Experiments are performed in which dust particles are levitated at varyingheights above the powered electrode in a RF plasma discharge by changing thedischarge power. The trajectories of particles dropped from the top of thedischarge chamber are used to reconstruct the vertical electric force acting onthe particles. The resulting data, together with the results from aselfconsistent fluid model, are used to determine the lower levitation limitfor dust particles in the discharge and the approximate height above the lowerelectrode where quasineutrality is attained, locating the sheath edge. Theseresults are then compared with current sheath models. It is also shown thatparticles levitated within a few electron Debye lengths of the sheath edge arelocated outside the linearly increasing portion of the electric field.
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