Overview of SwissFEL dual-photocathode laser capabilities and perspectives for exotic FEL modes

Bettoni, S.; Cavalieri, Adrian L.; Dax, A.; Divall, E. J.; Hauri, Christoph P.; Hunziker, S.; Huppert, Martin; Kaiser, M.; Paraliev, M.; Sydlo, Cezary; Vicario, C.; Trisorio, A.

doi:10.1017/hpl.2021.36

Cited by 4 publications

(2 citation statements)

References 34 publications

(33 reference statements)

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“…In table I, the main parameters of the PC and LES at the photocathode are reported. Both the lasers consist of a low-noise Yb-based oscillator and a diode-pumped Yb:CaF2 regenerative amplifier running at 100 Hz [10]. At SwissFEL, an emittance of several hundred nm is required for the full bunch to radiate at the shortest wav elengt h (1 Å) [1].…”

Section: Methodsmentioning

confidence: 99%

Demonstration of two-color x-ray FEL by laser emittance spoiler

Vicario¹,

Bettoni²,

Dax³

et al. 2023

X-Ray Free-Electron Lasers: Advances in Source Development and Instrumentation VI

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Two-color is an emerging mode of operation in x-ray Free Electron Laser (FEL) having the potential to expand the pump and probe experiments toward fs temporal resolution and to site-selective spectroscopy. A novel and quick to setup method for two-color x-ray generation is presented here. The approach is experimentally demonstrated at the hard x-ray branch of SwissFEL (Aramis) using a laser emittance spoiler(LES). A short laser pulse is overlapped at the peak of the primary photocathode laser causing a local increase of the electron bunch emittance. In this configuration, the x-ray FEL emission occurs only for the two unspoiled parts of the bunch. Due to the fact that the electron bunch acquires an energy chirp along the acceleration, the spoiled beam produces two x-ray pulses of individual duration of few tens of fs having 1% photon energy separation and a time delay controllable up to 100 fs. Different from other techniques, the present method relies on the standard FEL configuration and it does not require a dedicated accelerator and undulator setting. With the LES, we achieved high efficiency, high energy and spectral stability paired to an independent control of the duration and of the relative intensity of the two colors. The LES enables shot-to-shot switching between one and two-color FEL and further, it is compatible with high repetition-rate FELs, as it is not associated to electron beam losses such as in other two-color methods.

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Section: Methodsmentioning

confidence: 99%

Demonstration of two-color x-ray FEL by laser emittance spoiler

Vicario¹,

Bettoni²,

Dax³

et al. 2023

X-Ray Free-Electron Lasers: Advances in Source Development and Instrumentation VI

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show abstract

“…The performance of SwissFEL at Paul Scherrer Institute is very sensitive to the beam profile and pointing stability of the photocathode laser. High-energy femtosecond deep UV laser damages optics in the beam path and the beam becomes non-Gaussian in spatial profile, which can be improved by Fourier filtering [1]. The filtering properties are strongly dependent on the incoming beam pointing and the focal position, creating a five-dimensional parameter space for alignment, which currently needs to be manually adjusted.…”

Section: Motivationmentioning

confidence: 99%