Electron emission and structure stability of carbon nanotube cold cathode driven by millisecond pulsed voltage

Abstract

The carbon nanotube (CNT) cold cathode can provide a high current and current density for microwave devices, which normally work under pulse mode. In this work, we studied the electron emission characteristics and strucutre stability of a CNT cold cathode in millisecond pulse mode. Peak current and average current are both key parameters for the performance of cold cathode. Increasing the duty ratio proved an effective way to increase the average current and average power of the cold cathode. The pulsing field emission characteristics of CNT cold cathode was optimized by modulating the pulse width, pulse interval time, and duty ratio. The average current in millisecond pulse mode was three orders of magnitude greater than that when using microsecond pulses. The average current also linearly increased with the duty ratio. The morphology of CNT films after pulsing and DC field emission was investigated to reveal the stability and the vacuum breakdown mechanism. The thermal equilibrium of the CNT was analyzed to reveal its underlying mechanism. This work provides a practical strategy for the application of CNT cold cathodes in high-power microwave devices.