A model for the impregnated cathode emission behaviour under ion bombardment

The electron current emitted by a cathode in the saturation region decrease if the cathode is exposed to ion bombardment. The change in surface coverage with barium (oxide) is used in the model to describe the current behaviour. The steady state current reached (equilibrium current) depends on the gas pressure. The experimental results can be explained in terms of the model and the parameters are determined. The temperature dependence of the barium supply rate for an S-and M-type impregnated cathode are determined.