Does a banal tungsten field emitter obey the field emission theory

Prompt by new theoretical propositions challenging the Fowler-Nordheim theory, we carried out field emission studies on the archetypal tungsten tip in a UHV environment. We tried different characterization methods in order to extract physical parameters more reliably. However, the different methods proposed so far rely on sweeping the voltage and fitting a straight line. Such methods suffer from the lack of long term stability of cold field emitter due to adsorption of electronegative residual gazes, ion bombardment and surface migration. We show that even with a moderate long term drift of the current, obtaining reproducible results is challenging. We propose another method based on a dual lock-in measurement of the current that could improve the extraction of physical parameters.