Bandwidth broadening of X-ray free electron laser pulses with the natural gradient of planar undulator

Song, Minghao; Yan, Jiawei; Li, Kai; Feng, Chao; Deng, Haixiao

doi:10.1016/j.nima.2017.12.005

Cited by 8 publications

(9 citation statements)

References 49 publications

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“…Two primary methods exist to generate a large-bandwidth free electron laser. One is to use an energy-chirped electron beam [12][13][14]28], and the other is to utilize space-field correlations in the undulator, such as by injecting a head-to-tail tilted beam into a transverse gradient undulator (TGU) [15] or a planar undulator [11]. Using a large energy-chirped electron beam is a simple and natural way to generate broadband XFEL radiation.…”

Section: Broadband Fel Pulse Generation In Sxfelmentioning

confidence: 99%

“…In addition to pursuing narrow-bandwidth FEL pulses, the large-bandwidth operation mode of XFEL has been proposed in recent years [11][12][13][14][15][16]. Because one broadband XFEL pulse covers the entire energy range of absorption spectra and the number of X-ray photons in each pulse reaches 10 12 , in principle, the XAS and XMCD experiments can be accomplished without major interactions with XFEL machine components.…”

Section: Introductionmentioning

confidence: 99%

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Proposal of X-ray absorption spectroscopy and magnetic circular dichroism using broadband free-electron lasers

Deng

Yan

Zhang

et al. 2019

J Synchrotron Radiat

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X‐ray free‐electron lasers (XFELs) have been widely used for applications such as X‐ray crystallography and magnetic spin probes because of their unprecedented performance. Recently, time‐resolved X‐ray magnetic circular dichroism (XMCD) with ultrafast XFEL pulses have made it possible to achieve an instantaneous view of atomic de‐excitation. However, owing to the narrow bandwidth and coherence of XFELs, X‐ray absorption spectroscopy (XAS) and XMCD are time‐ and effort‐consuming for both machine scientists and users of XFELs. In this work, an efficient scheme using a broadband XFEL pulse and single‐shot X‐ray spectrometer is proposed, in which the XAS and XMCD measurements can be accomplished with the same machine conditions. An evolutionary multi‐objective optimization algorithm is used to maximize the XFEL bandwidth offered by the Shanghai Soft X‐ray FEL user facility without additional hardware. A numerical example using MnO is demonstrated, showing that, by using approximately 1000 consecutive XFEL shots with a central photon energy of 650 eV and full bandwidth of 4.4%, precise spectral measurements for XAS and XMCD can be achieved. Additional considerations related to single‐shot XAS and XMCD are discussed.

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Section: Broadband Fel Pulse Generation In Sxfelmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Proposal of X-ray absorption spectroscopy and magnetic circular dichroism using broadband free-electron lasers

Deng

Yan

Zhang

et al. 2019

J Synchrotron Radiat

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“…where � r is the radiation wavelength, � u the undulator period, � the Lorentz factor of electrons and K the undulator parameter, there are basically two paths to generate large-bandwidth radiation with currently available undulators of fixed period. A possible method is to introduce a transverse tilt in the electron bunch passing through downstream undulators with considerable transverse variation of the undulator parameter like transverse gradient undulators (Prat et al, 2016) or natural gradient of planar undulators (Song et al, 2018). This kind of transversely tilted bunches can be achieved by radiofrequency (RF) deflecting cavity or corrugated structure.…”

Section: Introductionmentioning

confidence: 99%

Ultrashort large-bandwidth X-ray free-electron laser generation with a dielectric-lined waveguide

Liu,

Wang,

et al. 2024

J Synchrotron Rad

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Large-bandwidth pulses produced by cutting-edge X-ray free-electron lasers (FELs) are of great importance in research fields like material science and biology. In this paper, a new method to generate high-power ultrashort FEL pulses with tunable spectral bandwidth with spectral coherence using a dielectric-lined waveguide without interfering operation of linacs is proposed. By exploiting the passive and dephasingless wakefield at terahertz frequency excited by the beam, stable energy modulation can be achieved in the electron beam and large-bandwidth high-intensity soft X-ray radiation can be generated. Three-dimensional start-to-end simulations have been carried out and the results show that coherent radiation pulses with duration of a few femtoseconds and bandwidths ranging from 1.01% to 2.16% can be achieved by changing the undulator taper profile.

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“…According to the FEL resonance condition [21], the wavelength of FEL radiation is determined by the electron beam energy and the undulator field parameters. In principle, properly sending the head-tail tilted electron bunches into a transverse gradient undulator [22] or into a planar undulator with natural gradient [23] can make different parts of the bunch experience different magnetic field, and thus generate broadband FEL pulses. Besides that, using electron beams with time-energy correlation is a more natural way to obtain broad-bandwidth FEL, which may be achieved without additional hardware elements in currently existed facilities.…”

Section: Introductionmentioning

confidence: 99%

Generation of large-bandwidth x-ray free electron laser with evolutionary many-objective optimization algorithm

Yan

Deng

2019

Phys. Rev. Accel. Beams

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X-ray free-electron lasers (XFELs) are cutting-edge scientific instruments for a wide range of disciplines. Conventionally, the narrow bandwidth is pursued in an XFEL. However, in recent years, the large-bandwidth XFEL operation schemes are proposed for X-ray spectroscopy and Xray crystallography, in which over-compression is a promising scheme to produce broad-bandwidth XFEL pulses through increasing the electron beam energy chirp. In this paper, combining with the beam yaw correction to overcome the transverse slice misalignment caused by the coherent synchrotron radiation, finding out the over-compression working point of the linac is treated as a many-objective (having four or more objectives) optimization problem, thus the non-dominated sorting genetic algorithm III is applied to the beam dynamic optimization for the first time. Startto-end simulations demonstrate a full bandwidth of 4.6% for Shanghai soft x-ray free-electron laser user facility.

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Bandwidth broadening of X-ray free electron laser pulses with the natural gradient of planar undulator

Cited by 8 publications

References 49 publications

Proposal of X-ray absorption spectroscopy and magnetic circular dichroism using broadband free-electron lasers

Proposal of X-ray absorption spectroscopy and magnetic circular dichroism using broadband free-electron lasers

Ultrashort large-bandwidth X-ray free-electron laser generation with a dielectric-lined waveguide

Generation of large-bandwidth x-ray free electron laser with evolutionary many-objective optimization algorithm

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