Non-local theory of a transverse magnetic mode pumped free electron laser

2008 ◽  
Vol 74 (5) ◽  
pp. 585-594
Author(s):  
B. S. SHARMA ◽  
N. K. JAIMAN
Keyword(s):  
Magnetic Field ◽  
Growth Rate ◽  
Free Electron ◽  
Free Electron Laser ◽  
Cyclotron Frequency ◽  
Axial Magnetic Field ◽  
Local Theory ◽  
Instability Growth ◽  
Non Local ◽  
Gamma Factor

AbstractA non-local theory is used to study the effects of the corrugation parameter ε of a plasma-filled slow wave structure, the cyclotron frequency of a pumped magnetic field Ω and the relativistic gamma factor γ0 on the instability growth Γ of a free electron laser in the presence of an external finite axial magnetic field. The dispersion relation is derived and the growth rate is formulated in the Raman regime. The growth rate is approximately proportional to ε. There is a considerable decrease in the instability growth when the cyclotron frequency is close to ω0. The growth rate approximately scales inversely as the 19/2 power of the relativistic gamma factor.

Quantum regime of a plasma-wave-pumped free-electron laser in the presence of an axial magnetic field

2018 ◽  
Vol 25 (2) ◽  
pp. 316-322 ◽  
Author(s):  
H. Shirvani ◽  
S. Jafari
Keyword(s):  
Magnetic Field ◽  
Free Electron ◽  
Free Electron Laser ◽  
Evolution Equations ◽  
Cyclotron Frequency ◽  
Axial Magnetic Field ◽  
Three Dimensional ◽  
Vertical Motion ◽  
Momentum Spread ◽  
Quantum Regime

The quantum regime of a plasma-whistler-wave-pumped free-electron laser (FEL) in the presence of an axial-guide magnetic field is presented. By quantizing both the plasma whistler field and axial magnetic field, anN-particle three-dimensional Hamiltonian of quantum-FEL (QFEL) has been derived. Employing Heisenberg evolution equations and introducing a new collective operator which controls the vertical motion of electrons, a quantum dispersion relation of the plasma whistler wiggler has been obtained analytically. Numerical results indicate that, by increasing the intrinsic quantum momentum spread and/or increasing the axial magnetic field strength, the bunching and the radiation fields grow exponentially. In addition, a spiking behavior of the spectrum was observed with increasing cyclotron frequency which provides an enormous improvement in the coherence of QFEL radiation even in a limit close-to-classical regime, where an overlapping of these spikes is observed. Also, an upper limit of the intrinsic quantum momentum spread which depends on the value of the cyclotron frequency was found.

Dispersion relation and growth rate in a free-electron laser with a background plasma

2015 ◽  
Vol 81 (3) ◽  
Author(s):  
T. Mohsenpour ◽  
B. Maraghechi
Keyword(s):  
Magnetic Field ◽  
Growth Rate ◽  
Dispersion Relation ◽  
Plasma Density ◽  
Free Electron ◽  
Free Electron Laser ◽  
Axial Magnetic Field ◽  
Background Plasma ◽  
Positive Energy ◽  
Induced Velocity

The method of perturbation has been applied to derive a general dispersion relation for a free-electron laser (FEL) with background plasma and helical wiggler in the presence of an axial magnetic field. This dispersion relation is solved numerically to find unstable interactions among all of the wave modes. Numerical calculations show that new coupling between the left wave and positive-energy space-charge of electron beam are found when wiggler induced velocity is large. This coupling does not change with increasing the plasma density. The growth rate of FEL is changed with increasing the plasma density and the normalized axial magnetic field.

Numerical investigations on the effects of geometrical parameters on free electron laser instability

2008 ◽  
Vol 74 (6) ◽  
pp. 741-747
Author(s):  
B. S. SHARMA ◽  
N. K. JAIMAN
Keyword(s):  
Growth Rate ◽  
Electron Beam ◽  
Free Electron ◽  
Free Electron Laser ◽  
Instability Growth Rate ◽  
Magnetized Plasma ◽  
Geometrical Parameters ◽  
Uniform Density ◽  
Backward Wave Oscillator ◽  
Instability Growth

AbstractIn this paper we numerically investigate the effects of various geometrical parameters of a backward wave oscillator (BWO), filled with a magnetized plasma of uniform density and driven by a mild relativistic solid electron beam, on the instability growth rate (Γ) of a free electron laser (FEL). The FEL instability is numerically calculated and the result is compared with the instability growth rate of an annular electron beam for the same set of parameters. The instability growth for a solid electron beam scales inversely to the seventh power of relativistic gamma factor γ0 and directly proportional to the corrugation amplitude.

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