Fabrication and thermionic emission properties of lanthanum carbide doped tungsten cathodes

• A new cathode, LaCx doped W cathode, is prepared by a powder metallurgy method.
• The cathode with 10 wt% LaCx exhibits a current density of 3.12 A/cm2 at 1400 °Cb.
• The j0 of this cathode meets the requirement for magnetron application.
• High temperature carburization and activation processes are eliminated.

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 °Cb was increased dramatically from 1.09 to 3.12 A/cm2 with the increase of concentration of lanthanum carbide from 3.5 to 10 wt%. The emission mechanism of the cathode has been discussed.