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TY - UNPB AU - MacArthur, J.P. ED - Schaa, Volker R.W. ED - Decking, Winfried ED - Sinn, Harald ED - Geloni, Gianluca ED - Schreiber, Siegfried ED - Marx, Michaela TI - Microbunch Rotation and Coherent Undulator Radiation from a Kicked Electron Beam J2 - Proc. of FEL2019, Hamburg, Germany, 26-30 August 2019 CY - Hamburg, Germany T2 - Free Electron Laser Conference T3 - 39 LA - english AB - Microbunches form perpendicular to the electron travel direction, and the conventional understanding is that they shear rather than rotate in response to a transverse kick, locking FEL facilities into a single-user operating mode. We show that microbunches rotate toward the new direction of travel if the electron beam is kicked and defocused. We provide evidence that microbunch rotation explains the unexpectedly large amount of off-axis radiation observed during experiments at the Linac Coherent Light Source. We demonstrate that LCLS can be multiplexed into at least three soft X-ray beams using this principle. Finally, we report on a more sophisticated scheme of offset quadrupoles that was used to produce two distinct hard X-ray spots at LCLS. PB - JACoW Publishing CP - Geneva, Switzerland ER -