Speaker
Description
Next-generation x-ray free-electron lasers will push ultrafast science to ultra-high repetition rates, demanding flexible upstream control that adapts electron-beam properties in real time. The photoinjector laser (PIL), defining the electron beam's initial phase-space, represents a powerful and largely untapped actuator. We present results from a coordinated campaign at LCLS-II demonstrating complementary regimes of programmable PIL ultraviolet pulse shaping. In the first, engineered flat-top UV profiles sustain higher peak currents over longer durations while maintaining low emittance, enhancing FEL gain. In the second, multi-peaked UV modulations imprint structure on the electron bunch, producing x-ray emission profiles with similar temporal features. Together, these results show that a single programmable architecture—combining dispersion-controlled nonlinear synthesis** with spatial-light-modulator spectral shaping—serves dual roles: optimizing beam quality for maximum FEL performance and enabling on-demand x-ray pulse structuring. This source-level approach establishes a foundation for adaptive and autonomous operation of high-repetition-rate light sources.
Footnotes
Zhou et al., PRAB 24, 073401 (2021)
Zhang et al., arXiv:2601.03580 (2026)
Hirschman et al., arXiv:2603.15996 (2026)
**Lemons et al., Ultrafast Sci. 5, 0112 (2025)
Funding Agency
Work supported by DOE BES under DE-AC02-76SF00515, DE-SC0022559, DE-FOA-0002859, DE-FG02-86ER13491; NSF 2231334, 2431903, 2436343; AFOSR FA9550-23-1-0409.
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