Figure 3

Toroidal RIE: (a) ionic propeller design with actual pin positioning (12.6 cm propeller diameter); the propeller is equipped with a ball bearing unit on which high voltage (HV) is applied and distributed via a copper tape to the pin emitters; (b) 3-D printed toroid; (c) toroidal RIE—the toroid is covered with aluminum foil to form the ground counter-electrode while the propeller is axially positioned above the toroid; (d) cross section details of the toroidal counter electrode design; all dimensions are given in mm.