Demonstration of Large Bandwidth Hard X-Ray Free-Electron Laser Pulses at SwissFEL

Prat, Eduard; Dijkstal, Philipp; Reiche, S.

doi:10.1103/physrevlett.124.074801

Cited by 19 publications

(7 citation statements)

References 35 publications

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“…Simulations of the SwissFEL pulse at three chirps (1%, 2%, and 4%) are presented in this paper ( Figure 2). For the simulations, the results of measured beam parameters from the machine were used, when it was configured for large bandwidth operation [31]. This characterization of the electron beam was done at the injection point into the undulator, using a transverse deflector in order to obtain time-resolved beam parameters.…”

Section: Swissfel Chirped Broadband Simulationsmentioning

confidence: 99%

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Applications and Limits of Time-to-Energy Mapping of Protein Crystal Diffraction Using Energy-Chirped Polychromatic XFEL Pulses

et al. 2020

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A broadband energy-chirped hard X-ray pulse has been demonstrated at the SwissFEL (free electron laser) with up to 4% bandwidth. We consider the characteristic parameters for analyzing the time dependence of stationary protein diffraction with energy-chirped pulses. Depending on crystal mosaic spread, convergence, and recordable resolution, individual reflections are expected to spend at least ≈ 50 attoseconds and up to ≈ 8 femtoseconds in reflecting condition. Using parameters for a chirped XFEL pulse obtained from simulations of 4% bandwidth conditions, ray-tracing simulations have been carried out to demonstrate the temporal streaking across individual reflections and resolution ranges for protein crystal diffraction. Simulations performed at a higher chirp (10%) emphasize the importance of chirp magnitude that would allow increased observation statistics for the temporal separation of individual reflections for merging and structure determination. Finally, we consider the fundamental limitation for obtaining time-dependent observations using chirped pulse diffraction. We consider the maximum theoretical time resolution achievable to be on the order of 50–200 as from the instantaneous bandwidth of the chirped SASE pulse. We then assess the ability to propagate ultrafast optical pulses for pump-probe cross-correlation under characteristic conditions of material dispersion; in this regard, the limiting factors for time resolution scale with crystal thickness. Crystals that are below a few microns in size will be necessary for subfemtosecond time resolution.

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Section: Swissfel Chirped Broadband Simulationsmentioning

confidence: 99%

“…The new compact XFEL source at the Paul Scherrer Institute, SwissFEL, is able to operate in a broad-bandpass mode: simulated ultrafast hard X-ray SASE pulses have a bandwidth as large as ∆E/E ≈ 4% [30,31]. Such pulses at SwissFEL display an energy chirp, meaning that the central frequency varies with time.…”

Section: Introductionmentioning

confidence: 99%

Applications and Limits of Time-to-Energy Mapping of Protein Crystal Diffraction Using Energy-Chirped Polychromatic XFEL Pulses

et al. 2020

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“…Several ideas have been published for controlling the bandwidth of SASE FELs, for example modified self-seeding to produce narrower line width radiation (Prat and Reiche, 2018), or machine methods to enhance the brightness (Prat and Reiche, 2019). For some experiments, a larger bandwidth is advantageous and this can also be provided (Prat et al, 2020). For crystallography, large bandwidth increases the probability of finding Bragg reflections, and may have applications in spectroscopy.…”

Section: Perspectivesmentioning

confidence: 99%

Atomic, molecular and optical physics applications of longitudinally coherent and narrow bandwidth Free-Electron Lasers

Callegari,

Grum-Grzhimailo,

Ishikawa

et al. 2020

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Short wavelength Free-Electron Lasers (FELs) are the newest light sources available to scientists to probe a wide range of phenomena, with chemical, physical and biological applications, using soft and hard X-rays. These sources include the currently most powerful light sources in the world (hard X-ray sources) and are characterised by extremely high powers and high transverse coherence, but the first FELs had reduced longitudinal coherence. Now it is possible to achieve good longitudinal coherence (narrow bandwidth in the frequency domain) and here we discuss and illustrate a range of experiments utilising this property, and their underlying physics. The primary applications are those which require high resolution (for example resonant experiments), or temporal coherence (for example coherent control experiments). The currently available light sources extend the vast range of laboratory laser techniques to short wavelengths.

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“…The exploration of multiple solutions instead of only one is beneficial for various scientific applications, e.g. for beams with the same temporal profile, but with opposite energy chirp along the electron beam 60 can provide different benefits in FELs [19,20]. In addition, it should be noted that not all potential solutions are equally feasible to implement in practical scientific experiments, e.g.…”

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confidence: 99%

“…3 is crucial for temporal shaping since an under compressed beam and an over compressed beam can provide different benefits in scientific applications. For example, an over 280 compressed scheme has the potential to provide larger bandwidth FEL radiation [19]. Compared to the under compressed beam, however, the over compressed beam also leads to a significant coherent synchrotron radiation (CSR) that can reduce the slice alignment and spoil the 285 transverse emittance of the electron beam [20].…”

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confidence: 99%

Machine Learning-Based Direct Solver for One-To-Many Problems on Temporal Shaping of Electron Beams

Wan¹,

Jiao²,

2021

Preprint

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To control the temporal profile of an electron beam to meet requirements of various advanced scientific applications, a widely-used technique is to manipulate the dispersion terms which turns out to be one-to-many problems. Due to their intrinsic one-to-many property, current popular stochastic optimization approaches on temporal shaping are not very effective, for being trapped into local optima or suggesting only one solution. Here we propose a real-time solver for one-to-many problems of temporal shaping, with the aid of a semi-supervised machine learning method, the conditional generative adversarial network (CGAN). We demonstrate that the CGAN solver can learn the one-to-many dynamics and is able to accurately and quickly predict the required dispersion terms for different custom temporal profiles. This machine learning-based solver overcomes the limitation of the stochastic optimization methods and is expected to have the potential for wide applications to one-to-many problems in other scientific fields.

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Demonstration of Large Bandwidth Hard X-Ray Free-Electron Laser Pulses at SwissFEL

Cited by 19 publications

References 35 publications

Applications and Limits of Time-to-Energy Mapping of Protein Crystal Diffraction Using Energy-Chirped Polychromatic XFEL Pulses

Applications and Limits of Time-to-Energy Mapping of Protein Crystal Diffraction Using Energy-Chirped Polychromatic XFEL Pulses

Atomic, molecular and optical physics applications of longitudinally coherent and narrow bandwidth Free-Electron Lasers

Machine Learning-Based Direct Solver for One-To-Many Problems on Temporal Shaping of Electron Beams

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