Modeling the Acceleration Process of Dust in the Solar Wind

Abstract:

In previous studies we have identified structures created by nano-dust in the solar wind, and we have observed the expected draping and diverting signatures of such structures using well-spaced multi-spacecraft observations. In this study, we reproduce such an interaction event with our multi-fluid MHD model, modeling the dust particles as a fluid. When the number density of dust particles is comparable to the solar wind ions, a significant draping in the IMF is created, with amplitude larger than the ambient fluctuations. We note that such a density is well above several nano dust particles per Debye sphere and a dusty fluid is appropriate for modeling the dust-solar wind interaction. We assume a spherical cloud of dust travelling with 90% solar wind speed. In addition to reproducing the IMF response to the nano-dust at the end-stage of dust acceleration, we model the entire process of such acceleration in the gravity field of the inner heliosphere. It takes hours for the smallest dust with 3000 amu per proton charge to reach the solar wind speed. We find the dust cloud stretched along the solar wind flow. Such stretching enhances the draping of IMF, compared to the spherical cloud we used in an earlier stage of this study. This model will be further used to examine magnetic perturbations at an earlier stage of dust cloud acceleration, and then determine the size, density, and total mass of dust cloud, as well as its creation and acceleration.