CeB6: Emission Performance and Uniformity Compared With LaB6 for Thermionic RF Guns

Thermionic emission performance from single crystals of CeB
₆
and LaB
₆
was investigated at different operational loads using a test machine, in order to consider CeB
₆
as a cathode for thermionic RF guns in the future applications. To evaluate cathode quality and uniformity for long lifetime applications, Miram curves in conjunction with their associated practical work function distribution (PWFD) were applied to the thermionic emission results. The analysis of the PWFD plot revealed that the variation of the peak in the work function and full-width at half-maximum for CeB
₆
is very close to that of LaB
₆
. This suggests that emission performance, uniformity, and expected operational lifetime of a CeB
₆
cathode are comparable with LaB
₆
cathodes. In addition, previous simulation results of the back bombardment (BB) effect on CeB
₆
and LaB
₆
emphasized that CeB
₆
presents less sensitivity to BB electrons compared with LaB
₆
at a 5.5-μs pulse duration and 8-MW RF power. This gives CeB
₆
the potential to replace LaB
₆
as a thermionic cathode for an RF gun. A complete analysis of the cathode emission performance and PWFD at different operational loads for CeB
₆
prior to a prospective real test is presented.