Speaker
Description
We investigate attosecond spike formation in an x-ray free-electron laser driven by sign-reversing chirped undulator tapering. Time-dependent three-dimensional simulations with Athos-like soft-x-ray parameters reveal a characteristic evolution of the slice-resolved bunching across the taper reversal: localised bunching surviving before the reversal provides a coherent starting point for delayed amplification into fresh slices. We organise the underlying dynamics into three stages – bunching build-up, bulk suppression with localised bunching memory, and reversal-triggered re-amplification – and show that the different behaviour obtained with a sawtooth-shaped modulation is consistent with the same dynamical picture. The individual spikes in the resulting attosecond pulse train reach FWHM durations of about 200–300 as, with peak powers in the tens-of-gigawatts range, while the reference configuration without chirp-based tapering produces a multi-femtosecond SASE pulse.
Funding Agency
No external funding to declare.
| I have read and accept the Privacy Policy Statement | Yes |
|---|