Patent ID: 8575842

Claim:
An apparatus comprising: a cathode; an anode, wherein the anode and cathode are receptive to a first power source to produce an anode electric potential higher than a cathode electric potential; a gate positioned between the anode and the cathode, the gate being receptive to a second power source to produce a gate electric potential selected to induce electron emission from the cathode for a first set of electrons having energies above a first threshold energy; a suppressor positioned between the gate and the anode, the suppressor being receptive to a third power source to produce a suppressor electric potential selected to induce electron emission from the anode; at least one region including gas located between the cathode and anode; and at least one path traversable for a first portion of the first set of electrons, extending from the cathode, through the gate, through the region including gas, through the suppressor, and to the anode.