Two-stream instability in free electron lasers with a planar wiggler and an axial guide magnetic field

2008 ◽  
Vol 15 (4) ◽  
pp. 043103 ◽  
Author(s):  
H. Mehdian ◽  
S. Saviz ◽  
A. Hasanbeigi
Keyword(s):  
Magnetic Field ◽  
Free Electron ◽  
Free Electron Lasers ◽  
Guide Magnetic Field ◽  
Stream Instability

THE THEORY OF FREE ELECTRON LASERS WITH AXIAL GUIDE MAGNETIC FIELD

1993 ◽  
Vol 04 (04) ◽  
pp. 315-348 ◽  
Author(s):  
N. S. GINZBURG ◽  
YU. V. NOVOZHILOVA ◽  
N. YU. PESKOV
Keyword(s):  
Magnetic Field ◽  
Electromagnetic Wave ◽  
Free Electron ◽  
High Efficiency ◽  
Doppler Frequency ◽  
Free Electron Lasers ◽  
Efficiency Enhancement ◽  
Negative Mass ◽  
Transverse Inhomogeneity ◽  
Guide Magnetic Field

Amplification and generation schemes of free electron lasers with a helical undulator and homogeneous guiding magnetic field are considered. A description of the process of pumping bounce oscillations of electrons in the adiabatically tapered undulator field is presented. The electron beam interacts with the electromagnetic wave in the region of constant amplitude of the undulator field where electrons move along stationary helical trajectories. Linear and nonlinear theory of such interaction is developed when electrons are under the undulator and combined synchronism with the electromagnetic wave. In the latter case the radiation is accompanied by excitation of electron oscillations near the equilibrium trajectory. A range of parameters for undulator synchronism is found where a considerable Doppler frequency up-conversion can be realized simultaneously with high efficiency (for amplifiers more then 30%). The mechanism of efficiency enhancement in this region is described. The influence of HF space charge (including negative mass effects) and the transverse inhomogeneity of the undulator field is discussed.

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