Preliminary Results of the 0-D Numerical Model for the Insert Region of a LaB6 Thermionic Hollow Cathode
by Oguz Korkmaz, Murat Celik

Thermionic hollow cathodes, which are used as ecient electron sources for ion engines and Hall thrusters both for propellent ionization and beam neutralization purposes, are essential components in electric propulsion systems for spacecrafts. Even though it has a simple geometry to build and is easy to operate, underlying physics of hollow cathode operation is not well understood and is still under investigation. Basically, the operation mechanism of hollow cathodes is the thermionic emission of electrons from an insert material that has low work function. To initiate electron emission, insert must be heated up to necessary temperatures typically between 1300 K and 1900 K with the use of an external heat source. After the creation of a dense plasma in the insert region, external heat source is turned o and the operation becomes self sustaining. The amount of heat, which is essential for the continuation of thermionic emission, is provided by the ions and the electrons coming from insert region plasma and recombining on the cathode wall. In this study, a 0D numerical model of hollow cathode has been developed in MATLAB enviroment in order to predict the plasma parameters such as electron temperature, plasma density in the insert region. The modeling results will be presented.