Electron beam energy spectrum measurements at Vanderbilt FEL

(MO-3-28)

B. Feng, R.C. Grant, R. Ardrey and W.E. Gabella  

Vanderbilt University

The electron beam energy spectrum strongly affects the free electron laser efficiency, especially in the regime of large slippage between the electron bunch and the optical pulse. A fast electron energy spectrometer has been built using a photodiode array measuring the backward optical transition radiation from an aluminum foil. We present the measurements of time resolved electron beam energy spectrum on the Mark III linear accelerator at Vanderbilt University, while lasing in the 2-9 micron range.