Comparison of noise and emission characteristics between individually operated NbC/Nb and Ir field emitter array cathodes and etched W[100] emitters

Oriented single crystal tungsten field emitters mounted on a filament were fabricated using electrolytic etch. The emission pattern of the W emitters was observed and recorded using digital movie camera, allowing the correlation of phosphor patterns with continuous current data. The W tips were operated at room temperature and at temperatures up to 1000 K. Current fluctuations relative to the mean within consecutive short time segments were recorded and their distribution was plotted. The mean ΔI/I was determined as a function of residual pressure. I(V) characteristics were measured. Emission stability was analyzed using s-i charts. The results were compared to the short-term current fluctuations previously observed from single NbC/Nb field emitters.