Interplay of single particle and collective response in molecular dynamics simulation of dusty plasma system
Collective response of the plasma medium is well known and has been explored extensively in several contexts. The single particle response is typically treated as collisional interactions leading to dissipative effects. In this manuscript a 2D molecular dynamics (MD) simulation of dusty plasma with Yukawa interactions amidst dust grains have been considered in a strongly coupled regime. It has been shown that disturbances induced in the crystal by introducing highly charged particle elicit both collective and single particle responses. The single particle collisional interaction often generates highly energetic few particles which move with speeds exceeding the acoustic and also the shock velocity (which gets excited by the external moving body inserted in the medium). The dust crystal is observed to crack and deform along the path of these energetic particles. Ultimately as they slow down they excite collective response in the medium. It is thus observed that the medium ahead of the shock gets disturbed by these energetic particles generated by collisional interaction. The trailing shock then sees a disturbed medium. It is thus clear that there is an interesting interplay between the single particle and collective response in the medium which governs the dynamics.