Abstract
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.
Highlights
High-performance photocathodes have become the enabling technology for advanced light sources and accelerators, such as x-ray free electron laser, energy recovery linac, and ultrafast electron diffraction [1,2,3]
The results indicate that the Quantum efficiency (QE) increases with the K2CsSb photocathode thickness and approaches saturation at approximately 20 nm
It needs to be mentioned that the introduction of surface plasmon polaritons (SPPs) brings some potential risk factors that may cause the degradation of the overall emittance of the electron beam emitted from the cathode, such as the introduction of plasmonic near field (PNF) and distortions of the applied accelerating field caused by the nanopattern structure
Summary
High-performance photocathodes have become the enabling technology for advanced light sources and accelerators, such as x-ray free electron laser, energy recovery linac, and ultrafast electron diffraction [1,2,3]. Surface plasmon polaritons (SPPs) have been used in various fields because of their unique characteristics, such as exceptional absorption and local near field enhancement [12,13,14] These features have the potential to improve the performance of photocathodes. In order to improve the QE and obtain low thermal emittance, a nanopatterned K2CsSb photocathode was designed to excite the SPPs, enhancing the effective absorption of the incident light and artificially modulating the initial photoelectron distribution in the photocathode. The modification of the Monte Carlo model to simulate the photoemission processes of the K2CsSb photocathode with SPPs is presented in Sec. III B. The effect of tuning the incident laser photon energy on the performance of the plasmon-enhanced K2CsSb photocathode is elucidated in Sec. III D.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
