Interplay of dust ordering and potential structures in magnetized low temperature plasmas

Imposed ordering can occur when micron-sized dust particles in a magnetized plasma align with the geometry of a conducting mesh placed above them. First observed in the Magnetized Dusty Plasma eXperiment (MDPX) [E. Thomas et al., Phys. Plasmas 22, 030701 (2015)], dust formed 4-fold symmetric structures matching a square-gridded mesh. We hypothesize that elongated electric potential structures from the mesh drive the dust motion to mimic the mesh pattern. Imposed ordering varies with magnetic field, neutral pressure, and mesh geometry. Experiments spanned a wide range of pressures and magnetic fields using two mesh types: a perforated sheet and an interwoven mesh. As magnetization increases and dust transitions from 6-fold self-ordering to 4-fold imposed ordering, motion becomes increasingly 3D and maps the potential. We quantify dust phases using particle tracking as a first step toward inferring the potential structures. This work has potential relevance across multiple fields, as the system can act as a macroscopic analog for phenomena such as phase transitions in crystal structures and the pinning and depinning of particles on ordered substrates [C. Reichhardt & C. J. Olson Reichhardt, Rep. Prog. Phys. 80, 026501 (2017)].