Longitudinal phase space tomography at the SLAC gun test facility and the BNL DUV-FEL

The Gun Test Facility and the accelerator at the DUV-FEL facility are operated as sources for high brightness electron beams; the first for the Linac Coherent Light Source project and the latter driving an FEL using High Gain Harmonic Generation in the UV. For both accelerators, projections of the longitudinal phase space on the energy coordinate were obtained by varying the phase of an accelerating structure after the gun and measured with a downstream spectrometer dipole. Using an algebraic reconstruction technique, the longitudinal phase space at the entrance to the varied accelerating structure could be reconstructed over a large range of charge from 15 to 600 pC.