Angular emission evolution of the ZrO/W(100) Schottky emitter

An investigation of the uniformity and evolution of the angular emission distribution of the ZrO/W(100) Schottky emitter operated at an angular intensity of 1.0 mA/sr is studied. Emitters of 0.49, 0.90, 0.96, and 1.73 μm apex radius r are studied, and generally for larger radius, the emission distribution is wider and more uniform. Off-axis optical properties are computed in cases where the data were available. However, for a 1.73 μm radius emitter, collapsing net planes (ring collapse) is significant. Uniformity control by temperature for 0.49 and 0.96 μm radii emitter is shown. Over one year, the uniformity for 0.90 μm radius emitter falls, however, the shape change from “stage 1” to “stage 2” does not significantly affect the emission’s uniformity.