Photo-discharging as a path to controlling dust charge in low-temperature plasmas

Charged microparticles (dust) in a plasma environment represent a potential tool for some experimenters and an unwanted contaminant for others. The lack of direct, independent control over the dust's equilibrium charge of the dust particles represents a significant obstacle to improving dust confinement or removal. Recent proof-of-concept tests on the Auburn Dusty Plasma Experiment (DPX) combining Lanthanum Boride (LaB₆) particles with a high-intensity, near-UV source have demonstrated that photoelectric currents can significantly alter the equilibrium properties of the dust; and that by tailoring the light source to the material properties of the dust and the apparatus, this control can be accomplished with minimal perturbation to the background plasma. Probe measurements of the plasma and video analysis of the particle response to the application of UV are presented, and the potential of expanding photo-discharging to other materials and experimental regimes is discussed.