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Stabilization of a tungsten cold field emitter
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View: Figures


Image of FIG. 1.
FIG. 1.

(Color online) Schematic of experimental field-emission measurement. The experiment was performed in a SEM gun evacuated by ion pumps and a supplemental NEG pump. The pressure of the top chamber was .

Image of FIG. 2.
FIG. 2.

(Color online) Time variation of total and probe currents and noise of probe current from tungsten emitter. As for the probe current, a stable “plateau region,” which lasted about 4 h with low noise, appears just after flashing.

Image of FIG. 3.
FIG. 3.

(Color online) Schematic of experimental measurement of emission pattern. The experiment was performed in a chamber evacuated by an ion pump and titanium sublimation pump. The chamber pressure was . The emission pattern was projected on the fluorescent screen in front of the emitter. Probe current from the (310) plane was collected by a Faraday cup through a probe hole. Time change of emission pattern was observed through a view port.

Image of FIG. 4.
FIG. 4.

(Color online) (a) Time variation of probe current emitted from tungsten (310) crystal plane. Arrows (a)–(f) in (A) indicate the corresponding images of emission pattern in (B). (B) Change of emission pattern around the (310) plane. (C) Schematic of typical crystal planes composing the emission pattern in (B), (a). The black spots indicate dark area in the pattern. In the early period of emission [(B), (a)–(c)], the dark area around the {211} and (100) planes expanded outward, while the brightness around {310} was maintained. As time passed, the bright area changed from a circular to a rhombic shape owing to the expansion of the dark area around {211} planes [(B), (d)]. The bright area then darkened with time, but the brightness around the {310} planes still remained [(B), (e)–(f)].

Image of FIG. 5.
FIG. 5.

(Color online) Time variation of total current, probe current, and noise under intermittent mild flashings at . The arrows above the graph indicate when the mild flashings were performed. The plateau region in the probe current was extended to 12 h while noise is kept to less than 3%.


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752b84549af89a08dbdd7fdb8b9568b5 journal.articlezxybnytfddd
Scitation: Stabilization of a tungsten ⟨310⟩ cold field emitter