Dust grain in streaming ions with temperature variation

Abstract

This work presents improved numerical observations to demonstrate influence of the ion-to-electron
temperature ratio on the dust grain in streaming non-Maxwellian ions for a range of ion speeds. Increase
in electron-to-ion temperature ratio influences the ion-grain dynamics substantially and manifests itself as
an enhancement in the wake amplitude. The interplay of streaming ion speed with temperature and their
synergistic impact on the wake potential and density of the grain is discussed in detail. Physical properties
like peak potential and peak position and its dependence on temperature, collision, and streaming speeds
is presented. A comparison of the results obtained using 3D-6V particle-in-cell simulation with that of the
linear response approach is delineated systematically. At lower temperature, peak potential and peak
position exhibit monotonic increase with collision. However, at higher temperature the behavior becomes
non-monotonic and initially exhibits an increase in the peak potential with collision and then a decreasing
trend. For moderate streaming speeds at lower temperatures, splitting of ion focus behind grain is
observed from the density contours as well as three-dimensional potential plots. Our results are
reasonably consistent with that of the earlier results reported using Linear Response formalism,
nevertheless, in certain regimes it endows us with richer physics.