Pulsed shear motion in a three-dimensional dusty plasma under microgravity conditions*

Shear motion of dust particles in a strongly-coupled dusty plasma under microgravity conditions was investigated using the European Space Agency's facility PK-4 on the International Space Station. The particles were trapped in a plasma powered by a DC voltage that switches its polarity periodically. They self-organized themselves into a structure resembling a solid or a cold liquid. A manipulation laser beam pushed a slab of particles to move through the surrounding sample region. The power of the laser was modulated, causing a sudden onset of pulsed shear motion among the particles. We tracked particle motion using video cameras. Results including the spatial and temporal variations of dust fluid velocity will be shown.