Intrabeam Scattering in an X-ray FEL Driver

Huang, Z.

doi:10.2172/839686

Cited by 13 publications

(12 citation statements)

References 1 publication

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“…Simulation results produced with ASTRA [29,30] predict an uncorrelated energy spread before compression well below 1 keV. These simulations include space-charge but do not consider intrabeam scattering [31,32] or cathode effects. The large measured energy spreads could be attributed to intrabeam scattering or to the fact that SwissFEL uses cesium telluride cathodes (which have a longer emission time than the standard copper material used in most other FEL facilities).…”

Section: Comparison With Simulations and Other Experimental Observationsmentioning

confidence: 99%

High-resolution dispersion-based measurement of the electron beam energy spread

Prat

Dijkstal

Malyzhenkov

et al. 2020

Phys. Rev. Accel. Beams

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The energy spread of the electron beam is a critical parameter in x-ray free-electron lasers (XFELs) and needs to be optimized for best performance. The uncorrelated energy spread of the electrons can be a few keV or less in XFEL injectors, thus very challenging to measure. The standard method to characterize the electron beam energy spread, consisting in streaking the beam with a transverse deflector and measuring the time-resolved beam size of the electrons in a dispersive location for a single electron beam energy, has a typical resolution of several keV. To overcome this limitation we introduce a novel method to measure the beam size at a dispersive location for different beam energies so that it is possible to disentangle the beam size contributions related to the energy spread, the intrinsic beam size and the monitor resolution. As a consequence, the energy spread can be characterized with a much higher precision and resolution than in the standard approach. We also suggest to perform measurements for different deflection amplitudes so that the energy spread induced by the transverse deflector can be subtracted properly. The scheme does not require any additional hardware and thus can be readily applied in any standard XFEL facility. Numerical simulations and experimental results at SwissFEL confirm the validity of our method. Our calculations show that the approach can be used to significantly overcome the resolution of the standard approach and measure energy spreads well below 1 keV. As an example we present energy spreads of few keV measured at the SwissFEL injector.

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Section: Comparison With Simulations and Other Experimental Observationsmentioning

confidence: 99%

High-resolution dispersion-based measurement of the electron beam energy spread

Prat

Dijkstal

Malyzhenkov

et al. 2020

Phys. Rev. Accel. Beams

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“…The IBS [53][54][55] also has significant effects on the bunching factor of EEHG [50]. The IBS effect can be hardly handled in the simulations above.…”

Section: Performance With Three-dimensional Effectsmentioning

confidence: 99%

“…For a single-stage EEHG, the coherent signal at 225th harmonic will be totally overwhelmed by the noise induced by CSR and ISR effects, as shown in Figure 8c, where one can observe that the final spectrum becomes a typical SASE structure. The IBS [53][54][55] also has significant effects on the bunching factor of EEHG [50]. The IBS effect can be hardly handled in the simulations above.…”

Section: I Amentioning

confidence: 99%

Extending the Photon Energy Coverage of a Seeded Free-Electron Laser via Reverse Taper Enhanced Harmonic Cascade

et al. 2021

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External seeded free-electron lasers (FELs) hold promising prospects for producing intense coherent radiation at high harmonics of a conventional laser. The practical harmonic up-conversion efficiencies of current seeding techniques are limited by various three-dimensional effects on the electron beam. In this paper, a novel method is proposed to extend the wavelength coverage of a seeded FEL by combining the reverse taper undulator with the echo-enabled harmonic generation. The proposed technique can significantly enhance the bunching at ultra-high harmonics and preserve the electron beam qualities from degradation by deleterious effects. Theoretical analysis and numerical simulation are performed, and the results demonstrate that stable, intense, nearly fully coherent FEL pulses with photon energy up to 1 keV can be generated. The proposed technique may open up new opportunities to obtain laser-like pulses at sub-nanometer wavelength.

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“…Studies indicate that the CSR from the final two dipoles in the first chicane has the greatest impact on the spectrum. beam density and with transport length [47][48][49][50], favoring a compact EEHG layout, in conflict with ISR requirements for large, weak magnets. IBS increases the energy spread and reduces the bunching.…”

Section: B Eehg Challengesmentioning

confidence: 99%

Soft x-ray seeding studies for the SLAC Linac Coherent Light Source II

Hemsing

Marcus

Fawley

et al. 2019

Phys. Rev. Accel. Beams

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We present the results from studies of soft x-ray seeding options for the LCLS-II x-ray free electron laser (FEL) at SLAC. The LCLS-II will use superconducting accelerator technology to produce x-ray pulses at up to 1 MHz repetition rate using 4 GeV electron beams. If properly seeded, these pulses will be nearly fully coherent, and highly stable in photon energy, bandwidth, and intensity, thus enabling unique experiments with intense high-resolution soft x-rays. Given the expected electron beam parameters from start to end simulations and predicted FEL performance, our studies reveal echo enabled harmonic generation (EEHG) and soft x-ray self-seeding (SXRSS) as promising and complementary seeding methods. We find that SXRSS has the advantage of simplicity and will deliver 5-35 times higher spectral brightness than EEHG in the 1-2 nm range, but lacks some of the potential for phase-stable multipulse and multicolor FEL operations enabled by external laser seeding with EEHG.

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Intrabeam Scattering in an X-ray FEL Driver

Cited by 13 publications

References 1 publication

High-resolution dispersion-based measurement of the electron beam energy spread

High-resolution dispersion-based measurement of the electron beam energy spread

Extending the Photon Energy Coverage of a Seeded Free-Electron Laser via Reverse Taper Enhanced Harmonic Cascade

Soft x-ray seeding studies for the SLAC Linac Coherent Light Source II

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