Thermionic cathode with a mixed LaB₆ and TaC emission layer

A thermionic cathode with a mixed LaB6 and TaC emission layer was investigated. Emission properties of cathodes with LaB6 to TaC weight ratios of 1∶1, 2∶1, and 3∶1 were studied and compared. The work function of the mixed LaB6 cathode was found to be similar to that of polycrystalline LaB6 cathodes. Stable electron emission with a current density of about 30 A/cm2 was achieved with cathode recipe of 3∶1. The cathode can be applied to vacuum electronic devices and dynamic vacuum electron-beam equipments where large electron current density and extremely large area cathodes are demanded.