Development of a Low-Work-Function Thermionic Cathode by Coating with LaB6 and Carbide

A novel electron gun with lanthanum hexaboride (LaB
₆
) thermionic cathodes with relatively low work functions is being developed by coating the metal surface with another When operated under thermionic emission mode, this tool provides both high brightness and high beam current simultaneously, has a long lifetime, and offers good stability during operation. Herein, we describe the basic design concept for a novel LaB
₆
cathode involving infiltration of a carbide solution. Moreover, we experimentally measured the thermionic-emission-mode work function of the rhenium surface modified with a LaB
₆
single-crystal powder and carbide solution.