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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 × 10 3 V m −1 ) in front of the electrode as well as on the ion drag (1-5 × 10 −14 N).

In this work we characterize a low-power radio-frequency atmospheric plasma (plasma needle) in terms of dissipated (input) and emitted power per unit surface (power outflux). The plasma is a non-thermal source, used for treatment of biological tissues and other vulnerable surfaces. A calibrated thermal probe is used to determine the power emitted from the plasma towards treated surfaces. Transmission of the emitted plasma power through various media (solid layers, fluids and physiological media) is studied for a broad range of plasma conditions. These data give insight into various contributions to the power outflux (thermal conduction, radiation and energetic species), as well as the penetration depth of the plasma into treated objects. The power outflux is shown to be a very important parameter, which determines the performance of the plasma tool. For the effectiveness and reproducibility of the process the power outflux is much more important than the nominal power setting. Thus, a thermal probe should become a standard control unit in surface processing reactors.

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