Endurance Tests of Graphite Orificed Hollow Cathodes

This paper describes the present status of endurance tests of graphite orificed hollow cathodes at the Japan Aerospace Exploration Agency (JAXA). Discharge and neutralizer cathodes have been developed for JAXA's xenon ion engines. In order to achieve long life with stable performance, the keeper disk, orifice plate, and cathode tube in these cathodes are made of high-density graphite. An endurance test of the discharge cathode was started in March 2006 in a discharge chamber without beam extraction. Cumulative operation time reached 25,800 hours in August 2009 and there have been no signs of performance deterioration so far. An endurance test of the neutralizer cathode was started in June 2008 and has accumulated 9,300 hours of operation.