Computer simulations of Coulomb crystallization in a dusty plasma

It has been shown experimentally that under the proper conditions, a dusty plasma system can form an ordered, crystalline state known as a Coulomb or dust crystal. This paper uses a computer simulation to model the behavior of such a system while several parameters are changed independently of one another, something that is experimentally difficult to do. The computer program used is a modified Barnes-Hut tree code known as “Box Tree.” Tree codes allow all of the interparticle interactions to be calculated including the medium- and long-range interactions created by distant particles using multipole expansions. The simulation is also used to explore the possibility that the end state of the system may depend (at least in part) on its past history (whether it is initially in a solid or disordered state), or the evolution of κ and Γ themselves. As expected, it is shown that as the coupling parameter increases the amount of order present within a system also increases. Unexpectedly, the simulation also shows that the amount of order present within a dusty plasma system is not necessarily completely determined by Γ_s and κ