Numerical Simulations of Early-Stage Dynamics of Electron Bunches Emitted from Plasmonic Photocathodes

TL;DR

This paper presents numerical simulations of the initial electron emission and beam dynamics from plasmonic photocathodes, highlighting their potential for structured beam formation and enhanced quantum efficiency in compact accelerators.

Contribution

It introduces a detailed simulation framework for early-stage electron emission from plasmonic photocathodes, combining emission modeling with beam dynamics analysis.

Findings

Enhanced quantum efficiency observed in plasmonic cathodes.

Potential for structured beam formation with transversely-separated beamlets.

Insights into imaging of cathode patterns after acceleration.

Abstract

High-brightness electron sources are a key ingredient to the development of compact accelerator-based light sources. The electron sources are commonly based on (linear) photoemission process where a laser pulse with proper wavelength impinges on the surface of a metallic or semiconductor photocathode. Very recently, the use of plasmonic cathodes - cathodes with a nano-patterned surface - have demonstrated great enhancement in quantum efficiencies (Li et al., 2013 [1]). Alternatively, this type of photocathodes could support the formation of structured beams composed of transversely-separated beamlets. In this paper we discuss numerical simulations of the early-stage beam dynamics of the emission process from plasmonic cathodes carried out using the Warp (Friedman et al., 2014 [2]) framework. The model is used to investigate the properties of beams emitted from these photocathode and subsequently combined with particle-in-cell simulations to explore the imaging of cathode pattern after acceleration in a radiofrequency gun.