Cathode lifetesting for the EarthCARE extended interaction klystron

This paper presents the testing of EarthCARE extended interaction klystron by lifetest vehicles. The cathodes to be lifetested are the so called Triple alloy cathodes (TA- cathodes), which are standard M-type dispenser cathodes that undergo a coating process to lower the work function. The measured cathode work function at full current is approximately 1.84 eV and exhibiting very small variation amongst the 5 LTV´s. Similarly, the measured knee brightness temperature is very uniform and is around 990 °C at full current.