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TUB03 |
Hard X-Ray Self-Seeding at PAL-XFEL | |
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| A hard X-ray self-seeding utilizing time-delayed forward Bragg diffracted photons from thin diamond crystals has been successfully commissioned in a broad spectral range (3.5~14.4 keV), and will be soon provided to user experiments. In the self-seeded mode, the spectral bandwidth is typically 0.2~0.5 eV FWHM in contrast to SASE mode, in which the spectral bandwidth is around 20 eV. This implies that the seeded FEL can be a single longitudinal mode laser since the number of longitudinal mode is 100~200 in the SASE operation. In this case, the photon number of filtered FEL is expected to be fluctuated 100% from the narrow bandwidth filtering out of random and spiky SASE spectra. We found that our energy stability of electron bunches (10-4) do not degrade much the seeding performance and the large variation of the seeded FEL intensity will be from the seeding probability. The advantages of 30 um thin diamond crystal and diagnostic tool for the self-seeding will be also presented. | ||
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Slides TUB03 [28.431 MB] | |
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| TUD04 | Cavity-Based Free-Electron Laser Research and Development: A Joint Argonne National Laboratory and SLAC National Laboratory Collaboration | 282 |
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| One solution for producing longitudinally coherent FEL pulses is to store and recirculate the output of an amplifier in an X-ray cavity so that the X-ray pulse can interact with following fresh electron bunches over many passes. The X-ray FEL oscillator (XFELO) and the X-ray regenerative amplifier FEL (XRAFEL) concepts use this technique and rely on the same fundamental ingredients to realize their full capability. Both schemes require a high repetition rate electron beam, an undulator to provide FEL gain, and an X-ray cavity to recirculate and monochromatize the radiation. The shared infrastructure, complementary performance characteristics, and potentially transformative FEL properties of the XFELO and XRAFEL have brought together a joint Argonne National Laboratory (ANL) and SLAC National Laboratory (SLAC) collaboration aimed at enabling these schemes at LCLS-II. We present plans to install a rectangular X-ray cavity in the LCLS-II undulator hall and perform experiments employing 2-bunch copper RF linac accelerated electron beams. This includes performing cavity ring-down measurements and 2-pass gain measurements for both the low-gain XFELO and the high-gain RAFEL schemes. | ||
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Slides TUD04 [12.425 MB] | |
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-TUD04 | |
| About • | paper received ※ 25 August 2019 paper accepted ※ 29 August 2019 issue date ※ 05 November 2019 | |
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| THP051 | Generating Trains of Attosecond Pulses with a Free-Electron Laser | 692 |
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| Recently, a Hard X-ray Self-Seeding setup was commissioned at PAL XFEL. Its main purpose is to increase the temporal coherence of FEL radiation in an active way. We report another application of this setup to generate trains of short sub-femtosecond pulses with linked phases. We discuss preliminary results of both experiment and corresponding simulations as well as indirect diagnostics of the radiation properties. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-THP051 | |
| About • | paper received ※ 20 August 2019 paper accepted ※ 27 August 2019 issue date ※ 05 November 2019 | |
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