Transitions between reciprocal and non-reciprocal interactions in complex plasmas*

Complex plasmas are composed of electrons, ions, neutrals, and micron-sized, charged particles (dust). Under microgravity conditions, the dust particles can fill the plasma volume, which enables the study of small-scale inter-dust forces. In this work, we seek to determine how the thermodynamic properties of a complex plasma evolve when the inter-particle potential is modified from a non-reciprocal to a reciprocal structure. In the Plasma Kristall-4 (PK-4) microgravity laboratory on the International Space Station (ISS), particles are injected into a dc glow discharge plasma and flow along an axial electric field. Upon the application of a periodic oscillation of the electric field ("polarity switching"), there is change in the spatial ordering of the particles. This presentation discusses initial results from molecular dynamics simulations that are motivated by these experiments. It is shown that modifying the interaction potential affects the spatial ordering and thermal properties of a dusty plasma. This presentation will also present supporting experimental results on these processes.