Design and Analysis of the Heater Region of a Low Current Hollow Cathode
by Ali Enes Ozturk, Oguz Korkmaz, Murat Celik

In Kauman type ion engines and Hall thrusters, the electron-impact ionization is the main ionization mechanism; therefore these thrusters require electron sources that provide the necessary electrons for the ionization process. Hollow cathodes are the devices that are most commonly used for providing the needed electrons for ionization in such electric thrusters as well as for providing electrons to prevent spacecraft from charging due to the electric thruster ion beam. Hollow cathodes used in modern electric propulsion systems usually have a thin, long, hollow cylindrical conductor pipe in which an insert material with low work function is placed. The heating of the insert material causes increased electron emission from the surface to the hollow inner part of the cathode tube where a propellant flow is supplied. During steady state operation, the plasma generated inside the cathode tube provides a self-heating mechanism to keep the thermionic emission from the surface at a steady rate. However, in order for the cathode discharge to begin, an external heating mechanism has to be used. In this study, the thermal analysis around the heater region is made by using commercial FEA software. Results of the detailed 2D and 3D analysis with radiation and joule heating are presented.