Aachen PK 2003 – scientific programme

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P: Plasmaphysik

P 10: Poster II

P 10.38: Poster

Tuesday, March 18, 2003, 17:30–19:15, Foyer

An experiment for measuring ion drag forces on micrometer sized particles — •Markus Hirt and Alexander Piel — IEAP, AG Plasmadynamik, Christian-Albrechts-Universität, 24098 Kiel

The experiment DODO is a double plasma device with a radius of 0.25 m and a length of 1.2 m. At pressures of 10⁻³...10⁻⁵ mbar in argon, two independent filament discharges with plasma densities ranging from 10¹⁴...10¹⁶ m⁻³ and electron temperatures of 2...4 eV can be maintained, separated by a fine mesh grid at -20...-60 V bias. By applying a voltage between the two discharge anodes, an ion beam of well defined ion energy (2...60 eV) is injected into the diagnostic chamber. The ion beam density and energy is measured with an energy analyzer close to the grid. Alternatively, low energy ion wind forces are studied, which flow towards the negatively biased grid. In the diagnostic chamber glass micro-balloons with a diameter of 20...25 µm are dropped from a dust dispenser. The free falling particles are illuminated by a sheet of laser light and observed with a video camera. The drag force of the ion beam results in a deflection of the particle trajectories. The experimental setup, the beam diagnostics and the data analysis techniques are described in this presentation.