Investigating the Binding of Grains in Ultracold Dusty Plasmas

Abstract

Steady-state interaction between stationary grains mediated by plasmas at ultracold superfluid helium temperatures is investigated using particle-in-cell (PIC) simulations with Monte-Carlo collisions. A wide-ranging parametric exploration of interdependence of the physical parameters and its consequence on overall grain–plasma dynamics for cryogenic dusty plasmas is presented. Charging of the grains and the density of trapped ions exhibit a remarkable dependence on the particle shape. Grain charging shares a direct relation with ion flow strength as well and manifests contrasting trends at flow strength $M_{\text {th}}\leq 5$ and $M_{\text {th}}\geq 5$ . A comparison of an isolated grain electric field and potential with the two-grain–plasma system asserts that the field due to an isolated grain is precisely of the same order as the two grain field at subsonic flows. Binding-energy range is estimated to be 0.16–22 eV at $M_{\text {th}}$ = 0–15 and supports the possibility of molecule-like dust structure formation at ultracold temperatures.