One-Dimensional Hollow Cathode Model

Hollow cathodes with barium-rich inserts are used in ion engines as electron sources both in the discharge chamber and to neutralize the ion beam. Future deep space missions will require hollow cathode lifetimes in excessof the 28,000 h demonstrated during the International Space Station plasma contactor hollow cathode life test. A hollow cathode model is developed based on the observation that xenon ion mobility is diffusion limited due to resonant charge exchange reactions. Application of the model to the orifice region shows that the resultant ion generation profile correlates with previously reported orifice erosion. Modeling of the insert region shows that vapor-phase barium atoms are ionized almost immediately and electric fields accelerate the ions upstream from the "emission zone".

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