In situ field emission characterization of high-current cathodes based on commercially available single-walled carbon nanotube papers

This study investigates the potential of commercially available single-walled carbon nanotube (SWNT) papers as high-current field emission cathodes from both macroscopic and microscopic perspectives. By employing an optimized cutting strategy designed to maximize the density of emitting bundles, we demonstrate that macroscopic emission currents of up to 15 mA at 3 kV can be achieved using a 1 cm long sample. To better understand the emission behavior and performance limits of these cathodes, in situ field emission experiments were carried out inside a scanning electron microscope on both individual bundles and groups of bundles. These experiments enabled the characterization of the maximum emission currents as well as the identification of the dominant degradation mechanisms, including mechanical tearing, field evaporation, and vacuum breakdown events. Interestingly, the SWNT papers exhibit a remarkable resilience to vacuum breakdown and maintain excellent emission properties after exposure to ambient air. These results highlight the potential of SWNT papers as practical and robust cathodes for the next-generation vacuum electronic devices.