Resonant Decay of Kinetic Alfvén Waves and Implication on Spectral Cascading
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arXiv
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| Autores principales: | , , |
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| Formato: | Preprint |
| Publicado: |
2024
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| _version_ | 1866911749036310528 |
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| author | Shen, Kexun Cheng, Zhiwen Qiu, Zhiyong |
| author_facet | Shen, Kexun Cheng, Zhiwen Qiu, Zhiyong |
| contents | A general equation describing the resonant nonlinear mode-coupling among kinetic Alfvén waves (KAWs) is derived using nonlinear gyrokinetic theory, which can be applied to study the potentially strong spectral energy transfer of KAWs. As a first application, the parametric decay of a pump KAW into two sideband KAWs are studied, with particular emphasis on the cascading in perpendicular wavenumber. It is found that, for the "co-propagating" cases with all three KAWs propagating in the same direction along the equilibrium magnetic field line, it exhibits a dual cascading character in the perpendicular wavenumber space; while for the "counter-propagating" cases with one sideband propagating in the opposite direction with respect to the pump wave, it instead, can exhibit both dual and inverse cascading behaviors. The implications on SAW instability nonlinear saturation and charged particle transport in fusion plasmas is also discussed. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2401_02711 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | Resonant Decay of Kinetic Alfvén Waves and Implication on Spectral Cascading Shen, Kexun Cheng, Zhiwen Qiu, Zhiyong Plasma Physics A general equation describing the resonant nonlinear mode-coupling among kinetic Alfvén waves (KAWs) is derived using nonlinear gyrokinetic theory, which can be applied to study the potentially strong spectral energy transfer of KAWs. As a first application, the parametric decay of a pump KAW into two sideband KAWs are studied, with particular emphasis on the cascading in perpendicular wavenumber. It is found that, for the "co-propagating" cases with all three KAWs propagating in the same direction along the equilibrium magnetic field line, it exhibits a dual cascading character in the perpendicular wavenumber space; while for the "counter-propagating" cases with one sideband propagating in the opposite direction with respect to the pump wave, it instead, can exhibit both dual and inverse cascading behaviors. The implications on SAW instability nonlinear saturation and charged particle transport in fusion plasmas is also discussed. |
| title | Resonant Decay of Kinetic Alfvén Waves and Implication on Spectral Cascading |
| topic | Plasma Physics |
| url | https://arxiv.org/abs/2401.02711 |