Relativistic Raman backscattering in an electron beam with ion-channel guiding and its application in free-electron laser

2005 ◽  
Vol 12 (11) ◽  
pp. 113106 ◽  
Author(s):  
A. A. Kordbacheh ◽  
B. Maraghechi ◽  
B. Farokhi ◽  
J. E. Willett
Keyword(s):  
Electron Beam ◽  
Ion Channel ◽  
Free Electron ◽  
Free Electron Laser

Comparative study of electron motion and stability for different focusing regimes in a free-electron laser with three-dimensional helical wiggler

2015 ◽  
Vol 81 (5) ◽  
Author(s):  
Jing-Yue Xu ◽  
S.-J. Wang ◽  
Y.-G. Xu ◽  
Y.-P. Ji ◽  
X.-X. Liu ◽  
...  
Keyword(s):  
Electron Beam ◽  
Ion Channel ◽  
Free Electron ◽  
Free Electron Laser ◽  
Three Dimensional ◽  
Larmor Radius ◽  
Electron Motion ◽  
Magnetic Focusing ◽  
Laser Wave ◽  
The Stability

Since the electromagnetic energy gained by the laser wave in a free-electron laser (FEL) is transferred from the kinetic energy loss of a relativistic electron beam, the stability of electron motion is one of the key factors that affect FEL performance. In this paper the stability of electron motion is compared for different focusing regimes. It is demonstrated that the natural focusing regime of a three-dimensional wiggler is easily broken by the self-field of the electron beam. The magnetic focusing regime of an axial guide magnetic field is based on the superposition of a strong Larmor rotation on the transverse quiver motion of the electrons, while the electric focusing regime of an ion-channel guiding field generates an electric force to counteract the divergent effect of the beam self-field. In comparison with the magnetic focusing regime of an external magnetic system, the electric focusing regime of an ion-channel guiding field may yield smaller instantaneous Larmor radius and slighter Larmor-centre deviation from the axis and provide better motion stability.

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

1985 ◽  
Vol 33 (3) ◽  
pp. 387-423 ◽  
Author(s):  
John A. Davies ◽  
Ronald C. Davidson ◽  
George L. Johnston
Keyword(s):  
Magnetic Field ◽  
Electron Beam ◽  
Dispersion Relation ◽  
Free Electron ◽  
Free Electron Laser ◽  
Relativistic Electron Beam ◽  
Cold Electron ◽  
Wiggler Magnetic Field ◽  
Laser Stability

This paper gives an extensive characterization of the range of validity of the Compton and Raman approximations to the exact free electron laser dispersion relation for a cold, relativistic electron beam propagating through a constantamplitude helical wiggler magnetic field. The electron beam is treated as infinite in transverse extent. Specific properties of the exact and approximate dispersion relations are investigated analytically and numerically. In particular, a detailed numerical analysis is carried out to determine the range of validity of the Compton approximation.

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