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Compton and Raman free electron laser stability properties for a warm electron beam propagating through a helical magnetic wiggler

Published online by Cambridge University Press:  13 March 2009

John A. Davies ,
Ronald C. Davidson  and
George L. Johnston
John A. Davies
Affiliation:
Clark University, Worcester, MA 01610
Ronald C. Davidson
Affiliation:
Plasma Fusion Center, Massachusetts Institute of Technology, Cambridge, MA 02139
George L. Johnston
Affiliation:
Plasma Fusion Center, Massachusetts Institute of Technology, Cambridge, MA 02139
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Abstract

This paper gives an extensive analytical and numerical characterization of the growth-rate curves (imaginary frequency versus wavenumber) derived from the free electron laser dispersion relation for a warm relativistic electron beam propagating through a constant-amplitude helical magnetic wiggler field. The electron beam is treated as infinite in transverse extent. A detailed mathematical analysis is given of the exact dispersion relation and its Compton approximation for the case of a water-bag equilibrium distribution function (uniform distribution in axial momentum pz). Applicability of the water-bag results to the case of a Gaussian equilibrium distribution in pz is tested numerically. One result of the water-bag analysis is a set of validity conditions for the Compton approximation. Numerical and analytical results indicate that these conditions are applicable to the Gaussian case far outside the parameter range where the individual water-bag and corresponding Gaussian growth rate curves agree.

Type
Research Article
Information
Journal of Plasma Physics , Volume 37 , Issue 2 , April 1987 , pp. 255 - 298
Copyright
Copyright © Cambridge University Press 1987

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References

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