Fabrication and thermionic emission properties of lanthanum carbide doped tungsten cathodes

A new type of thermionic cathode, lanthanum carbide doped tungsten cathode, has been fabricated through a spark plasma sintering method by using the mixed powders of lanthanum carbide and tungsten. Lanthanum carbide powder was prepared by a levitation melting method in vacuum. The thermionic emission properties have been investigated. It is found that the concentration of lanthanum carbide has a significant influence on the emission properties of the cathodes. The emission current density of the tungsten cathode at 1400 degrees C-b was increased dramatically from 1.09 to 3.12 A/cm(2) with the increase of concentration of lanthanum carbide from 3.5 to 10 wt%. The emission mechanism of the cathode has been discussed. (C) 2014 Elsevier B.V. All rights reserved.