A two-fluid modeling of kinetic Alfvén wave turbulence |
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| Authors: | Sanjay Kumar Navin Kumar Dwivedi R P Sharma Y-J Moon |
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| Institution: | 1.School of Space Research,Kyung Hee University,Yongin,South Korea;2.Shandong Provincial Key Laboratory of Optical Astronomy and Solar-Terrestrial Environment, Institute of Space Sciences,Shandong University,Weihai,People’s Republic of China;3.Space Research Institute,Austrian Academy of Sciences,Graz,Austria;4.Centre for Energy Studies,Indian Institute of Technology (IIT) Delhi,New Delhi,India |
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| Abstract: | We present an analytical model to explore the magnetic field turbulent spectrum by coupled high-frequency kinetic Alfvén wave (KAW) and slow mode of Alfvén wave (AW). The spectrum is computed as a realization of energy cascades from larger to smaller scales for a specific case of solar wind plasma at 1 AU. A two-fluid technique is implemented for the derivation of model equations leading two wave modes. These coupled, nonlinear equations are solved numerically. The nonlinearity in the system arises due to nonlinear ponderomotive force, which is believed to be responsible for the wave localization and magnetic islands formation. The numerical results show that the magnetic islands grow with time and attain a quasi-steady state after the modulation instability is saturated. The magnetic field spectrum and associated spectral indices are computed near the time of saturation of instability. The simulated spectrum in dispersion region follows a power-law with an index of ?2.5. The steeper spectrum could be attributed as energy transfer from larger to smaller scales and helps to study turbulence in solar wind. The magnetic field spectrum and spectral index show a good agreement with the observation of solar wind turbulent spectra. |
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