High current density cathodes - An update

This paper describes recent developments and test results in the field of high current density thermionic cathodes. In all cases the enhanced performance (8 to 16 A/cm²) has been achieved by a separate treatment of the emissive surface (low work function) and of the bulk of the matrix (to maintain a sufficient rate of active barium compound generation). Because of a diversity of specific requirements, different embodiments of such cathodes exist, i.e., alloy-overcoated, mixed metal matrix, reservoir-type cathodes, etc.