Field emission from air-exposed silicon and other surfaces typically occurs at energies up to several volts below the Fermi level, and the energies can change substantially during emission. We conclude this behavior results from emission from initial states in a dielectric (oxide) surface coating, and that the energies of these states change relative to the emitter Fermi level due to changing oxide state density and charge density. When emission occurs below the bulk Fermi level, energy is deposited into the emitter. In some cases this energy can be coupled to chemical bonds, creating states in the oxide and improving electron transport. If the power density deposited this way becomes excessive, oxide breakdown and arc initiation can result. Thus preventing excessive emission current at potentials more than 1-2 V positive relative to the bulk Fermi,level may prevent arc initiation. We propose that might be done by building a second (filter) aperture above each gate aperture in an array, and placing the aperture at a low,positive voltage relative to the emitter contact. That structure creates a potential barrier for emitted electrons, which will cause those electrons emitted at excessively positive potentials to be returned to the gate electrode. A circuit element in series with the gate electrode will reduce the gate voltage, thereby limiting the current emitted at low energy. To limit or regulate the total emission current, a small resistor or other circuit element can be placed in series with the emitter, forcing the emission energy to be reduced in response to a given current.