| PHYSICS OF GASES, PLASMAS, AND ELECTRIC DISCHARGES |
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Nonlinear Simulations of the Bump-on-Tail Instabilities in Tokamak Plasmas |
| Yumei Hou*, Wei Chen*, Liming Yu , Yunpeng Zou , Min Xu , and Xuru Duan |
| Southwestern Institute of Physics, Chengdu 610041, China |
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| Cite this article: |
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Yumei Hou, Wei Chen, Liming Yu et al 2021 Chin. Phys. Lett. 38 045202 |
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Abstract We reproduce nonlinear behaviors, including frequency chirping and mode splitting, referred to as bump-on-tail instabilities. As has been reported in previous works, the generation and motion of phase-space hole-clump pairs in a kinetically driven, dissipative system can result in frequency chirping. We provide examples of frequency chirping, both with and without pure diffusion, in order to illustrate the role of the diffusion effect, which can suppress holes and clumps; Asymmetric frequency chirpings are produced with drag effect, which is essential to enhance holes, and suppress clumps. Although both diffusion and drag effect suppress the clumps, downward sweepings are observed, caused by a complicated interaction of diffusion and drag. In addition, we examine the discrepancies in frequency chirping between marginally unstable, and far from marginally unstable cases, which we elucidate by means of a dissipative system. In addition, mode splitting is also produced via BOT code for a marginal case with large diffusion.
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Received: 30 November 2020
Published: 06 April 2021
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| PACS: |
52.25.Dg
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(Plasma kinetic equations)
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52.35.Mw
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(Nonlinear phenomena: waves, wave propagation, and other interactions (including parametric effects, mode coupling, ponderomotive effects, etc.))
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| Fund: Supported by the National Key R&D Program of China (Grant No. 2019YFE03020000), the National Natural Science Foundation of China (Grant Nos. 11875021, 11875024, and 12005054), and the Sichuan Science and Technology Program (Grant No. 2020JQQN0070). |
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