Hostname: page-component-77c89778f8-gvh9x Total loading time: 0 Render date: 2024-07-17T09:44:03.608Z Has data issue: false hasContentIssue false
  • English
  • Français

Pulse shapes for absolute and convective free-electron-laser instabilities

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, Massachusetts 01610, U.S.A.
Ronald C. Davidson
Affiliation:
Plasma Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, U.S.A.
George L. Johnston
Affiliation:
Plasma Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, U.S.A.
Get access Rights & Permissions [Opens in a new window]

Abstract

This paper contains an analysis of pulse shapes produced by a delta-function disturbance of the equilibrium state of a relativistic electron beam propagating through a constant-amplitude, helical magnetic wiggler field. Pulse shapes are determined by using the relativistic pinch-point techniques developed by Bers, Ram and Francis. Two pulses are produced corresponding to a convective upshifted pulse (representing the production of the high-frequency radiation desired in a free electron laser) and a downshifted pulse. The downshifted instability may be convective or absolute, depending upon the beam density and momentum spread. Parameter regimes in which the downshifted instability is convective are investigated. It is found that momentum spreads sufficiently large to suppress the absolute instability reduce the growth rate of the upshifted pulse to negligible values. Pulse shapes computed by using the Raman and Compton approximations are compared with exact pulse shapes. It is found that the Raman approximation should be applied to the downshifted regime for most systems of practical interest.

Type
Research Article
Information
Journal of Plasma Physics , Volume 40 , Issue 1 , August 1988 , pp. 1 - 37
Copyright
Copyright © Cambridge University Press 1988

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

REFERENCES

Bernstein, I. B. & Hirshfield, J. L. 1979 Phys. Rev. A 20, 1661.CrossRefGoogle Scholar
Bers, A. 1983 Handbook of Plasma Physics, vol. 1. Basic Plasma Physics 1 (ed. Galeev, A. A. & Sudan, R. N.), chap. 3.2. North-Holland.Google Scholar
Bers, A., Ram, A. K. & Francis, G. 1984 Phys. Rev. Lett. 53, 1457.CrossRefGoogle Scholar
Briggs, R. J. 1964 Electron-Stream Interactions with Plasmas. MIT Press.CrossRefGoogle Scholar
Cary, J. R. & Kwan, T. J. T. 1981 Phys. Fluids, 24, 729.CrossRefGoogle Scholar
Davidson, R. C. & Uhm, H. S. 1980 Phys. Fluids, 23, 2076.CrossRefGoogle Scholar
Davies, J. A., Davidson, R. C. & Johnston, G. L. 1985 J. Plasma Phys. 33, 387.CrossRefGoogle Scholar
Davies, J. A., Davidson, R. C. & Johnston, G. L. 1987 J. Plasma Phys. 37, 255.CrossRefGoogle Scholar
de Groot, S. R., van Leeuwen, W. A. & van Weert, Ch. G. 1980 Relativistic Kinetic Theory. North-Holland.Google Scholar
Dimos, A. M. & Davidson, R. C. 1985 Phys. Fluids, 28, 677.CrossRefGoogle Scholar
Elias, G. R., Fairbank, W. M., Madey, J. M., Schwettman, H. A. & Smith, T. I. 1976 Phys. Lett. 36, 717.CrossRefGoogle Scholar
Fajans, J. & Bekefi, G. 1986 Phys. Fluids, 29, 3461.CrossRefGoogle Scholar
Jackson, J. D. 1975 Classical Electrodynamics. Wiley.Google Scholar
Kroll, N. M. & McMullin, W. A. 1978 Phys. Rev. A 17, 300.CrossRefGoogle Scholar
Kwan, T. J. T. & Cary, J. R. 1981 Phys. Fluids, 24, 899.CrossRefGoogle Scholar
Kwan, T., Dawson, J. M. & Lin, A. T. 1977 Phys. Fluids, 20, 581.CrossRefGoogle Scholar
Liewer, P. C., Lin, A. T. & Dawson, J. M. 1981 a Phys. Rev. A 23, 1251.CrossRefGoogle Scholar
Liewer, P. C., Lin, A. T., Dawson, J. M. & Zales-Caponi, M. 1981 b Phys. Fluids, 24, 1364.CrossRefGoogle Scholar
Sprangle, P. & Smith, R. A. 1980 Phys. Rev. A 21, 293.CrossRefGoogle Scholar
Steinberg, B., Gover, A. & Ruschin, S. 1986 Phys. Rev. A 33, 421.CrossRefGoogle Scholar