Measurement of the force exerted on the surface of an object immersed in a plasma
Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität zu Kiel, 24098 Kiel, Germany
Received: 10 October 2014
Received in final form: 31 January 2015
Published online: 24 March 2015
An experiment is described in which the force exerted by a low-pressure rf plasma on one side of a test surface is measured. The test surface is part of a cubic object immersed in the plasma and is mounted on a pendulum whose small deviations are recorded by a digital camera. The force balance is calibrated by means of an electrostatic method. The measured forces on the surface (4.8 cm2) are in the micronewton range and increase with the plasma density, while an increased collisionality reduces the force. The measured forces are discussed on the basis of a simple model taking into account the momentum fluxes across the sheath edge. It is concluded that ion-neutral collisions in the presheath enhance the force caused by electron pressure and ion flux.
Key words: Plasma Physics
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag 2015