Optimization of High-performance Field Emission Rare Earth Tungsten Alloy Cathodes

he cathodes, as the electronic emission source of all kinds of electronic vacuum devices and spacecraft potential control system, its performance not only affects the overall efficiency of the equipment, but also limits the most important factors of the system long life and high reliability, and its emission principle mainly includes thermal emission and field emission, etc. Therefore, based on first-principles calculations using density functional theory, this study constructs atomic models of W cathode surfaces doped with different rare earth atoms. Using a (2×2×1) W(001) surface model, 1 ML of O atoms is adsorbed on the top site of the surface, followed by doping rare earth atoms (La, Ce, Y) into the W-O lattice vacancy sites. The work functions of the system with rare earth atom coverages of 0.5 ML and 1 ML were calculated. Through liquid phase synthesis, plasma discharge sintering, and heat treatment, nano-scale second-phase rare earth oxides (La?O?, CeO?, Y?O?, etc.)–tungsten cathodes were produced. Different ignition experiments were designed to simulate various operating conditions. The cascade arc plasma source was used for mass-loss and lifetime prediction tests on the cathode materials. After testing, SEM and EDS microscopic characterizations of the cathode materials were conducted to analyze their composition, morphology, and elemental distribution. Optimization results reveal that the W-La, W-Ce, and W-Y cathodes prepared with this method exhibit excellent ablation resistance and plasma bombardment endurance at high temperatures. The nanoscale dispersion of the doped phases endows the cathode with superior electron emission properties, enhancing the overall efficiency of the system. Under plasma density of 101?/m3 and working temperature of 2000°C, the projected lifetime of rare earth tungsten alloy cathodes exceeds 2000 hours.