Determination of dust grain charge and screening lengths in the plasma sheath by means of a controlled cluster rotation

Abstract

Dusty plasma experiments with flat dust clusters are often performed in the boundary sheath of radio frequency discharges at typical gas pressures of 1–100 Pa. The interaction of the dust grains is usually assumed to be of the Yukawa type, which is determined by the particle charge and the screening length. For the experimental determination of these quantities we present a method that does not require prior knowledge of the plasma parameters. The method is based on the application of centrifugal forces by means of a rotating electrode method (REM). The results are critically compared with an analysis of thermally excited normal modes, which can be studied at pressures below 10 Pa. The REM has a wider range of applicability that can be extended to 100 Pa.