Emission properties and back-bombardment for CeB₆ compared to LaB₆

The emission properties of CeB₆ compared to LaB₆ thermionic cathodes have been measured using an electrostatic DC gun. Obtaining knowledge of the emission properties is the first step in understanding the back-bombardment effect that limits wide usage of thermionic radio-frequency electron guns. The effect of back-bombardment electrons on CeB₆ compared to LaB₆ was studied using a numerical simulation model. The results show that for 6 μs pulse duration with input radio-frequency power of 8 MW, CeB₆ should experience 14% lower temperature increase and 21% lower current density rise compared to LaB₆. We conclude that CeB₆ has the potential to become the future replacement for LaB₆ thermionic cathodes in radio-frequency electron guns