Two concurrent exponential decays in a vacuum capacitor-resistor circuit: effect of surface charge

The relaxation in a vacuum capacitor-resistor circuit is comprised of two exponential decays, one caused by surface charge and the other by the decay of energy stored between the capacitor plates. A simple phenomenological model of this relaxation is shown to be supported by measurements even though Maxwell’s equations are difficult to apply in this case. Similar behavior is also observed for polypropylene capacitors, indicating that this surface charge effect is applicable to all capacitors and potentially other circuit components.