Speaker
Description
Nanostructured cathodes provide local electric field enhancement in the ultraviolet regime, which increases photon absorptance and the resulting photocurrent density. We present a photoemission and beam dynamics study of a nanostructured copper photocathode for electron gun applications. Electromagnetic simulations are used to determine the spatial distribution of the photocurrent density on the cathode surface. Beam dynamics simulation results are presented, featuring the phase-space modification induced by the surface structure, compared to the case of a flat photocathode. The results show that the nanostructured surface yields higher normalized emittance and mean transverse energy relative to flat copper. The modified geometry produces an asymmetric particle distribution with a pronounced tail in the longitudinal phase space. Schottky correction and space charge effects are included in the analysis. Approaches to reduce the associated computational cost are also discussed.
Funding Agency
Work is funded by the German Ministry of Research (BMBF) under
contract 005K2022
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