ASSTG Articles
Permanent URI for this collectionhttps://hdl.handle.net/2104/5502
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Browsing ASSTG Articles by Author "Douglass, Angela Michelle."
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Item Determination of the levitation limits of dust particles within the sheath in complex plasma experiments(Physics of Plasmas, 2012-01-23) Douglass, Angela Michelle.; Land, Victor; Qiao, Ke; Matthews, Lorin Swint.; Hyde, Truell Wayne.Experiments are performed in which dust particles are levitated at varying heights above the powered electrode in a radio frequency plasma discharge by changing the discharge power. The trajectories of particles dropped from the top of the discharge chamber are used to reconstruct the vertical electric force acting on the particles. The resulting data, together with the results from a self-consistent fluid model, are used to determine the lower levitation limit for dust particles in the discharge and the approximate height above the lower electrode where quasineutrality is attained, locating the sheath edge. These results are then compared with current sheath models. It is also shown that particles levitated within a few electron Debye lengths of the sheath edge are located outside the linearly increasing portion of the electric field.Item The effect of dust charge variation, due to ion flow and electron depletion, on dust levitation(AIP Conference Proceedings, 2011) Land, Victor; Douglass, Angela Michelle.; Qiao, Ke; Matthews, Lorin Swint.; Hyde, Truell Wayne.Using a fluid model, the plasma densities, electron temperature and ion Mach number in front of a powered electrode in different plasma discharges is computed. The dust charge is computed using OML theory for Maxwellian electrons and ions distributed according to a shifted-Maxwellian. By assuming force balance between gravity and the electrostatic force, the dust levitation height is obtained. The importance of the dust charge variation is investigated.