Emission life expectancy of Ir-coated dispenser cathodes for CRTs

Abstract

A compact Ir-coated dispenser cathode was developed for CRT (cathode ray tube) use. To study the emission life of the cathode, an accelerated life test was conducted, using 111% heater voltage. Oxide cathodes were also tested for comparison. The test indicated that the emission of the oxide cathodes decreased to 50% of normal after about 5000 hours. In comparison, after approximately 10000 hours, the emission of Ir-coated dispenser cathodes had decreased less than 5%. The 10000-hour-plus life expectancy of the Ir-coated dispenser cathode was modeled, with the results projecting a life expectancy of approximately 24000 hours at 111% heater voltage. It was estimated that, under normal conditions, the life expectancy of this Ir-coated dispenser cathode would be approximately 100000 hours.<>