Emission measurements and simulation of silicon field-emitter arrays with linear planar lenses

Results of beam collimation experiments on linear field-emitter arrays with linear planar lenses are summarized. The electron beam is imaged on a phosphor screen. In general, as lens voltage is reduced relative to the gate voltage, the elliptically shaped screen images narrow, becoming fine lines with emission currents showing only modest reductions. This reduction of emission current can be overcome by increasing the gate voltage only a few volts without affecting beam collimation. As the lens voltage is reduced, screen current decreases relative to emission current while gate current increases, indicating that some emitted electrons in this linear lens geometry cannot propagate to the anode screen. Experimental data and qualitative modeling are in fair agreement.