&lt;title&gt;Exotic harmonic generation schemes in high-gain free-electron lasers&lt;/title&gt;

Biedron, Sandra; Bartolini, R.; Ciocci, F.; Dattoli, G.; Fawley, William M.; Felici, G.; Freund, H.P.; Nuhn, Heinz-Dieter; Ottaviani, P. L.; Renieri, A.

doi:10.1117/12.469761

Cited by 8 publications

(4 citation statements)

References 29 publications

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“…The density modulation, which evolves in the undulator as a consequence of the interaction of the beam with the combined fields of the undulator and the co-propagating electromagnetic wave, develops substantial Fourier components at higher harmonics of the fundamental when the FEL approaches saturation, and emission at the corresponding wavelengths occurs. There is widespread interest in this process, because emission of high-order harmonics represents a significant resource to extend the operating wavelength range of FELs 33 – 36 , and also because the simultaneous generation of radiation pulses with multiple frequencies can be implemented in multi-color experiments where the different light beams interact with the sample under study 37 .…”

Section: Generation Of Phase-coherent Xuv Light From a Seeded Felmentioning

confidence: 99%

Coherent control schemes for the photoionization of neon and helium in the Extreme Ultraviolet spectral region

Giannessi

Allaria

Callegari

et al. 2018

Sci Rep

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The seeded Free-Electron Laser (FEL) FERMI is the first source of short-wavelength light possessing the full coherence of optical lasers, together with the extreme power available from FELs. FERMI provides longitudinally coherent radiation in the Extreme Ultraviolet and soft x-ray spectral regions, and therefore opens up wide new fields of investigation in physics. We first propose experiments exploiting this property to provide coherent control of the photoionization of neon and helium, carry out numerical calculations to find optimum experimental parameters, and then describe how these experiments may be realized. The approach uses bichromatic illumination of a target and measurement of the products of the interaction, analogous to previous Brumer-Shapiro-type experiments in the optical spectral range. We describe operational schemes for the FERMI FEL, and simulate the conditions necessary to produce light at the fundamental and second or third harmonic frequencies, and to control the phase with respect to the fundamental. We conclude that a quantitative description of the phenomena is extremely challenging for present state-of-the-art theoretical and computational methods, and further development is necessary. Furthermore, the intensity available may already be excessive for the experiments proposed on helium. Perspectives for further development are discussed.

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Section: Generation Of Phase-coherent Xuv Light From a Seeded Felmentioning

confidence: 99%

Coherent control schemes for the photoionization of neon and helium in the Extreme Ultraviolet spectral region

Giannessi

Allaria

Callegari

et al. 2018

Sci Rep

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“…This is presented in Fig. 6, where the cases m=n ¼ 1. phenomenon of the nonlinear harmonic generation that results from the strong electron beam microbunching present at the fundamental wavelength [23,41]. In this case, the harmonics experience a growth similar to that of the fundamental with gain lengths scaling as the inverse of the harmonic number ð1=mÞ.…”

Section: Analytical and Numerical Datamentioning

confidence: 99%

“…Experiments on dual frequency production have been recently carried out on them with different methods [11][12][13][14][15][16][17][18] in various regimes of radiation frequency. Some of the initially proposed designs [19][20][21] were based on the use of staggered undulator magnets with different values of deflecting parameters to achieve lasing at two distinct wavelengths [22][23][24][25][26][27], an idea recently revisited and demonstrated in the x rays' range at the FEL Linac Coherent Light Source (LCLS) [8,11]. Another option, recently demonstrated at the FERMI soft x-ray seeded FEL [10], involves the use of either a chirped or a two-color seed laser [13,14].…”

Section: Introductionmentioning

confidence: 99%

Two-color free-electron laser with two orthogonal undulators

Dattoli

Mirian

Palma

et al. 2014

Phys. Rev. ST Accel. Beams

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We discuss a two-color self-amplified spontaneous emission free-electron laser (FEL) amplifier where the emission is obtained from two orthogonally polarized undulators with different periods and field intensities. Nonaveraged and averaged equations are compared. The two radiations have not only different frequencies, but also different polarizations, while the total length of the device does not change with respect to usual single-color FELs. The wavelengths of two different colors can be changed by choosing different periods, while variation in the magnetic strengths can be used to modify the gain lengths.

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“…This microbunching, in turn, gives rise to enhanced nonlinear harmonic growth and can become the dominant harmonic growth mechanism [2][3][4][5][6][7]. The alternative method of the two-beam FEL was proposed to generate more intensified short wavelength power based on harmonic generation mechanism [8,9].…”

Section: Introductionmentioning

confidence: 99%

Simulation of the effect of wiggler imperfections on harmonic generation in two-beam free-electron lasers

Zahedian

Maraghechi

2012

Phys. Rev. ST Accel. Beams

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A three-dimensional simulation of a free-electron laser (FEL) with two beams is used to study the sensitivity of the third harmonic due to wiggler imperfections. In the two-beam FEL, for a fundamental wavelength of 107.5 nm, the power will be converted to the third harmonic at a shorter wavelength, in this case in the extreme ultraviolet at 35.8 nm. In this arrangement, the fundamental resonance of the higher energy beam coincides with the third harmonic of the lower energy beam, for this energy conversion to take place. For enhanced focusing, a planar wiggler with parabolic pole face is considered. Investigation of the effect of wiggler errors on the efficiencies of harmonic and fundamental resonance of the two-beam and the one-beam FEL shows that the average efficiency for the third harmonic in the two-beam FEL is decreased by 36% while the reduction of average efficiency for the fundamental of the two-beam is 55% and for the third harmonic of the one-beam is 48%. This shows that the third harmonic radiation in the two-beam FEL is less sensitive to wiggler imperfection compared to its fundamental as well as the third harmonic in the one-beam FEL. The reason is that the energy that transfers to the third harmonic of the two-beam FEL comes from both electron beams. It was also found that, for almost all cases, standard deviation increases with an increasing level of wiggler imperfection while, for the two-beam FEL, saturation length of the fundamental resonance decreases and the third harmonic increases with increasing wiggler imperfection.

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<title>Exotic harmonic generation schemes in high-gain free-electron lasers</title>

Cited by 8 publications

References 29 publications

Coherent control schemes for the photoionization of neon and helium in the Extreme Ultraviolet spectral region

Coherent control schemes for the photoionization of neon and helium in the Extreme Ultraviolet spectral region

Two-color free-electron laser with two orthogonal undulators

Simulation of the effect of wiggler imperfections on harmonic generation in two-beam free-electron lasers

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