Field electron emission induced glow discharge in a nanodiamond vacuum diode

Abstract

The present letter extends the prior findings on self-induced heating of solid state field emission devices. It was found that a vacuum diode (base pressure ∼ 10 −9 Torr), that makes use of graphiterich polycrystalline diamond as cathode material, can switch from diode regime to resistor regime, to glow discharge plasma regime without any external perturbation, i.e. all transitions are self-induced. Combined results of in situ field emission microscopy and ex situ electron microscopy and Raman spectroscopy suggested that the nanodiamond cathode of the diode heated to about 3000 K which caused self-induced material evaporation, ionization and eventually micro-plasma formation. Our results confirm that field emission, commonly called cold emission, is a very complex phenomenon that can cause severe thermal load. Thermal load and material runaway could be the major factors causing vacuum diode deterioration, i.e. progressive increase in turn-on field, decrease in field enhancement factor, and eventual failure. arXiv:1811.04186v1 [cond-mat.mtrl-sci]

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