High Rotation Rates and Stability in Magnetized Dusty Plasmas

Molecular dynamics (MD) simulations of magnetized dusty plasmas are used to explore the role of competing forces in making 50 µm hollow silica spheres stably rotate, at rates up to an order of magnitude higher than previously reported with much smaller particles. Experiments at Auburn University’s MDPX [E. Thomas, et al. Plasma Phys. 81, 345810206 (2015)] using UMBC’s 15 cm cylindrical glass chamber, motivated this research. In the experiments, argon plasmas were produced using an inductively coupled, 22 – 30 kHz RF source with antennae external to the glass chamber, creating density and temperature gradients that are perpendicular to B and become steeper with increasing B-field strength. We conjecture that such gradients are in turn responsible for dust rotation through ion momentum transfer in the 𝛁P x B direction, as well as for balancing the centrifugal force that appears on the heavy particles during rotation. An experimental setup being built at UMBC to further explore fast rotation and stability, and to compare with the simulations, is also discussed.