Corona current distributions at the ground plane of barbed plate-to-plane negative discharge configurations are measured using an X-Y traversing ground plane containing an electrically isolated probe area. The effects of barb length, barb point radius of curvature, barb pattern, applied voltage, and plate-to-plane spacing on the current distribution are examined. The current distributions are visualized with oxidation patterns on a copper ground plane. Barb top-to-plane spacing and applied voltage control maximum current density, while barb length, barb spacing, and pattern govern current density uniformity. A hexagonal barb pattern is suggested for use in electrostatic precipitators.