PAL-XFEL laser heater commissioning

Lee, JaeHyun; Han, Jang-Hui; Lee, Sojeong; Hong, Juho; Kim, Chul Hoon; Min, Chang Ki; Ko, In Soo

doi:10.1016/j.nima.2016.11.001

Cited by 27 publications

(12 citation statements)

References 10 publications

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“…First, an electron beam with an energy of 10 GeV, a 200 pC bunch charge, an average current of 2.0 kA, 66 fs in length with a normalized emittance of 0.5 mm-mrad, and an un-correlated energy spread of 0.01% is generated using ELEGANT code [37] by taking into account the space-charge effects and the microbunching instabilities [38]. The popular ELEGANT code has been used to track the particle dynamics in six dimensional phase space coordinates.…”

Section: Terawatt-attosecond Hard X-ray Pulse Generationmentioning

confidence: 99%

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Terawatt-Isolated Attosecond X-ray Pulse Using a Tapered X-ray Free Electron Laser

2017

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High power attosecond (as) X-ray pulses are in great demand for ultrafast dynamics and high resolution microscopy. We numerically demonstrate the generation of a~230 attosecond, 1.5 terawatt (TW) pulse at a photon energy of 1 keV, and a 115 attosecond, 1.2 TW pulse at a photon energy of 12.4 keV, using the realistic electron beam parameters such as those of Korean X-ray free electron laser (XFEL) in a tapered undulator configuration. To compensate the energy loss of the electron beam and maximize its radiation power, a tapering is introduced in the downstream section of the undulator. It is found that the tapering helps in not only amplifying a target radiation pulse but also suppressing the growth of satellite radiation pulses. Tapering allows one to achieve a terawatt-attosecond pulse only with a 60 m long undulator. Such an attosecond X-ray pulse is inherently synchronized to a driving optical laser pulse; hence, it is well suited for the pump-probe experiments for studying the electron dynamics in atoms, molecules, and solids on the attosecond time-scale. For the realization of these experiments, a high level of synchronization up to attosecond precision between optical laser and X-ray pulse is demanded, which can be possible by using an interferometric feedback loop.

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Section: Terawatt-attosecond Hard X-ray Pulse Generationmentioning

confidence: 99%

“…Sci. 2017, 7, 614 4 of 11 effects and the microbunching instabilities [38]. The popular ELEGANT code has been used to track the particle dynamics in six dimensional phase space coordinates.…”

Section: Terawatt-attosecond Hard X-ray Pulse Generationmentioning

confidence: 99%

Terawatt-Isolated Attosecond X-ray Pulse Using a Tapered X-ray Free Electron Laser

2017

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“…This instability amplifies the e-beam energy and density modulation and increases its energy spread up to a level that can be detrimental not only to the FEL gain process [9,20], but also to the beam brightness in storage rings and linacs [21,22]. MBI can be suppressed by a laser heater (LH) [8], which was first installed at the Linac Coherent Light Source (LCLS) and has been widely used in other FEL facilities [9,15,20,23]. The heater consists essentially of a short undulator within a chicane and a copropagating infrared (IR) laser that modulates and increases the energy spread of the e beam by about one order of magnitude and without exceeding FEL tolerances.…”

mentioning

confidence: 99%

Laguerre-Gaussian Mode Laser Heater for Microbunching Instability Suppression in Free-Electron Lasers

et al. 2020

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Microbunching instability (MBI) driven by beam collective effects is known to be detrimental to highbrightness storage rings, linacs, and free-electron lasers (FELs). One known way to suppress this instability is to induce a small amount of energy spread to an electron beam by a laser heater. The distribution of the induced energy spread greatly affects MBI suppression and can be controlled by shaping the transverse profile of the heater laser. Here, we present the first experimental demonstration of effective MBI suppression using a LG 01 transverse laser mode and compare the improved results with respect to traditional Gaussian transverse laser mode at the Linac Coherent Light Source. The effects on MBI suppression are characterized by multiple downstream measurements, including longitudinal phase space analysis and coherent radiation spectroscopy. We also discuss the role of LG 01 shaping in soft x-ray selfseeded FEL emission, one of the most advanced operation modes of a FEL for which controlled suppression of MBI is critical.

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“…Laser heaters have proven to be invaluable components of short wavelength FELs 4,24,34,39 , which are capable of mitigating this instability. The laser heater (LH) in its nominal configuration consists of a small dispersive chicane, in the centre of which is an undulator.…”

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confidence: 99%

Characterisation of microbunching instability with 2D Fourier analysis

Brynes

Akkermans

Allaria

et al. 2020

Sci Rep

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The optimal performance of high-brightness free-electron lasers (FELs) is limited by the microbunching instability, which can cause variations in both the slice energy spread and longitudinal profile of electron beams. In this paper, we perform 2D Fourier analysis of the full bunch longitudinal phase space, such that modulations in both planes can be studied simultaneously. Unlike the standard 1D analysis, this method is able to reveal modulations in a folded phase space, which would otherwise remain uncovered. Additionally, the plasma oscillation between energy and density modulations is also revealed by this method. The damping of the microbunching instability, through the use of a laser heater, is also analysed with this technique. We confirm a mitigation of the amplitude of modulation and a red-shift of the microbunching frequency as the energy spread added increases. As an outcome of this work, a systematic experimental comparison of the development of the instability in the presence of different compression schemes is here presented for the first time.

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PAL-XFEL laser heater commissioning

Cited by 27 publications

References 10 publications

Terawatt-Isolated Attosecond X-ray Pulse Using a Tapered X-ray Free Electron Laser

Terawatt-Isolated Attosecond X-ray Pulse Using a Tapered X-ray Free Electron Laser

Laguerre-Gaussian Mode Laser Heater for Microbunching Instability Suppression in Free-Electron Lasers

Characterisation of microbunching instability with 2D Fourier analysis

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