Experiments in flowing and freely expanding dusty plasmas

has been approved by the Examining Committee for the thesis requirement for the Doctor of Philosophy degree in Physics at the May 2015 graduation. ACKNOWLEDGEMENTS I extend my sincere gratitude to my advisor Robert Merlino for his invaluable guidance, support, and discussions throughout my graduate education. I would also like to thank Su-Hyun Kim and Jonathan Heinrich for their assistance, mentoring and discussions. I would also like to thank Michael Miller for his technical knowledge and support. ABSTRACT Dusty plasmas are an important area of research pertaining to astrophysical problems, fusion research and plasma etching devices. They can also be used to study phase transitions and fluid dynamics. I study a dusty plasma produced in a DC glow discharge device. The chamber is a stainless steel cylinder 0.6 m in diameter and 0.9 m long. A stainless steel disk 3.2 cm in diameter acts as the anode and the walls act as the cathode. The discharge current is set between 1-10 mA and the voltage at the anode between 250 – 300 V. Dust is initially on a tray beneath the anode, and becomes trapped in the anode glow naturally with high discharge current. A secondary cloud can be made at a different location using a biased mesh. I make experimental observations of the dynamics of the secondary cloud as well as the unique interaction of the dust with a wire loop near the anode. First, I describe the interaction of the secondary cloud with a wire when the cloud is released to flow back to the primary cloud. A detached bow shock is observed as the cloud encounters an obstacle, and an elongated teardrop shaped void is formed downstream of the obstacle. Second, a continuous flow is set up using a biased ring. The potentials of the ring and anode create a converging-diverging electrostatic potential structure that accelerates dust particles into a thin stream in the diverging section. The interaction of this stream and a wire obstacle is described. Finally, the potentials of the mesh and anode are suddenly switched to float simultaneously to observe the secondary cloud expansion in the afterglow plasma. The iv rate of expansion is shown to depend inversely on the background pressure in the range of 100-200 mTorr. The expansion shows a separation in the cloud and probable Coulomb-like expansion when compared to theoretical predictions of the rate of expansion of the outer edge …