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Paper   IPM / P / 8345
School of Physics
  Title:   Self-Fields in Free-Electron Lasers with Planar Wiggler and Ion-Channel Guiding
1.  B. Farrokhi
2.  F. B . Jafary
3.  B. Maraghechi
  Status:   Published
  Journal: J. Phys. D: Appl. Phys.
  Vol.:  39
  Year:  2006
  Pages:   3742-3748
  Supported by:  IPM
A theory of self-electric and self-magnetic fields of a relativistic electron beam passing through a one-dimensional planar wiggler and an ion-channel is presented. The equilibrium orbits and their stability, under the influence of self-electric and self-magnetic fields, are analysed. New unstable orbits, in the first part of the group I orbits, are found. It is shown that for a low energy and high density beam the self-fields can produce very large effects. Stabilities of quasi-steady-state orbits are investigated by analytical and numerical methods and perfect agreement was found. The theory of small signal gain is used to derive a formula for the gain with the self-field effects included. A numerical analysis is conducted to study the self-field effects on the quasi-steady-state orbits and the gain.

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