Studies of the Influence of ZrH 2 Addition to the Impregnant on the Performance of Yttrium Oxide–Tungsten Matrix Ba Dispenser Cathodes

The cathode in the magnetron should have good secondary emission property and a certain thermionic property. In this article, ZrH2 was added as an activator to obtain rare earth-doped tungsten matrix impregnated cathode to improve the emission property. Cathodes with ZrH2 (Y15-411-Zr cathode) or without ZrH2 (Y15-411 cathode) were prepared by a spray drying method combined with high-temperature sintering in dry hydrogen atmosphere. The emission properties and emission mechanism have been studied. The results showed that thermionic emission performance and secondary emission performance of Y15-411-Zr cathode are 3.4 times and 1.2 times higher than those of Y15-411 cathode, respectively. With the addition of ZrH2, yttrium was produced during activating process, which contributed to the better emission properties of Y15-411-Zr cathode. Furthermore, the work function of barium and oxygen adsorbed on yttrium oxide and yttrium surface was calculated using the first principle. The results showed that the lowest work function of Ba-O absorbed on Y2O3 and Y is 1.9 and 1.6 eV, respectively.