A Measurement of High Gain Sase Fel Induced Electron Beam Micro-bunching Using Coherent Transition Radiation

Coherent transition radiation (CTR) was used to study the longitudinal modulations of an electron beam exiting the UCLA/LANL high gain SASE FEL. The induced longitudinal micro-bunching of the electron beam at the exit of the undulator was measured with a frequency domain technique using the CTR emitted when this beam strikes a thin conducting foil. Formalisms for both CTR and SASE theories are related using the simulation code GINGER in which the SASE FEL gain of the output radiation and the micro-bunching of the electron beam are given. Experimental results from the CTR measurement will show the limit of standard transition radiation (TR) theory is being approached and new analysis is needed.