High current density ternary-alloy-film dispenser cathode for terahertz vacuum devices

Dispenser cathode is used in microwave tubes as source of electrons. We investigate high current density emission capabilities of alloy-coated cathodes used for terahertz vacuum devices. In this paper the developmental work carried out on ternary-alloy-film cathode (2Os:2Re:1W) and the results are presented. The cathodes were tested inside a closed spaced diode and also analytical chamber containing Auger Electron Spectroscopy (AES), Thermionic Emission Microscope (THEM) facility. Emission current densities measured in the diode structure at 1300° K temperature were above 60 A/cm
²
. The work function was found 1.72 eV using 73% slope method. To ensure the life of the cathode accelerated life test has been carried out in closed spaced diode at 1300° K temperature.