Fabrication and characterization of pressed Y2O3 doped Ba-W dispenser cathode

Abstract

A new kind of pressed Y₂O₃ doped Ba-W dispenser cathodes are prepared by a sol-gel method combined with high temperature sintering in dry hydrogen atmosphere. The results show that the growth of the grains is hampered by the pinning effect of Y₂O₃ distributing uniformly on the surfaces of tungsten particles, resulting in the formation of small grain size. It is found that Y₂O₃ improves the secondary electron emission property, i.e., the secondary emission yield increases with the increase of Y₂O₃ content in the samples. The maximum secondary emission yield δ_max of the cathode with 15% amount of Y₂O₃ can reach 2.92. Furthermore, the cathode shows a certain thermionic emission performance. The zero field emission current density J₀ of 4.18A/cm has reached at 1050^oC_b for this kind of cathode after being activated at 1200^oCb, which are much higher than that of rare earth oxide doped molybdenum (REO-Mo) cathode reported in the previous work.