CALCIUM SURFACE DIFFUSION IN IMPREGNATED CATHODE ENHANCED BY OXYGEN
氧作用下浸渍钡钨阴极中钙的强化表面扩散

The Ca behavior of an impregnated cathode is studied with enhanced diffusion of Ca to the cathode surface induced by low pressure oxygen, and the changes of surface composition are analysed with AES and the method of surface accumulation. The experimental results show that: (1) a significant part of Ca exist in metallic form in the near surface region of the active material in the pores of impregnated cathode ; (2) the diffusion rate of Ca to the surface is proportional to the O2 exposure quantity and the cathode temperature, the activation energy of Ca surface(?)fusion enhanced by O2 is about 1.34eV; (3) one of the reasons of emission decay under oxygen effect may be considered due to the increase of calcium oxide on the cathode surface, and the one of principal mechanisms of the reactivation is the high temperature cleaning process of the Ca by evaporation.