Description
It was found that metal-coated melamine formaldehyde particles suspended in an rf plasma can exhibit active behavior when they are illuminated by lasers. Inhomogeneities and defects of the coating lead to the emergence of photophoretic forces, resulting in a behavior similar to Janus particles. In laboratory experiments, a fraction of 10 to 20 % of the particles showed such active behavior.
Here, silver and gold-coated particles were used in the Zyflex chamber on parabolic flights. The setup allowed to study void-free extended dust clouds with minimal external stress. A section of the dust cloud was observed with a stereoscopic four-camera setup, allowing to reconstruct particle trajectories in three dimensions. The influence of the strength of the laser illumination was studied. A characterization of the active dust clouds using the three-dimensional data will be presented in this contribution, including velocity distributions as well as other statistical measures.
This work was funded by DLR (German Aerospace Center) grants 50WM2161 and 50WM2561.