Long-life high-reliability Ir-coated dispenser cathode

A long-life high-reliability Ir-coated dispenser cathode has been developed. To study the life characteristics of Ir-coated dispenser cathode, which is provided with a surface alloy layer of εII, extended life tests were conducted over 10,000h. From this life data, this cathode was estimated to have a 200,000h life at 920°Cb with 0.8A/cm², and to have a 100,000h life at 980°Cb with 2.5A/cm²before emission decreases by 4%. Further, the experiment equation for surface Ir concentration of the cathodes was deduced from the results of surface analysis. Using this equation, the surface alloy layer was evaluated as extremely stable without substantial degradation during cathode life. Thus, the Ir-coated dispenser cathode has been proved to be exceedingly durable and highly reliable.