The interaction of powder particles, which are confined in the sheath of an asymmetric capacitively coupled rf-plasma, with an external ion beam has been investigated. In contrast to other experiments where particle displacement and oscillations are excited by electric fields or laser radiation, respectively, we excite the particles by additional energetic ions. By this suitable diagnostics, optimization and adjustment of ion beam sources for thrusters or applications in surface treatment can also be provided. By observing the position and movement of the particles in dependence on the discharge parameters we obtained information on the electric field (2.5 × 103 V m−1) in front of the electrode as well as on the ion drag (1–5 × 10−14N).