The heating properties of LaB6 and CeB6 cathodes are investigated against the Back Bombardment
(BB) effect in thermionic RF guns by using numerical calculations of the stopping range and
the heat power deposited inside the cathode materials. Then, the change in the cathode temperature
and the corresponding change in the current density during the 5.5 µs macropulse are determined
by solving two differential equations. The simulation results show that the change in the current
density during the macropulse for LaB6 was two times higher than that for CeB6; hence, the effect
of the BB electrons in CeB6 is less than it is for LaB6