A Theory of Dielectric Surface Discharges

We present a theory for the magnitude of blowoff currents measured in electrostatic discharge of spacecraft materials. Observed currents are far larger than can be explained by simple space-charge-limited current calculations. However, a model based on emission enhanced by strong electrostatic fields near the sample edge leads to good agreement with measured currents. Since the total current is proportional to the edge length, the observed dependence of the current on the square root of the sample area is reproduced. Scaling relationships are presented to allow generalization of a few numerical simulations of the space currents during discharges to a wide range of experimental parameters.