An extended model of the quantum free-electron laser

M. S. Brown, J. R. Henderson, L. T. Campbell, B. W. J. McNeil

Research output: Contribution to journalArticle

2 Citations (Scopus)

Abstract

Previous models of the quantum regime of operation of the Free Electron Laser
(QFEL) have performed an averaging and the application of periodic boundary conditions to the coupled Maxwell – Schrödinger equations over short, resonant wavelength intervals of the interaction. Here, an extended, one-dimensional model of the QFEL interaction is presented in the absence of any such averaging or application of periodic boundary conditions, the absence of the latter allowing electron diffusion processes to be modeled throughout the pulse. The model is used to investigate how both the steady-state (CW) and pulsed regimes of QFEL operation are affected. In the steady-state regime it is found that the electrons are confined to evolve as a 2-level system, similar to the previous QFEL models. In the pulsed regime Coherent Spontaneous Emission (CSE) due to the shape of the electron pulse current distribution is shown to be present in the QFEL regime for the first time. However, unlike the classical case, CSE in the QFEL is damped by the effects of quantum diffusion of the electron wavefunction. Electron recoil from the QFEL interaction can also cause a diffusive drift between the recoiled and non-recoiled parts of the electron pulse wavefunction, effectively removing the recoiled part from the primary
electron-radiation interaction.
LanguageEnglish
Pages33429-33438
Number of pages10
JournalOptics Express
Volume25
Issue number26
DOIs
Publication statusPublished - 25 Dec 2017

Fingerprint

free electron lasers
electrons
spontaneous emission
pulses
interactions
boundary conditions
electron diffusion
current distribution
Maxwell equation
intervals
causes
radiation
wavelengths

Keywords

  • free-electron lasers (FELs)
  • coherent optical effects
  • electron wavefunction
  • electron-radiation interaction

Cite this

Brown, M. S. ; Henderson, J. R. ; Campbell, L. T. ; McNeil, B. W. J. / An extended model of the quantum free-electron laser. In: Optics Express. 2017 ; Vol. 25, No. 26. pp. 33429-33438.
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abstract = "Previous models of the quantum regime of operation of the Free Electron Laser(QFEL) have performed an averaging and the application of periodic boundary conditions to the coupled Maxwell – Schr{\"o}dinger equations over short, resonant wavelength intervals of the interaction. Here, an extended, one-dimensional model of the QFEL interaction is presented in the absence of any such averaging or application of periodic boundary conditions, the absence of the latter allowing electron diffusion processes to be modeled throughout the pulse. The model is used to investigate how both the steady-state (CW) and pulsed regimes of QFEL operation are affected. In the steady-state regime it is found that the electrons are confined to evolve as a 2-level system, similar to the previous QFEL models. In the pulsed regime Coherent Spontaneous Emission (CSE) due to the shape of the electron pulse current distribution is shown to be present in the QFEL regime for the first time. However, unlike the classical case, CSE in the QFEL is damped by the effects of quantum diffusion of the electron wavefunction. Electron recoil from the QFEL interaction can also cause a diffusive drift between the recoiled and non-recoiled parts of the electron pulse wavefunction, effectively removing the recoiled part from the primaryelectron-radiation interaction.",
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An extended model of the quantum free-electron laser. / Brown, M. S.; Henderson, J. R.; Campbell, L. T.; McNeil, B. W. J.

In: Optics Express, Vol. 25, No. 26, 25.12.2017, p. 33429-33438.

Research output: Contribution to journalArticle

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AB - Previous models of the quantum regime of operation of the Free Electron Laser(QFEL) have performed an averaging and the application of periodic boundary conditions to the coupled Maxwell – Schrödinger equations over short, resonant wavelength intervals of the interaction. Here, an extended, one-dimensional model of the QFEL interaction is presented in the absence of any such averaging or application of periodic boundary conditions, the absence of the latter allowing electron diffusion processes to be modeled throughout the pulse. The model is used to investigate how both the steady-state (CW) and pulsed regimes of QFEL operation are affected. In the steady-state regime it is found that the electrons are confined to evolve as a 2-level system, similar to the previous QFEL models. In the pulsed regime Coherent Spontaneous Emission (CSE) due to the shape of the electron pulse current distribution is shown to be present in the QFEL regime for the first time. However, unlike the classical case, CSE in the QFEL is damped by the effects of quantum diffusion of the electron wavefunction. Electron recoil from the QFEL interaction can also cause a diffusive drift between the recoiled and non-recoiled parts of the electron pulse wavefunction, effectively removing the recoiled part from the primaryelectron-radiation interaction.

KW - free-electron lasers (FELs)

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