Degradation in gain for a free electron laser amplifier due to electron momentum spread

  • A. Fruchtman
  • J. L. Hirshfield
Article

Abstract

A finite spread in axial momentum for the electron beam in a free electron laser amplifier is shown to decrease the small-signal gain. For millimeter and sub-millimeter wave amplifiers, where exponential growth dominates the gain, it is shown that the gain is approximately 3 db below that for a cold beam if the relative momentum spread (Δu/u)1/2 = (Go/248)1/2o/L), where Go≫1 is the gain in db for the cold-beam case, λo is the magnetic wiggler period, and L is the amplifier length. Exact numerical examples are given for representative FEL amplifiers at 35 and 550 GHz.

Key words

free electron laser amplifier electron momentum spread 

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References

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Copyright information

© Plenum Publishing Corporation 1981

Authors and Affiliations

  • A. Fruchtman
    • 1
  • J. L. Hirshfield
    • 1
    • 2
  1. 1.Center for Plasma Physics and Racah Institute of PhysicsHebrew University of JerusalemIsrael
  2. 2.Mason LaboratoryYale UniversityNew Haven

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