High Reliability, ≫10A/cm2, long-life, dispenser cathodes for space applications with multi-year in-orbit data from the CloudSat mission

This paper describes the dispenser cathode technology and cathode life testing at high current density that together underpin the design of a W-band 2 kW Extended Interaction Klystron developed for the nadir-pointing 94 Ghz radar of the CloudSat Earth Observation satellite. The cathode operates at an emission current density of 11.3 Amps/cm² and, prior to launch, a 99% confidence level of meeting the mission goal of 22,500 hours operating life in orbit was required. The measured performance of the EIK amplifier in orbit is reported together with examples of cloud profiles obtained by the radar. The EIK life model has been validated and, based on the flawless performance of the radar in orbit and the high data yield, the mission has been extended from 2 years to 5.