Preliminary Characterization of a LaB 6 Hollow Cathode for Low-Power Hall Effect Thrusters IEPC-2013-137 Presented at the 33 rd International Electric Propulsion Conference, The George Washington University, Washington, D.C., USA October 6–10, 2013 R. Albertoni, * M. Andrenucci † Alta SpA, Ospedaletto, Pisa, 56121, Italy D. Pedrini, ‡ F. Paganucci § University of Pisa, Pisa, 56126, Italy An experimental investigation of the operating characteristics of a heaterless LaB 6 hol- low cathode was performed to examine low-current and low flow rate operation. The cathode has been continuously operated at Xe mass flow rates between 0.08 mg/s and 1 mg/s and discharge currents ranging from 0.5 to 3 A in diode mode for two different ori- fice diameters. The minimum power consumption was of about 25 W while the minimum mass flow rate required for spot-mode emission was approximately 0.08 mg/s Xe. The experimental data gathered during the test campaign were used to refine the theoretical model developed by Alta for the performance assessment of rare-earth thermionic hollow cathodes. Nomenclature AR = Aspect ratio D = Diameter, m f = Frequency, s -1 L = Length, m R = Radius, m Subscripts o = Orifice region e = Emitter region k = Keeper I. Introduction W hile state-of-the-art (SoA) electric propulsion (EP) systems provide remarkable mass and cost advan- tages with respect to chemical thrusters for both station-keeping and attitude control missions, a need remains for performance improvement in sub-kilowatt propulsion systems for small satellites. 1 In this con- text, the cathode plays a fundamental role in the overall performance of low power (< 500 W) ion and Hall thrusters. As a matter of fact, Patterson 1 reported that a typical impregnated cathode/neutralizer for a 100 W-class ion thruster could degrade the thrust efficiency by approximately 20% and reduce the specific im- pulse by as much as 2000 s. In addition, since typical missions for ion and Hall thrusters require thousands of hours of operation, cathodes lifetime becomes a crucial issue especially for attitude-control operations where * Research Engineer, r.albertoni@alta-space.com. † President, m.andrenucci@alta-space.com ‡ PhD Student, Department of Civil and Industrial Engineering, daniela.pedrini@for.unipi.it § Associate Professor, Department of Civil and Industrial Engineering, f.paganucci@ing.unipi.it 1 The 33 rd International Electric Propulsion Conference, The George Washington University, USA October 6–10, 2013