Collisional Plasma Wakes of Small Particles

Dynamical screening and wake effects in complex plasmas have been the subject of many investigations, including theoretical [1,2] as well as experimental work [3]. It was shown using Linear Response (LR) theory that the characteristic features of the wake potential for non-Maxwellian plasma are qualitatively different from Maxwellian streaming ions. Here, the electrostatic potential of a dust grain in streaming ions in the presence of collisions is computed using three-dimensional particle-in-cell (PIC) code ‘COPTIC’ [4]. We compare our numerical results (PIC) with the wake potential obtained from the LR formalism as well as hydrodynamic simulations for Maxwellian case in linear as well as nonlinear regime. Wakes exhibit interesting physical characteristics for magnetized streaming ions [5]. We discuss the physics of distribution function, flux etc. around the grain and present a parametric study of wake peak position, peak potential vs. collision frequency for the non-Maxwellian streaming plasmas in the absence and presence of magnetic field.