ELECTRON DYNAMICS AND HARMONIC GENERATION IN THE FREE-ELECTRON LASER.

Persistent Link:
http://hdl.handle.net/10150/186014
Title:
ELECTRON DYNAMICS AND HARMONIC GENERATION IN THE FREE-ELECTRON LASER.
Author:
AL-ABAWI, HAZIM YOUNIS.
Issue Date:
1982
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Abstract:
The free-electron laser (FEL) is a device for converting kinetic energy in a relativistic electron beam directly into laser light. A classical theory of the FEL is discussed. This theory uses the Boltzmann distribution to describe the electrons and Maxwell equation to describe the evolution of the laser field. The harmonic expansion of the Boltzmann equation leads to a set of "quasi-Bloch" equations describing the electron distribution. The behavior of the momentum distribution is discussed theoretically in the small-signal regime of the FEL. The distribution function changes in nontrivial ways. The electron distribution does not only experience a recoil, but is also subject to spread through the amplification process. The recoil plays a relatively minor role compared to the spread. This behavior of the electron distribution may play an important role in the efficiency of the FEL. Free-electron lasers, except for those using helical wigglers, are predicted in most cases to generate higher harmonics, of the fundamental optical frequency, in the forward direction. The basic equations describing this process are derived by using the multiple-scaling perturbation theory, which leads to the slowly-varying Maxwell and Boltzmann equations. Harmonic generation in the FEL offers a possible means to extend the wavelength range of the device towards high frequency. Numerical calculations are shown for CW operation using a linearly polarized wiggler. Higher harmonic emission becomes enhanced as the magnetic field is increased and as the energy spread in the electron beam is reduced. Coherent pulse propagation in the picosecond pulse regime of the FEL is treated. Coherent transient effects such as laser lethargy are discussed. The effect of laser lethargy is seen to play an important role in the pulsed FEL, as it does in conventional swept-gain amplifiers based on an atomic medium. Numerical calculations of the harmonics in the pulsed FEL are presented. The optical pulses show a ringing behavior which is sensitive to the reflectivity of the cavity mirrors and to the electron current.
Type:
text; Dissertation-Reproduction (electronic)
Keywords:
Free electron lasers.
Degree Name:
Ph.D.
Degree Level:
doctoral
Degree Program:
Optical Sciences; Graduate College
Degree Grantor:
University of Arizona

Full metadata record

DC FieldValue Language
dc.language.isoenen_US
dc.titleELECTRON DYNAMICS AND HARMONIC GENERATION IN THE FREE-ELECTRON LASER.en_US
dc.creatorAL-ABAWI, HAZIM YOUNIS.en_US
dc.contributor.authorAL-ABAWI, HAZIM YOUNIS.en_US
dc.date.issued1982en_US
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.description.abstractThe free-electron laser (FEL) is a device for converting kinetic energy in a relativistic electron beam directly into laser light. A classical theory of the FEL is discussed. This theory uses the Boltzmann distribution to describe the electrons and Maxwell equation to describe the evolution of the laser field. The harmonic expansion of the Boltzmann equation leads to a set of "quasi-Bloch" equations describing the electron distribution. The behavior of the momentum distribution is discussed theoretically in the small-signal regime of the FEL. The distribution function changes in nontrivial ways. The electron distribution does not only experience a recoil, but is also subject to spread through the amplification process. The recoil plays a relatively minor role compared to the spread. This behavior of the electron distribution may play an important role in the efficiency of the FEL. Free-electron lasers, except for those using helical wigglers, are predicted in most cases to generate higher harmonics, of the fundamental optical frequency, in the forward direction. The basic equations describing this process are derived by using the multiple-scaling perturbation theory, which leads to the slowly-varying Maxwell and Boltzmann equations. Harmonic generation in the FEL offers a possible means to extend the wavelength range of the device towards high frequency. Numerical calculations are shown for CW operation using a linearly polarized wiggler. Higher harmonic emission becomes enhanced as the magnetic field is increased and as the energy spread in the electron beam is reduced. Coherent pulse propagation in the picosecond pulse regime of the FEL is treated. Coherent transient effects such as laser lethargy are discussed. The effect of laser lethargy is seen to play an important role in the pulsed FEL, as it does in conventional swept-gain amplifiers based on an atomic medium. Numerical calculations of the harmonics in the pulsed FEL are presented. The optical pulses show a ringing behavior which is sensitive to the reflectivity of the cavity mirrors and to the electron current.en_US
dc.typetexten_US
dc.typeDissertation-Reproduction (electronic)en_US
dc.subjectFree electron lasers.en_US
thesis.degree.namePh.D.en_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplineOptical Sciencesen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.identifier.proquest8217389en_US
dc.identifier.oclc681925625en_US
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