[en] This paper describes the investigation and application of scandate cathodes in Beijing Vacuum Electronics Research Institute (BVERI). The data of emission performance and lifetime were acquired both in closed-spaced diodes and in microwave tubes. Evaporation rates and gas poisoning properties have been determined. From the results of a series of diode experiments and the feedback information of practical usage in tubes, there are three key factors that in our opinion limit the practical application of scandate cathodes in general. These are no obvious saturation onset of I/U characteristics, weak ion bombardment resistivity and non-uniform emission. The authors conclude that to a certain extent, impregnated scandate cathodes (I-Sc) can be used as alternative electron sources instead of M-type cathode in microwave tubes

[en] We investigated high current density emission capabilities of M-type cathodes used for vacuum electron devices (VEDs). The experimental results of emission and lifetime evaluating in both close-spaced diode structure and electron gun testing vehicles are given. Emission current densities measured in the diode structure at 1020 deg. C_Br in the CW mode were above 10 A/cm²; while in electron gun testing vehicles, emission current densities were above 8 A/cm² in CW mode and above 32 A/cm² in pulsed mode, respectively. The current density above 94 A/cm² has been acquired in no. 0306 electron gun vehicle while the practical temperature is 1060 deg. C_Br. For a comparison some of the data from I-scandate cathodes are presented. Finally, several application examples in practical travelling wave tubes (TWTs) and multi beam klystrons (MBKs) are also reported