Growth and Characterisation of Thin Film and Alkali Metal Photocathodes for the Generation of High-Brightness Electron Beams
Student: Mekhna Venu
Supervisor: Carsten P Welsch (UoL)
Institution: University of Liverpool
The highest levels of electron beam quality are obtained using a photoemission based electron source or photoinjector, which is a photocathode electron source emitting into an accelerating electric field. Alkali metal and thin film photocathodes are ideal candidates for these applications as they demonstrate high levels of quantum efficiency (QE) and good operational lifetime, thus permitting long uninterrupted periods of user exploitation. The high levels of QE gives additional headroom in respect of illumination laser power to facilitate transverse and longitudinal laser pulse shaping, and thus maximise the electron beam brightness and quality.
This PhD project will focus on development of techniques to manufacture high-performance thin-film photocathode electron sources for particle accelerators, modifying and expanding the deposition equipment and processes as necessary. The intention is to identify the optimum materials and preparation techniques to achieve the highest levels of electron beam brightness, with the lowest intrinsic emittance and the longest operational lifetime. The project will continue the development and exploitation of the Transverse Energy Spread Spectrometer (TESS) for the characterisation of novel photocathode electron source materials.
In the first year of the project, the student will familiarise themself with the existing surface analysis and photocathode growth equipment, and TESS to characterise photocathode electron sources, and contribute to the commissioning of the new alkali metal photocathode growth facility which has been part-funded by the Cockcroft Institute.
In subsequent years, they will focus on the growth and characterisation of photocathode sources with different compositions, seeking an optimum deposition solution, identifying new/improved electron sources, and publishing results. The results are of high importance for many particle accelerator and light source projects and you will automatically develop an international contact network as part of your project. The photocathodes developed in this project may then be utilised in the CLARA accelerator, and the project includes the opportunity to join the accelerator operations teams to characterise their performance and gain hands-on experience at a cutting edge research facility.
The project will take place predominantly at Daresbury Laboratory, mostly involving laboratory-based studies of photoemissive materials in our state-of-the-art Vacuum Interfaces and Surface Technologies for Accelerators (VISTA) laboratory. There will also be the opportunity to use other research facilities within the lab to further characterise these materials to investigate ultimate beam brightness achievable.