MOZD3
Stanford University, Stanford, California, USA
SLAC, Menlo Park, California, USA
We report the generation of GW-level attosecond pump/probe pulse pairs with tunable sub-femtosecond delays at the Linac Coherent Light Source (LCLS). The attosecond 370 eV pump pulse is first generated via the Enhanced Self-Amplified Spontaneous Emission (ESASE) method, then the attosecond 740 eV probe pulse is produced by re-amplifying the electron beam microbunching after the magnetic chicane. Due to the harmonic amplification, the minimal delay between pump-probe pulse pairs (limited by slippage between the light field and the electron bunch) can be shorter than 1 femtosecond. We use the angular streaking technique to measure temporal delays between pump/probe pulse pairs at multiple beamline configurations. When the delay chicane is turned off, the averaged delay is increased by ~150 attoseconds by adding one undulator module for probe pulses. Long delays can be set up by turning the delay chicane on. These experimental results are in agreement with start-to-end XFEL simulations. Looking toward future experiments, our sub-femtosecond pump/probe technique can be applied to observe electronic charge dynamics in molecular systems.
FRXD5
SLAC, Menlo Park, California, USA
With the goal of improving emittance and longitudinal phase space of the electron beam, we consider nonlinear shaping of the temporal laser profile at the cathode. The operational Ultraviolet (UV) optics installed at the LCLS and LCLS-II currently produce Gaussian shaped pulses. Our simulations show the potential to reduce emittance and increase peak brightness when comparing nonlinear UV laser shapes on the cathode to baseline Gaussian pulses at the cathode.