Abstract
Low temperature operating cathodes produced by hot isostatic pressing (HIP) have been developed. This new cathode, which has the advantages of both oxide cathodes and dispenser cathodes, was achieved by HIP, although sintered cathodes have not been successful thus far. Nickel powder and Ba-Sr-Ca carbonate (emitter) powder are mixed, pressed and subsequently encapsulated into a glass capsule under vacuum. HIP was performed at 1373 K and 130 MPa. The carbonate emitter was converted into oxide by heat treatment in a cathode ray tube. The optimized operating temperature of the HIP cathode was 1053 K, which was almost the same as that of oxide cathodes and was 150 K lower than that of dispenser cathodes. The life test of the HIP cathodes revealed only less than 10% decay after 30000 h under a high current density of 3 A/cm2. In contrast, oxide cathodes showed about 50% decay after only 1000 h under the same current density.
