Upgrades of beam diagnostics with application to emittance-exchange experiments

Abstract

The possibility of using electron-beam phase-space manipulations to support a free-electron laser accelerator design optimization has motivated our research. An ongoing program demonstrating the exchange of transverse horizontal and longitudinal emittances at the Fermilab A0 photoinjector has benefited recently from the upgrade of several of the key diagnostics stations. Accurate measurements of these properties upstream and downstream of the exchanger beam line are needed. Improvements in the screen resolution term and reduced impact of the optical system’s depth of focus by using YAG:Ce single crystals normal to the beam direction will be described. The requirement to measure small energy spreads (<10 keV) in the spectrometer and the exchange process which resulted in bunch lengths less than 800 fs led to other diagnostics performance adjustments and upgrades as well. Application of these diagnostics in demonstrating the exchange of transverse (x) and longitudinal phase spaces is also reported.