Hollow cathode chemical modelling

In this paper the state of hollow cathode life time modelling at the University of Southampton will be reported. Two models have been developed: one for BaO depletion from the hollow cathode insert and another for low work function compounds deposition and desorption. The model developed to predict BaO depletion from hollow cathode insert will be presented together with some comparison between experimental and numerical data to prove its validity.A model for low work function compounds deposition and desorption will also be presented. This model will be used to simulate the NSTAR cathode showing a very conservative estimate of the cathode life due to conservative character of the hypotheses made in the model development and due to the chosen criteria for the end of life