Quantum mechanical investigation of thermionic emission from Os-coated tungsten dispenser cathodes

Understanding the underlying mechanism of thermionic emission is essential for the design of next-generation high-power vacuum electron devices. Previous research mainly focused on the surface work function but few studies on structure/properties of the bulk cathode materials. In this study, we employ quantum mechanical methods to investigate the structure-property relationships governing thermionic emission of Os-coated tungsten dispenser cathodes. We developed a new model to calculate directly the thermionic current densities by incorporating the full electronic density of states of the cathode materials and the calculated work functions of surfaces with Ba adsorption (as in the case of cathode surfaces during operation). This work shows the relative effects of bulk and surface properties on the thermionic emission of Os-coated tungsten thermionic cathodes. The methods from this work can be used for screening/discovery of next-generation thermionic emitters.