Multi-order harmonic lasing with a modified wiggler

Asakawa, M.; Nakao, Naoya; Ohkubo, H.; Ishida, Takayuki; Watanabe, Takeshi; Yasuda, Eiji; Okuda, Y.; Fujita, Masayuki; Chen, J.; Moon, Ahsa; Roy, P.K.; Kuruma, S.; Imasaki, K.; Mima, Kunioki; Ohigashi, Nobuhisa; Tsunawaki, Yoshiaki; Nakai, S.; Yamanaka, Chiyoe

doi:10.1016/0168-9002(95)01383-0

Cited by 14 publications

(6 citation statements)

References 8 publications

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“…It is done by the shimming by ferromagnetic materials and it can enhance the radiation of high harmonics. [66][67][68][69][70][71][72] The measurements of the strength of the field harmonics in these special undulators showed ≈20-30% of the main field amplitude. [70,73,74] In the common planar undulators, used in X-ray FELs, which we will study in what follows, the amplitude of the field harmonic dH 0 is small, d ≲ 0.05.…”

Section: Spontaneous Radiation From Undulatorsmentioning

confidence: 99%

“…[70,73,74] In the common planar undulators, used in X-ray FELs, which we will study in what follows, the amplitude of the field harmonic dH 0 is small, d ≲ 0.05. However, special bi-harmonic undulators exist, where the amplitude of the field harmonic can reach 10-30% of the main field, d ≈ 0.1-0.3; [66][67][68][69][70][71][72][73][74] usually a radiation field of the undulator can be theoretically reproduced by taking into account the first and third field harmonics. [30,31] The effect of the field harmonics on the UR was thoroughly studied in many works, for example, lately it was addressed in refs.…”

Section: Spontaneous Radiation From Undulatorsmentioning

confidence: 99%

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Theoretical Analysis of the Radiation Properties of Some Major X‐Ray Free Electron Lasers

Zhukovsky

2021

Annalen der Physik

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A theoretical analysis of the radiation in X-ray free electron lasers (FELs) LCLS, PAL-XFEL, SwissFEL, as well as SACLA, FLASH 2, and European XFEL is presented. Major losses in FELs are analytically accounted for and analyzed, using exact expressions for the Bessel factors in terms of the generalized Bessel functions. This allows distinguishing the contributions of key parameters and accounting for the losses individually for each harmonic, considering higher sensitivity of the electron-photon interaction at higher harmonic wavelengths. The harmonic power evolution along FELs and the spectral width of the radiation lines is studied. The theoretical results are analyzed and are compared with the available experimental data for the FEL experiments. The harmonic generation and amplification in the FELs are modeled and studied with the harmonic lasing self-seed (HLSS) with separate buncher and radiator, and the results are compared with those for SASE. The spectral properties of the radiation are analytically calculated and compared with the measured spectral characteristics. The advantages of HLSS versus SASE FEL are elucidated in the examples of FLASH2, European XFEL, and SwissFEL. The prospected radiation properties of LCLS-II FEL are analyzed and the possibilities of using harmonics in this FEL are proposed.

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Section: Spontaneous Radiation From Undulatorsmentioning

confidence: 99%

Section: Spontaneous Radiation From Undulatorsmentioning

confidence: 99%

Theoretical Analysis of the Radiation Properties of Some Major X‐Ray Free Electron Lasers

Zhukovsky

2021

Annalen der Physik

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“…By increasing the harmonic field component aptly, the harmonic radiation can be enhanced [6]. Therefore some methods for this purpose were proposed, such as putting high permeability shims inside the undulator [7], optimizing the magnetic blocks size in a permanent magnet undulator [8]. Ratios of the third harmonics magnetic field to the fundamental magnetic field approaching 30% have been measured experimentally by Halbach [9].…”

Section: Introductionmentioning

confidence: 99%

Effect of undulator harmonics field on free-electron laser harmonic generation

Jia

2011

Phys. Rev. ST Accel. Beams

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The harmonics field effect of a planar undulator on free-electron laser (FEL) harmonic generation has been analyzed. For both the linear case and the nonlinear case, the harmonic fraction of the radiation can be characterized by the coupling coefficients. The modification of the coupling coefficients is given when the third harmonics magnetic field component exists, thus the enhancement of the harmonic radiation can be predicted. The numerical results show that with the third harmonics magnetic field component that has the opposite sign to the fundamental, the intensity of third-harmonic radiation can be increased distinctly for both the small signal gain and the nonlinear harmonic generation. The increase is larger for the smaller undulator deflecting parameter.

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“…Therefore, in the case of a modified wiggler field, the operation at the third harmonic wavelength λ 3 = 0.04 cm is achieved by using electron beam with 13% less energy compared to the conventional wiggler tuned to the same wavelength λ = 0.04 cm. In Asakawa et al (1996) and Nakao et al (1998), the linear FEL gain of modified wiggler with the harmonic wiggler field component smaller than the fundamental and the decrease in the fundamental wiggler field in order to shorten the wavelength is reported, but small relative gain is shown. In the present study, we are going to have optimum increase of the third harmonic gain relative to conventional wiggler with less energy compared with the conventional wiggler at the same wavelength.…”

Section: Numerical Resultsmentioning

confidence: 99%

“…In the modified wiggler, appropriate controlling of the amplitude and phase of harmonic wiggler field increase the bunching of harmonic and improves its radiation. Due to the simplicity of this harmonic wiggler which consists of conventional planar wiggler and high permeability shims, various kinds of modified wiggler field can be developed easily and economically (Asakawa et al 1995;1996). Suitable wiggler schemes known as nonconventional wigglers, to provide both the saturated power at fundamental and its harmonics, have been suggested for various purposes within the framework of FEL studies.…”

Section: Introductionmentioning

confidence: 99%

Nonlinear third harmonic radiation in thermal free electron laser with modified wiggler

Bazouband

Maraghechi

2015

J. Plasma Phys.

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Simulation of free electron laser (FEL) with modified wiggler consisting of a conventional planar wiggler with third harmonic field component is presented. A set of self consistent nonlinear differential equations is derived and solved numerically by Runge–Kutta method. The optimum amplitudes of fundamental and third harmonic wiggler filed are obtained to increase the third harmonic radiation in comparison with conventional wiggler and also to have lower electron beam energy compared to conventional wiggler with the same wavelength. For the thermal effect the axial energy spread of electron beam, without any spread in the transverse velocity, is assumed. A peculiar region is found in which there is a sharp increase of the radiation amplitude. Thermal effect of the electron beam was found to be irregular in this peculiar region.

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Multi-order harmonic lasing with a modified wiggler

Cited by 14 publications

References 8 publications

Theoretical Analysis of the Radiation Properties of Some Major X‐Ray Free Electron Lasers

Theoretical Analysis of the Radiation Properties of Some Major X‐Ray Free Electron Lasers

Effect of undulator harmonics field on free-electron laser harmonic generation

Nonlinear third harmonic radiation in thermal free electron laser with modified wiggler

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