Lanthanum Hexaboride Hollow Cathode for the Asteroid Redirect Robotic Mission 12.5 kW Hall Thruster

Abstract

A lanthanum hexaboride hollow cathode has been developed for use in the 12.5-kW Hall thruster under development for the proposed Asteroid Redirect Robotic Mission (ARRM). This cathode is larger than the original version developed at JPL that has operated successfully for years in the H6 Hall thruster, and has calculated lifetimes of 100 kh at 40 A of discharge current and over 50 kh at 50 A of discharge current. A 1.5-cm-dia. laboratory prototype of this cathode has been designed and built for testing with the Hall thruster under development for ARRM. This cathode has been successfully operated in our test facilities over the full operating gas flow rate and discharge current required for the ARRM mission concept.