M-type Cathode Emission Degradation Simulation based on Surface Coating Degradation Mechanisms

Cathodes are key components in vacuum electronic devices (VEDs) which dominate the performance and reliability of the tubes to a great extent. As far as we know, cathode failure mechanisms for M-type cathodes have been studied extensively, and existing cathode degradation models can fit well to measured data in most places, but still have noticeable errors in some places. Among all mechanisms, inter-diffusion & ion bombardment were found to be two main cathode failure mechanisms. In this paper, we show by simulation that both the mechanisms contribute a lot to the final cathode emission degradation mode; and ion-bombardment may lead to earlier knee point time but slower decline of the emission at the end of cathode life compared to inter-diffusion-only mechanism.