Characterizing the Field Emission Properties of Vertically Aligned Carbon Nanotube Cathodes for RF Sources

Carbon nanotubes (CNTs) have long held promise as field emitters due to their field enhancing geometry. In this study, an automated measurement system and diode for DC and pulsed testing was designed to facilitate precise and repeatable measurements of the field emission current, enabling a thorough and accurate assessment of vertically aligned carbon nanotube cathode performance for different geometries and growth processes. Specifically, emission current, turn on field, time dependent current stability, and device lifetimes were studied. Electrostatic simulations were conducted in COMSOL to investigate the field enhancement of different CNT cathode geometries to provide further understanding of the geometric effect on field emission mechanisms. The findings of this research aim to explore the viability of CNT emitters as a potential alternative to thermionic cathodes for use in high powered RF systems.