Monte Carlo simulations of electron photoemission from plasmon-enhanced bialkali photocathode

Photocathodes based on bialkali antimonides have great potential in the field of high-brightness electron sources. In this paper, the influence of incident light absorption on the performance of ${\mathrm{K}}_{2}\mathrm{CsSb}$ photocathodes was studied using Monte Carlo simulations. The surface plasmon polaritons (SPPs) were first introduced into ${\mathrm{K}}_{2}\mathrm{CsSb}$ photocathodes employing a nanopattern structure to improve the effective absorption of incident light and adjust the initial distribution of the photoelectrons. To evaluate the effect of SPPs on the photocathode performance, photoemission from such photocathodes was modeled using Monte Carlo simulations. Simulations show the quantum efficiency of the ${\mathrm{K}}_{2}\mathrm{CsSb}$ photocathode increases by 2--3 times that of the photocathode without SPPs. Moreover, the thermal emittance of the photocathode remains unchanged. These results are crucial to the future development of high-brightness electron beams.