-Verlag GmbH Germany, part of Springer Nature 2023. Springer Nature or its licensor (e.g. a society or other partner) holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.
