Enhanced Harmonic Generation in Terahertz FELs: Influence of Pre-Bunching and Undulator Geometry on Spectral and Angular Emission

Fuente: arXiv
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Auteurs principaux: Choobini, A. A. Molavi, Ghaffari-Oskooei, S. S., Farahi, F., Aghamir, F. M.
Format: Preprint
Publié: 2024
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author Choobini, A. A. Molavi
Ghaffari-Oskooei, S. S.
Farahi, F.
Aghamir, F. M.
author_facet Choobini, A. A. Molavi
Ghaffari-Oskooei, S. S.
Farahi, F.
Aghamir, F. M.
contents Both theoretical and numerical analyses are conducted to investigate terahertz (THz) radiation emission from free-electron lasers. The angular and spectral characteristics of radiation are analytically evaluated leveraging Linenard Wiechert field formalism, The analysis spanned across varying beam profiles and undulator parameters, including harmonic order, magnetic strength, period, and electron energy. Fourier analysis of the electric field reveals strong sensitivity of spectral content to underlying beam dynamics and undulator structure. Planar undulators tend to generate radiation with more prominent side lobes, especially at higher harmonics, while helical undulators produce narrower, more focused emission profiles. Importantly, the polarization and forward directed nature of the radiation are governed primarily by the resonant conditions and beam dynamics, rather than the undulator geometry itself. Building on these analytical insights, GENESIS simulations are employed to quantify the evolution of the bunching factor and radiation intensity under varying energy spread and plasma dispersion. The results show that increased undulator periods enhance radiation coherence, while transitions to wiggler regimes (at high magnetic parameters) lead to angular broadening and lateral lobe formation. Among all beam profiles studied Gaussian, Lorentzian, biGaussian, and prebunched the prebunched configuration demonstrates superior harmonic generation capabilities, albeit with high sensitivity to energy spread and plasma effects.
format Preprint
id arxiv_https___arxiv_org_abs_2404_16503
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Enhanced Harmonic Generation in Terahertz FELs: Influence of Pre-Bunching and Undulator Geometry on Spectral and Angular Emission
Choobini, A. A. Molavi
Ghaffari-Oskooei, S. S.
Farahi, F.
Aghamir, F. M.
Accelerator Physics
Plasma Physics
Both theoretical and numerical analyses are conducted to investigate terahertz (THz) radiation emission from free-electron lasers. The angular and spectral characteristics of radiation are analytically evaluated leveraging Linenard Wiechert field formalism, The analysis spanned across varying beam profiles and undulator parameters, including harmonic order, magnetic strength, period, and electron energy. Fourier analysis of the electric field reveals strong sensitivity of spectral content to underlying beam dynamics and undulator structure. Planar undulators tend to generate radiation with more prominent side lobes, especially at higher harmonics, while helical undulators produce narrower, more focused emission profiles. Importantly, the polarization and forward directed nature of the radiation are governed primarily by the resonant conditions and beam dynamics, rather than the undulator geometry itself. Building on these analytical insights, GENESIS simulations are employed to quantify the evolution of the bunching factor and radiation intensity under varying energy spread and plasma dispersion. The results show that increased undulator periods enhance radiation coherence, while transitions to wiggler regimes (at high magnetic parameters) lead to angular broadening and lateral lobe formation. Among all beam profiles studied Gaussian, Lorentzian, biGaussian, and prebunched the prebunched configuration demonstrates superior harmonic generation capabilities, albeit with high sensitivity to energy spread and plasma effects.
title Enhanced Harmonic Generation in Terahertz FELs: Influence of Pre-Bunching and Undulator Geometry on Spectral and Angular Emission
topic Accelerator Physics
Plasma Physics
url https://arxiv.org/abs/2404.16503