Boundary phenomena and thermal properties of dusty plasmas measured using stereoscopic particle image velocimetry

Abstract

Summary form only given. The motion of charged microparticles in dusty (complex) plasmas remains a topic of intense interest to the dusty plasma community. In many experiments, suspended clouds of charged microparticles are observed to have complex internal motion confined within rigid boundaries. Understanding the microparticle dynamics, the thermal properties of the microparticles, and the physics of the particle cloud plasma boundary layer are important, yet unresolved topics. Over the past five years, the Auburn Plasma Sciences Laboratory (PSL) has applied particle image velocimetry (PIV) techniques to make real-time measurements of particle transport in dusty plasmas. In PIV, a pair of laser pulses expanded into a sheet by a cylindrical lens and separated by a time interval dt are used to illuminate the microparticles. A CCD camera oriented perpendicularly to the light sheet and synchronized to the firing of the laser pulses is used to capture the light scattered by the particles. From the displacement of the microparticles between the two images, the two-dimensional motion of the particles in the plane of the light sheet can be reconstructed. In spite of the new insights into microparticle transport and dusty plasma particle dynamics that have been obtained using 2D-PIV techniques, it is clear that information on the third dimension of motion is required to fully understand this complex system. The PSL has recently acquired and installed a stereoscopic PIV (3D-PIV) diagnostic tool for dusty plasma investigations. It employs a synchronized dual-laser, dual-camera system for measuring particle transport in three dimensions. Results will be presented on the use of stereoPIV to characterize perturbed and unperturbed microparticle motion. Additionally, with the availability of three-dimensional velocity vectors, initial attempts to use the PIV data to reconstruct velocity space distribution functions will be discussed.