The ALPHA-X beam line : toward a compact FEL

Recent progress in developing laser-plasma accelerators is raising the possibility of a compact coherent radiation source that could be housed in a medium-sized university department. Beam properties from laser-plasma accelerators have been traditionally considered as not being of sufficient quality to produce amplification. Our work shows that this is not the case. Here we present a study of the beam characteristics of a laser-plasma accelerator. We also highlight the latest results on the ALPHA-X compact FEL. We show how the beam properties of the ALPHA-X beam line have been optimized in order to drive a FEL. We discuss the implementation of a focussing system consisting of a triplet of permanent magnet quadrupoles and a triplet of electromagnetic quadrupoles. The design of these devices has been carried out using the GPT (General Particle Tracer*) code, which considers space charge effects and allows a realistic estimate of electron beam properties along the beam line. The latest measurements of energy spread and emittance will be presented. Currently we have measured energy spreads less than 0.7% and, using a pepper pot, put an upper limit on the emittance of 5 pi mm mrad