Andonian, G.
(Gerard Andonian)

THPOS56 VISA IB: Ultra-High Bandwidth, High Gain SASE FEL
Gerard Andonian, Ronald Barkley Agustsson, Alex Murokh, Claudio Pellegrini, Sven Reiche, James B Rosenzweig, Gil Travish (UCLA, Los Angeles, California), Marcus Babzien, Ilan Ben-Zvi, Jung Yun Huang, Vladimir N. Litvinenko, Vitaly Yakimenko (BNL, Upton, Long Island, New York), Ilario Boscolo, S. Cialdi, Alessandro Flacco (INFN Milano, Milano), Massimo Ferrario, Luigi Palumbo, C. Vicario (INFN/LNF, Frascati (Roma))

The results of a high energy-spread SASE FEL experiment, the intermediary experiment linking the VISA I and VISA II projects, are presented. A highly chirped beam (~1.7%) was transported without correction of longitudinal aberrations in the ATF dogleg, and injected into the VISA undulator. The output FEL radiation displayed an uncharacteristicly large bandwidth (~11%) with extremely stable lasing and measured energy of about 2 microJoules. Start-to-end simulations reproduce key features of the measured results and provide an insight into the mechanisms giving rise to such a high bandwidth. These analyses are described as they relate to important considerations for the VISA II experiment.