High emission performance impregnated dispenser cathode

In order to obtain higher emission performance than that of a traditional M-type cathode, we have developed a new type impregnated dispenser cathode. The new cathode is impregnated with a new active substance with molar ratio of 26BaO·29SrO·8Sc₂O₃·7CaO·Al₂O₃. This paper introduces the emission performance, surface active material, and work function of the new cathode. At 1100 °C_B, the DC current density and pulse current density are 30.6±1.0 A/cm² and 171.6±2.8 A/cm², respectively, 2.1 and 5.4 times of that of an M-type cathode. The work function of the new cathode is 1.668±0.002 eV. High concentration O-Al-Sc-Sr-Ba and O-Al-Sc-Ba are found in the pores and at pore edges, respectively. By comparing the emission performances and surface characteristics of as-polished and ascleaned cathodes, it is proposed that, the emission around pore ends forms the major part of the total emission for the new cathodes.