Studies on the pressed yttrium oxide-tungsten matrix as a possible dispenser cathode material

Abstract

Yttrium oxide was chosen as the secondary emission substance based on calculation results through first principle theory method. A new kind of pressed yttrium oxide-tungsten matrix 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 between the 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 δmax 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/cm2 has reached at 1050 °Cb for this kind of cathode after being activated at 1200 °Cb, which are much higher than that of rare earth oxide doped molybdenum (REO-Mo) cathode reported in the previous work.