Switching Between Whistler‐Mode Waves on Inhomogeneities of the Plasma Density and Magnetic Field

AbstractWe present results from the investigation of a transition between two whistler‐mode waves with the same frequency and the parallel wavelength but different perpendicular wavenumbers in the inhomogeneous media consisting of the plasma density and the background magnetic field. We consider transverse inhomogeneities of these quantities. We demonstrate that there are critical values of the plasma density and the magnetic field (which depend on the wave frequency and the parallel wavelength) and the switching between two whistler‐mode waves occurs in the vicinity of these values. We analyze this problem assuming that these critical values are reached inside the finite‐size transition layer between two regions where all the background quantities are homogeneous. We found analytical criteria for the mode switching and we confirmed our results with time‐dependent simulations of the electron‐MHD equations describing whistler‐mode waves in the magnetospheric plasma. We also investigate numerically the dependency of various parameters of the wave switching on the size of the transition region containing critical values of the plasma density and the magnetic field.