CLASSE NEWS | 6 May 2014
Photoemission-based electron sources can provide extremely bright beams with sub-picosecond time resolution. Such sources enable applications such as ultrafast electron diffraction (UED), inverse compton scattering, electron cooling of hadron beams, polarized electron beams for colliders, and modern light sources based on free electron lasers or energy recovery linacs. The brightness of the beams provided by these sources is limited by the photocathode itself.
Using Monte Carlo based photoemission simulations; novel layered materials have been designed by researchers at CLASSE in order to optimize the photoemission properties to increase the brightness of electron beams. These engineered photocathode materials have been grown using Molecular Beam Epitaxy (MBE) and have demonstrated up to 50% increase in electron beam brightness. This work paves way to systematic theory based engineering of more complicated layered semiconductor materials to optimize photoemission.
This work was recently published in the Physical Review Letters, vol. 112, 097601 (2014). It was carried out under the supervision of Prof. Ivan Bazarov by graduate student Siddharth Karkare, undergraduate student Laurent Boulet and other team members. The group is now attempting to understand and explain photoemission from ab-initio principles with a motivation of developing photocathode engineered at the atomic level to enhance beam brightness by an order of magnitude.
CLASSE Researchers Design Novel Layered Materials to Increase Brightness of Electron Beams
Ab-initio atomic simulation of Cs atoms on GaAs(100) photocathode. The surface shows angstrom scale roughness which can affect photoemission.