A comprehensive study of pulsed high-current secondary electron emission cathode

Abstract

Pulsed secondary electron multipacting (SEM) cathodes with channel-type structures have been developed. The electron emission performance of these cathodes was investigated using theoretical and particle-in-cell simulation methods. The results revealed that the electrical conductivity of the channel wall material is crucial to the performance of the cathodes. Materials with low conductivity cause the SEM process in the multipacting channel to stop quickly due to the positive charges deposited on the channel wall. These positive space charges, generated by the SEM process, create a space-charge field that reduces the impact energy of electrons on the channel wall, thereby decreasing the secondary electron emission yield. Consequently, materials with high electrical conductivity and high secondary electron emission yield, such as SnO2, are advantageous for the SEM process, leading to stable current output from the cathodes with high current density. For a SnO2 cathode with three multipacting channels, an output current density of 242 A/cm2 was achieved.