A finite-element/method-of-characteristics model of three-dimensional (3-D) electrode geometries with corona discharge is used to predict space charge density, current density, electric potential and electric field in point-to-plane, single-barb plate-to-plane, and hexagonal multiple-barbed plate-to-plate geometries. Although a modification of Peek's formula for the hyperboid-to-plane was initially used to establish a boundary condition at the edge of the corona, predicted total current did not agree with measured values. As a result, it was necessary to use measured current-voltage characteristics to establish the space charge density at the outer surface of the corona sheath. An additional problem in modeling point discharges is specification of shape and size of the corona sheath. Both our results and much earlier work by Trichel suggest that the thickness of the corona sheath cannot be automatically neglected.
Bibliographical noteFunding Information:
Paper MSDAD 95-53, approved by the Electrostatic Processes Committee of the IEEE Industry Applications Society for presentation at the 1994 IEEE Industry Applications Society Annual Meeting, Denver, CO, October 2-7. This work was supported by the U.S. Environmental Protection Agency under Grant R-815740. Manuscript released for publication December 28, 1995.