Preparation of Scandium Dispenser Cathode by Microwave Sintering and It’s Electron Emission Property

Abstract:

In this paper, uniform scandia doped tungsten powder was prepared by sol-gel method combined with reduction process, and then the scandia doped impregnated cathode was successfully prepared by microwave sintering. The characteristics of Sc-doped tungsten powder, the microstructure of cathode sponge matrix, the emission properties, and the surface behavior of the active substance were analyzed. The result shows that the scandia doped tungsten powder has the average size of around 1μm and Sc element was uniformly distributed. The morphology of the sponge skeleton have spherical shape, the pore distribution was uniform, the average pore diameter is about 0.46 μm, and scandia is evenly distributed in the matrix. The cathode prepared by the microwave sintering method exhibited good emission properties, e.g., the current density of this cathode reached 137.59 A/cm2 at 950 ℃b, and the emission slope is 1.431. The atomic ratio of Ba:Sc:O on the cathode surface is 1.8:1:2.2 after activation, and a amount of nanoparticles are present on the cathode surface , which promotes emission of the cathode.

Key words:tungsten; scandate dispenser cathode; thermionic emission; microwave sintering;