Cavitation by Nonlinear Interaction Between Inertial Alfven Waves and Magnetosonic Waves in Low Beta Plasmas

This paper presents the model equations governing the nonlinear interaction between dispersive Alfven wave (DAW) and magnetosonic wave in the low-beta plasmas (beta << m(e)/m(i); known as inertial Alfven waves (IAWs); here beta = 8 pi n(0)T/B(0)(2) is thermal to magnetic pressure, n(0) is unperturbed plasma number density, T (= T(e) approximate to T(i)) represents the plasma temperature, and m(e)(m(i)) is the mass of electron (ion)). This nonlinear dynamical system may be considered as the modified Zakharov system of equations (MZSE). These model equations are solved numerically by using a pseudo-spectral method to study the nonlinear evolution of density cavities driven by IAW. We observed the nonlinear evolution of IAW magnetic field structures having chaotic behavior accompanied by density cavities associated with the magnetosonic wave. The relevance of these investigations to low-beta plasmas in solar corona and auroral ionospheric plasmas has been pointed out. For the auroral ionosphere, we observed the density fluctuations of similar to 0.07n(0), consistent with the FAST observation reported by Chaston et al. (Phys. Scr. T84, 64, 2000). The heating of the solar corona observed by Yohkoh and SOHO may be produced by the coupling of IAW and magnetosonic wave via filamentation process as discussed here.