Erlangen 2026 – scientific programme

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P: Fachverband Plasmaphysik

P 8: Low Pressure Plasmas II

P 8.6: Talk

Tuesday, March 17, 2026, 18:00–18:15, KH 01.020

The influence of the electrode material on rf plasma sheaths observed by force measurements on optically trapped microparticles — •Philipp Naudiet, Jessica Niemann, Viktor Schneider, and Holger Kersten — Institute of Experimental and Applied Physics (IEAP), Kiel University

Using optically trapped microparticles, the sheath of a plasma can be probed in a non-invasive way. To investigate the effects of secondary electron emission from the surface of the electrode on the sheath of a capacitively coupled radio frequency plasma, the force upon single optically trapped microparticles was tracked along a path from the bulk of the plasma through the sheath towards the electrode. These measurements were carried out for electrodes made of stainless steel, aluminium, titanium and glass-ceramic, under a range of different argon gas pressures and rf voltages.

We observe significant changes in the electric field force onto the microparticle depending on the electrode material. We attribute the changes in the location of the sheath edge and the forces onto the particle to the emission of secondary electrons from the surface of the electrode, and resulting changes of the particle's charge.

Keywords: plasma diagnostics; radio frequency discharges; plasma sheath; secondary electron emission