Demonstration of Transverse-To-Longitudinal Emittance Exchange at the Fermilab Photoinjector

Phase space manipulation techniques with two degrees of freedom could be essential to the enhancement of the performance of next generation accelerators such as high energy colliders and accelerator‐based light sources. At the Fermilab A0 Photoinjector, a proof‐of‐principle experiment to demonstrate the exchange of the transverse and longitudinal emittance is ongoing. The emittance exchange (EEX) beamline consists of a 3.9 GHz normal conducting deflecting mode cavity positioned between two doglegs as proposed by Kim and Sessler. The experiment is performed using electron bunches with charge of 250 pC and energy of 14.3 MeV. The incoming electron beam has transverse emittance of 2–4 mm mrad and longitudinal emittance of 10–14 mm mrad. After the EEX the measured horizonal emittance is blown up to 13–15 mm mrad while the measured vertical emittance (Non EEX plane) stays the same. At the same time the longitudinal emittance is reduced to 7–9 mm mrad as measued by the current longitudinal diagnostic tools. A linear optics model is established using the beam matrix calculated and measured. A first order simulation based on this model is performed to compare to our experiment results for both EEX measurement and the phase space manipulation experiment.