Nano-graphite cold cathodes for electric solar wind sail

The nanographite (NG) films consisting of tiny graphite crystallites (nanowalls) are produced by carbon condensation from methane-hydrogen gas mixture activated by a direct current discharge. High aspect ratio and structural features of the NG crystallites provides efficient field electron emission (FE). Applicability and performance of the NG films in an electron gun (E-gun) of a solar wind thruster system with an electric sail (E-sail) is tested. The long-term tests are demonstrated suitability of E-gun assembly with the NG cathodes for the real space missions. The results of the tests are analyzed and physical mechanisms of the cathode aging and practical methods for improvement performance of the E-gun are proposed.