Solar Wind Penetration into Dusty Magnetospheres creates Electrostatic Waves and Structures
The low frequency electrostatic perturbations have been investigated in a bi ion plasma in the background of static dust. It is shown that the field aligned shear flow of both the ions produce low frequency electrostatic instabilities and create nonlinear structures, the double layers and the solitons. The general theoretical model is applied to the magnetospheres of Jupiter (with positively charged dust) and Saturn (with negatively charged dust) which have oxygen ions in addition to protons. This model predicts the existence of extremely low frequency electrostatic waves with real frequencies of the order of a milli Hertz (mHz) to several mHz and this range of frequencies have been reported in literature for these plasma environments. The estimated width of the nonlinear structures vary from a few hundred meters to a few kilometers. These structures are similar to that observed in the oxygen and oxygen hydrogen plasmas in Earth's upper ionosphere which is free from dust.