Study of surface nano-particles of scandate cathodes

Scandate cathode exhibits the highest emission property among all the thermionic cathodes. Scanadia Doped Dispenser cathode (SDD cathode) is one of the promising cathodes due to its good emission property and reproducibility. The impacts of local electric field enhancement on emission capability of cathode have be considered by applying the actions of Schottky effect and electric field on semiconductor model presented by D. Wright[1]. The calculation results show that the current densities near the spherical nanoparticles are less than 2 times higher than that of the surrounding area. After operating with high current densities at high temperatures for a relative long time, this function was reduced due to the loss of the nanoparticles.