Self-Amplification of Coherent Energy Modulation in Seeded Free-Electron Lasers

X-ray free-electron lasers (XFELs) generate X-ray by electrons flying through a periodic magnetic field.-XFELs are the leading X-ray sources with ultra-high brightness and ultra-short duration.-XFELs can be launched from either the shot noise of the electron beam or the seed.-XFEL-laser collision is proposed to learn the nature of vacuum at SHINE.-XFELs are being combined with intense lasers and synchrotron radiation light sources.

show abstract

“…Using this scheme, an HGHG FEL that uses an energy modulation as small as 1.8 times the slice energy spread has been demonstrated. 146 …”

Section: Current Developments and Future Prospects For Xfelsmentioning

confidence: 99%

Features and futures of X-ray free-electron lasers

et al. 2021

Self Cite

View full text Add to dashboard Cite

show abstract

“…Limited by existing hardware, it is difficult to increase the peak power of the seed laser or change the dipole magnet. The energy modulation amplitude of a factor of 1.4 greater than the slice energy spread is too weak to lase at the sixth harmonic directly; consequently, the selfmodulation method 31 was employed to further enhance the energy modulation. In the experiment, the pulse energy of the seed laser was kept at 38.10 μJ.…”

Section: Lasing Feasibility Of a Seeded Felmentioning

confidence: 99%

First observation of laser-beam interaction in a dipole magnet

et al. 2021

Self Cite

View full text Add to dashboard Cite

As a new-generation light source, free-electron lasers (FELs) provide high-brightness x-ray pulses at the angstrom-femtosecond space and time scales. The fundamental physics behind the FEL is the interaction between an electromagnetic wave and a relativistic electron beam in an undulator, which consists of hundreds or thousands of dipole magnets with an alternating magnetic field. We report the first observation of the laser-beam interaction in a pure dipole magnet in which the electron beam energy modulation with a 40-keV amplitude and a 266-nm period is measured. We demonstrate that such an energy modulation can be used to launch a seeded FEL, that is, lasing at the sixth harmonic of the seed laser in a high-gain harmonic generation scheme. The results reveal the most basic process of the FEL lasing and open up a new direction for the study and exploitation of laser-beam interactions.

show abstract

“…It has been used as a method to speed up the FEL process in SASE operation, when the total amplifier length is not sufficient for a given wavelength [59][60][61]. In addition, it is used in a seeding scheme when the seed laser peak power is not sufficient to increase the energy modulation required in seeding [17]. The simplest configuration of an optical klystron consists of two undulators tuned at the same resonant wavelength and a dispersive section in between them.…”

Section: Optical Klystronmentioning

confidence: 99%

“…This leads to high peak brightness FEL pulses, but limited average flux, in contrast to the number of electron bunches available. In order to address this limitation, alternatives have been recently studied to increase the repetition rate of seeding schemes by reducing the seed laser power requirements [17,18], and in this paper, we propose an oscillator-amplifier setup.…”

Section: Introductionmentioning

confidence: 99%

Advanced Scheme to Generate MHz, Fully Coherent FEL Pulses at nm Wavelength

et al. 2021

View full text Add to dashboard Cite

Current FEL development efforts aim at improving the control of coherence at high repetition rate while keeping the wavelength tunability. Seeding schemes, like HGHG and EEHG, allow for the generation of fully coherent FEL pulses, but the powerful external seed laser required limits the repetition rate that can be achieved. In turn, this impacts the average brightness and the amount of statistics that experiments can do. In order to solve this issue, here we take a unique approach and discuss the use of one or more optical cavities to seed the electron bunches accelerated in a superconducting linac to modulate their energy. Like standard seeding schemes, the cavity is followed by a dispersive section, which manipulates the longitudinal phase space of the electron bunches, inducing longitudinal density modulations with high harmonic content that undergo the FEL process in an amplifier placed downstream. We will discuss technical requirements for implementing these setups and their operation range based on numerical simulations.

show abstract

Self-Amplification of Coherent Energy Modulation in Seeded Free-Electron Lasers

Cited by 35 publications

References 40 publications

Features and futures of X-ray free-electron lasers

Features and futures of X-ray free-electron lasers

First observation of laser-beam interaction in a dipole magnet

Advanced Scheme to Generate MHz, Fully Coherent FEL Pulses at nm Wavelength

Contact Info

Product

Resources

About