Experimental determination of dust particle charge at elevated pressures

Summary form only given. Experiments with dust particle flow in a horizontal DC discharge tube (experimental facility PK-4) are conducted for particles with radius of 0.6 micron. For relatively high pressures the flow is stable and the charge is calculated from the force balance. Decreasing pressure, a sharp threshold for onset of dust wave instability is observed. We use a linear dispersion relation to find a value of charge for which the transition from stable to unstable regime occurs at experimentally found threshold pressure. The threshold depends strongly on the dust number density and varying the dust density we are able to determine particle charge in the pressure range 30-60 Pa. Molecular dynamic simulations taking into account ion-neutral collisions were also carried out-for the parameters similar to those of the experiments. Results of both experimental methods and simulations show reasonable agreement (within experimental error). The charge obtained is a few times smaller than the OML theory predicts, the result which we associate with the effect of ion-neutral collisions for the neutral pressure range used in experiments.