Thermal loading on self-seeding monochromators in x-ray free electron lasers

Qu, Zhengxian; Ma, Yanbao; Zhou, Guan-Qun; Wu, Juhao

doi:10.1016/j.nima.2020.163936

Cited by 10 publications

(6 citation statements)

References 23 publications

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“…The generated X-ray pulse (yellow) is characterized by the X-ray Gas Monitor (XGM) pulse energy monitor and the HIgh REsolution hard X-ray (HIREX) single-shot spectrometer (grey), located in the photon beam transport approximatively 500 m downstream of the undulator. repetition rates increases the average brightness of X-ray pulses of up to two orders of magnitude, but at photon energies lower than about 8 keV it also generates significant heat-load on the HXRSS crystal, leading to intra-train spectral shifts and broadening [31,32,33]. In this paper we report the first experimental results on how a cascaded HXRSS can be used to compensate these detrimental effects.…”

Section: Cascaded Hxrss Systemmentioning

confidence: 95%

“…However, similar to passive monochromatization, at the high repetition rate available at the European XFEL, operation at photon energies lower than about 8 keV generates excessive heat-load on the HXRSS crystal, resulting in intratrain spectral shifts and broadening [31,32,33]. To cope with these detrimental effects, a cascaded two-chicane HXRSS system has been designed and installed at the European XFEL.…”

Section: Introductionmentioning

confidence: 99%

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Cascaded hard X-ray self-seeded free-electron laser at MHz-repetition-rate

Liu

Grech

Guetg

et al. 2023

Preprint

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The European XFEL is currently the only high-repetition rate hard X-ray free electron laser (FEL) facility in operation worldwide. We significantly improved its capabilities by installing a cascaded Hard X-ray Self-Seeding (HXRSS) system, composed of two single-crystal monochromators. With this system, mJ-level pulses in the photon energy range of 6 -14keV with a bandwidth around 1eV (corresponding to about 1mJ/eV spectral density) were generated. Combined with the burst-mode, multi-MHz repetition rate of the European XFEL accelerator, the cascaded HXRSS setup provides two orders of magnitude higher average spectral brightness than any other FEL facility. At 2.25 MHz repetition rate and photon energies in the 6-7 keV range, we observed for the first time heat-load effects on the HXRSS crystals, substantially altering the spectra of subsequent X-ray pulses. Using the cascaded self-seeding scheme, we successfully reduced this effect to below detection level. These results open up exciting possibilities in a wide range of scientific fields, exploiting the extreme brightness and the narrow bandwidth of HXRSS pulses.

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Section: Cascaded Hxrss Systemmentioning

confidence: 95%

Section: Introductionmentioning

confidence: 99%

Cascaded hard X-ray self-seeded free-electron laser at MHz-repetition-rate

Liu

Grech

Guetg

et al. 2023

Preprint

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“…The absorptance then was imported as an input into the thermal and mechanical module, where the quasi-static strain and displacement field was simulated and exported back to the diffraction module to assess the seed quality of the next XFEL pulse. More details of the simulation module can be found in our previous work (Qu et al, 2020a;Qu, 2020) To evaluate the thermal load effects on the hard X-ray selfseeding, we choose a typical set of parameters: the SASE central photon energy is selected as 8.3 keV with 3 mJ pulse energy, 1.2 Â 10 À3 relative bandwidth, 40 mm (FWHM) spot size and 4.54 MHz repetition rate (Liu et al, 2019). The diamond crystal monochromator is in (4 0 0) reflection of (1 0 0)-plane surface crystal with geometry specified by Dong et al (2017).…”

Section: Simulation Methodsmentioning

confidence: 99%

Dynamic pulse-to-pulse thermal load effects in pulse-train-mode self-seeded X-ray free-electron laser

Zhou

et al. 2020

J Synchrotron Radiat

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Thermal load has been a haunting factor that undermines the brightness and coherence of the self-seeded X-ray free-electron laser. Different from uniformly pulsed mode, in pulse train mode a thermal quasi-steady state of the crystal monochromator may not be reached. This leads to a dynamic thermal distortion of the spectral transmission curves and seed quality degradation. In this paper, the pulse-to-pulse thermal load effects on the spectral transmission curves and seed quality are shown, and some instructive information for the tuning process is provided.

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“…Based on Bushuev’s work, Qu et al [ 18 ] further formulated the factors (such as the maximum strain and non-uniform thermal load) that affect the central wavelength shift and the distortion of the rocking curve, and they discussed these effects separately and quantitatively by an analytical method. They applied their method to estimate the thermal load on the self-seeding monochromator [ 19 , 20 ] . The above theoretical methods have successfully illustrated the central wavelength shift and the distortion of rocking curves.…”

Section: Introductionmentioning

confidence: 99%

X-ray diffraction performance of thermally distorted crystals

Yang

Liu

Hu³

et al. 2023

High Pow Laser Sci Eng

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The development of high-brightness X-ray free electron lasers (XFELs), such as hard X-ray self-seeding free electron lasers and XFEL oscillators (XFELOs), brings a severe challenge to the crystal monochromator due to a strong non-uniform thermal load. The distortion caused by spatial temperature gradients can severely affect the optical performance of crystals. Therefore, this paper presents a model to estimate the performance of non-uniform thermally distorted crystals. The model not only takes into account thermal strain, slope error and incident angle deviation, but also considers temperature-dependent factors such as the Debye–Waller factor and electric susceptibility. Our investigation indicates that the Debye–Waller factor reduces the height and bandwidth of rocking curves, and the impact of the electric susceptibility is tiny. The proposed model can describe the distortion of the reflectivity and transmissivity curves of non-uniform thermally loaded crystals and can be applied in the design of crystal monochromators, crystal splitters, crystal compressors and XFELOs.

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Thermal loading on self-seeding monochromators in x-ray free electron lasers

Cited by 10 publications

References 23 publications

Cascaded hard X-ray self-seeded free-electron laser at MHz-repetition-rate

Cascaded hard X-ray self-seeded free-electron laser at MHz-repetition-rate

Dynamic pulse-to-pulse thermal load effects in pulse-train-mode self-seeded X-ray free-electron laser

X-ray diffraction performance of thermally distorted crystals

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