Emission Performance of Graphene-Coated Ba-W Cathode

Emission performance of cathode depends largely on its surface state in terms of work function. By coating or doping appropriate materials on top of the cathode surface, cathode work function can be reduced and emission capability improved. We proposed and fabricated a new type of graphene-coated Ba-W cathode with the measured emission performance presented in this paper. The emission current of the cathode was measured with respect to voltage. And the equivalent surface work function of the cathode obtained using Schottky plot and Richardson plot, is as low as 1.16eV, and at least smaller than 1.56eV, which is significantly lower than that of B-type cathode. This low work function demonstrates the possibility for the cathode to be used as a kind of large current density or low working temperature cathode. However, uniformity and stability of the cathode still needs to be improved, for it was found that only a small part of the surface has participated in the electron emission in low temperature regions.