Eur. Phys. J. D (2015) 69: 91
https://doi.org/10.1140/epjd/e2015-50743-2

Regular Article

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

^a e-mail: trottenberg@physik.uni-kiel.de

Received: 10 October 2014
Received in final form: 31 January 2015
Published online: 24 March 2015

Abstract

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.