Effect of Surface Features on Emission Properties of Impregnated Scandate Dispenser Cathode

The scandate dispenser cathode has a clear advantage in current emission density but lacks emission uniformity. In this work, volt-ampere characteristics of impregnated scandate cathodes are examined at 1000, 1050, and 1100
${}^{\circ} \mathbf{C}$
, respectively, in order to study the changes in the emission characteristics of the cathode after surface ion bombardment. After surface treatment, the Richardson work function decreased from 1.33 to 1.19
$e$
V, and its Richardson constant dropped from 0.024 to 0.017
$\mathrm{A}/(\text{cm}^{2}*\deg^{2})$
. The surface of the cathode is less rough than before ion treatment, as evidenced by the atomic force microscope image. More importantly, the cathode does not exhibit an abnormal Schottky effect after ion bombardment on the surface, which indicates that surface treatment can improve the emission uniformity of scandate cathodes.