Cathode life evaluation based on the evolution of heater power and perveance

Reliability of cathodes is critical for the reliability of traveling wave tubes. Accordingly, the reliability test and life prediction of diodes can provide useful information for cathode and TWT reliability evaluation. In this paper, a simple cathode life prediction method considering the evolving of heater power and perveance is presented. The method is applied on the reliability test data for some glass diode samples and several gun samples. The evaluation results show that the cathode life in the electron guns is much longer than those in the diode samples. And the cathode life prediction result for the diodes, based on the evolving of perveance and heater power for a certain anode current and voltage, is close to the final test result.