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Electromagnetic Waves and Lasers
Published in Hitendra K. Malik, Laser-Matter Interaction for Radiation and Energy, 2021
In view of this, the magnetosonic wave is also called an acoustic wave. In the absence of magnetic field B→0,vA=0 and the dispersion relation takes the form of that of acoustic wave and hence, the magnetosonic wave becomes an ordinary ion acoustic wave. However, in the absence of ion and electron temperatures, vs=0, and the dispersion relation carries onlyvA terms along with c. Under this situation, ωk>vA and the wave is said to be a fast hydromagnetic wave.
The Physics of Ion Cyclotron Heating In Tokamaks
Published in R A Cairns, A D R Phelps, P Osborne, Generation and Application of High Power Microwaves, 2020
This is the compressional Alfven wave, or fast wave (FW) (in the Russian literature also known as magnetosonic wave), which is the natural candidate for plasma heating and current drive in the ion cyclotron range of frequencies. Excluding insignificantly low densities, in a plasma with a single species of ions L and S are positive for ω<Ωci and negative for ω<Ωci, while R is always positive (actually, larger than unity). The fast wave, therefore, propagates only if if n2<R. The surface where the equality n‖2=R is satisfied is called the ‘low-density cutoff’. Waves with n12>1 are evanescent in vacuum, and propagate only above this cutoff. This puts an upper limit to the values of Thb2 which can be efficiently launched from outside.
Chiral fermion asymmetry in high-energy plasma simulations
Published in Geophysical & Astrophysical Fluid Dynamics, 2020
J. Schober, A. Brandenburg, I. Rogachevskii
The chiral asymmetry also affects the dispersion relation for MHD waves in a plasma. If a chiral instability is excited, it has a direct effect on the the frequencies and amplitudes of Alfvén and magnetosonic waves through the amplification of the magnetic field. How the dispersion relation in chiral MHD differs from the one in classical MHD has been shown in Rogachevskii et al. (2017). The general expression for a compressible flow is given by where is the frequency of Alfvén waves in the absence of the CME. The complexity of the dispersion relation (26) indicates that in chiral MHD, the Alfvén and magnetosonic waves are strongly affected by a non-zero . For solutions of Equation (26) as a function of the angle between the wavevector and the background magnetic field, we refer to Figure 1 of Rogachevskii et al. (2017). In summary, the frequencies of the Alfvén wave and the magnetosonic wave are increased for a weak magnetic field, while the frequency of the slow magnetosonic wave is decreased in chiral MHD.
Nonlinear waves coupled by magnetosonic wave and ion acoustic wave in overdense plasma
Published in Waves in Random and Complex Media, 2023
Lin Wei, Zhong-Zheng Li, Wen-Shan Duan
The coupling between different types of the nonlinear waves has been studied [23–25]. The nonlinear coupled equations of magnetosonic wave and Alfvén wave in the presence of the ponderomotive force of the magnetosonic wave are given [24]. In addition, the nonlinear coupled equations of magnetosonic wave and ion acoustic wave in the presence of the ponderomotive force of the magnetosonic wave are also given [23]. The coupling between different nonlinear waves may produce the modulational instabilities [25] which may result in the rogue waves (RWs), breathers and other nonlinear waves [26–28].