Abstract:
The goal of the Femtoslicing project at the ALS is to
provide 100-200 fs long pulses of soft and hard x-rays with
moderate flux and with a repition rate of 10-40 kHz for
experiments concerning ultrafast dynamics in solid state
physics, chemistry and biology. The femtoslicing principle
employs a femtosecond laser beam to interact resonantly (FEL
interaction) with the electron beam in the ALS. The induced
energy spread over the femtosecond duration is converted to
a transverse displacement by exploiting the dispersion of
the storage ring. The displaced femtosecond electron pulse
then radiates and produces femtosecond synchrotron
radiation. To achieve the necessary spatial separation of
the energy modulated slice from the rest of the bunch, a
sizeable local vertical dispersion bump in the undulator
used as radiator is required. This presents challenges in
terms of the nonlinear dynamics and control of the vertical
emittance.