Experimental validation of collective effects modeling at injector section of X-ray free-electron laser

Zagorodnov, Igor; Tomin, Sergey; Chen, Ye; Brinker, Frank

doi:10.1016/j.nima.2021.165111

Cited by 5 publications

(6 citation statements)

References 15 publications

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“…The codes OCELOT [13] and GENESIS [14] are used. The EuXFEL photoinjector [15] is optimized in the simulations taking into account the collective effects as studied in detail in [16]. The close-to cathode beam dynamics is carefully considered using the 3D approach as reported in [17].…”

Section: Simulationmentioning

confidence: 99%

Virtual commissioning of the European XFEL for advanced user experiments at photon energies beyond 25 keV using low-emittance electron beams

Chen

Brinker

Decking

et al. 2023

J. Phys.: Conf. Ser.

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Growing interests in ultra-hard X-rays are pushing forward the frontier of commissioning the European X-ray Free-Electron Laser (XFEL) for routine operation towards the sub-ångström regime, where a photon energy of 25 keV (0.5 Å) and above is desired. Such X-rays allow for larger penetration depths and enable the investigation of materials in highly absorbing environments. Delivering the requested X-rays to user experiments is of crucial importance for the XFEL development. Unique capabilities of the European XFEL are formed by combining a high energy linac and the long variable-gap undulator systems for generating intense X-rays at 25 keV and pushing the limit even further to 30 keV. However, the FEL performance relies on achievable electron bunch qualities. Low-emittance electron bunch production, and the associated start-to-end modelling of beam physics thus becomes a prerequisite to dig into the XFEL potentials. Here, we present the obtained simulation results from a virtual commissioning of the XFEL for the user experiments at 25 keV and beyond, including the optimized electron bunch qualities and corresponding FEL lasing performance. Experimental results at 30 keV from the first test run are presented.

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Section: Simulationmentioning

confidence: 99%

Virtual commissioning of the European XFEL for advanced user experiments at photon energies beyond 25 keV using low-emittance electron beams

Chen

Brinker

Decking

et al. 2023

J. Phys.: Conf. Ser.

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“…The electron beam dynamics at the European XFEL accelerator has been recently discussed in [7] and [8]. In the last work, an experimental validation of the collective effects modeling at the European XFEL injector was presented.…”

Section: Modelling Of the Experiments With Collective Effects And The...mentioning

confidence: 99%

“…In the last work, an experimental validation of the collective effects modeling at the European XFEL injector was presented. Here we use the same approach from [8] to simulate the beam dynamics, namely (1) the dynamics of the electron beam in the gun was simulated using ASTRA code [10],…”

Section: Modelling Of the Experiments With Collective Effects And The...mentioning

confidence: 99%

Accurate measurement of uncorrelated energy spread in electron beam

Tomin

Zagorodnov

Decking

et al. 2021

Phys. Rev. Accel. Beams

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We present measurements of slice energy spread at the injector section of the European X-Ray Free Electron Laser for an electron bunch with charge of 250 pC. Two methods considered in the paper are based on measurements at the dispersive section after a transverse deflecting structure (TDS). The first approach uses measurements at different beam energies. We show that with a proper scaling of the TDS voltage with the beam energy the rms error of the measurement is less than 0.3 keV for the energy spread of 6 keV. In the second approach we demonstrate that keeping the beam energy constant but adjusting only the optics we are able to simplify the measurement complexity and to reduce the rms error below 0.1 keV. The accuracy of the measurement is confirmed by numerical modelling including beam transport effects and collective beam dynamics of the electron beam. The slice energy spread measured at the European XFEL for the beam charge of 250 pC is nearly 3 times lower as the one reported recently at SwissFEL for the same cathode material and the beam charge of 200 pC.

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“…Despite widely available high performance computing, numerically calculating relativistic charged particle dynamics is still a challenge and an open area of research for large collections of particles undergoing collective effects in dynamics involving plasma turbulence 22 , space charge (SC) forces 23,24 , and coherent synchrotron radiation (CSR) 25,26 . For example, the photo-injectors of modern X-ray free electron lasers such as the LCLS, SwissFEL, and EuXFEL and plasma wakefield accelerators such as FACET-II can produce high quality intense bunches with few picosecond rms lengths of up to 2 nC charge per bunch that are accelerated and squeezed down to lengths of tens to hundreds of femtoseconds [27][28][29][30][31][32] .…”

Section: Introductionmentioning

confidence: 99%

Physics-constrained machine learning for electrodynamics without gauge ambiguity based on Fourier transformed Maxwell's equations

Leon,

Scheinker

2024

Preprint

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We utilize a Fourier transformation-based representation of Maxwell's equations to develop physics-constrained neural networks (PCNN) for electrodynamics without gauge ambiguity, which we label the Fourier-Helmholtz-Maxwell Neural Operator (FoHM-NO) method. In this approach, both of Gauss's laws and Faraday's law are built in as hard constraints, as well as the longitudinal component of Ampère-Maxwell in Fourier space, assuming the continuity equation. An encoder-decoder network acts as a solution operator for the transverse components of the Fourier transformed vector potential, A⟂,z(k,t), whose two degrees of freedom are used to predict the electromagnetic fields. This method was tested on two electron beam simulations. Among the models investigated, it was found that a U-Net architecture exhibited the best performance as it trained quicker, was more accurate and generalized better than the other architectures examined. We demonstrate that our approach is useful for solving Maxwell's equations for the electromagnetic fields generated by intense relativistic charged particle beams and that it generalizes well to unseen test data, while being orders of magnitude quicker than conventional simulations. We show that the model can be re-trained to make highly accurate predictions in as few as 20 epochs on a previously unseen data set.

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Experimental validation of collective effects modeling at injector section of X-ray free-electron laser

Cited by 5 publications

References 15 publications

Virtual commissioning of the European XFEL for advanced user experiments at photon energies beyond 25 keV using low-emittance electron beams

Virtual commissioning of the European XFEL for advanced user experiments at photon energies beyond 25 keV using low-emittance electron beams

Accurate measurement of uncorrelated energy spread in electron beam

Physics-constrained machine learning for electrodynamics without gauge ambiguity based on Fourier transformed Maxwell's equations

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