Laser-based measurement of 3-dimensional dust trajectory in plasma

Dusts, produced by plasma-wall interactions or gas phase chemical reactions in various plasmas including tokamak plasmas and processing plasmas, brings about many negative concerns in the operational and safety aspects [1]. Therefore, many efforts on developing dust diagnostics and control/removal techniques of dusts from the plasma environments have been made during the last decade [2,3]. Among various dust diagnostics adopted in plasma experiments, the laser based diagnostics are attractive because they are non-intrusive and time-resolved in-situ. In this study, a laser diagnostic technique for 3-dimensional dust trajectory by utilizing two video cameras and a sheet laser beam with a multiple beam pass method is presented, which results in improved sensitivity than previously developed methods. In addition, 3-dimensional dust trajectories are measured with different neutral drag and thermophoresis varied by neutral gas flow rates and neutral temperature gradient, respectively. \\[0pt] [1] S. H. Hong, C. Grisolia, V. Rohde, P. Monier-Garbet, Tore Supra Team, and ASDEX Upgrade Team, Nucl. Fusion 50, 035002 (2010). [2] A. L. Roquemore, W. Davis, R. Kaita, C. H. Skinner, R. Maqueda, and N. Nishino, Rev. Sci. Instrum. 77, 10E526 (2006). [3] W. P. West, B. D. Bray, and J. Burkart, Plasma Phys. Control. Fusion 48, 1661 (2006).