Levitation of cylindrical particles in the sheath of an rf plasma

Phys Rev E Stat Nonlin Soft Matter Phys. 2001 Mar;63(3 Pt 2):036406. doi: 10.1103/PhysRevE.63.036406. Epub 2001 Feb 27.

Abstract

Microrods were levitated in the collisional sheath of a rf plasma. Rods below a critical length settle vertically, parallel to the electric field, while longer rods float horizontally. Usually rods with other inclinations spin about a vertical axis. These experimental features fit well with a model that includes a theoretical profile for the sheath, a plasma model for the screening length, which increases going deeper in the sheath, and a plasma theory for the charging of the rod's elements. Despite the agreement this paper highlights the need for a better understanding of the charging mechanism of bodies in sheaths and of the transition region in collisional sheaths.