Nonlinear analysis of Ubitron/Free-Electron Laser amplifiers in three dimensions. Memorandum report

Technical Report · Tue Oct 08 00:00:00 EDT 1985

OSTI ID:6204308

Ganguly, A K; Freund, H P

The nonlinear evolution of the Free-Electron Laser/Ubitron amplifier is investigated numerically for a configuration consisting of helical wiggler and axial-guide magnetic fields. A set-coupled nonlinear differential equation is derived in three dimensions which governs the self-consistent evolution of either the TE or TM modes in a loss-free cylindrical waveguide and the trajectories of an ensemble of electrons. The initial conditions are chosen to model the adiabatic injection of a cold, cylindrically symmetric electron beam into an interaction region in which the wiggler amplitude rises slowly from zero to a constant level in ten wiggler periods. Both self-field and space-charge effect were neglected in the formulation, and the analysis is valid for the High-Gain Compton regime of operation. Numerical simulations are conducted to model an amplifier operating in the neighborhood of 35 GHz, and for electron-beam energies of energies of 250 keV and 1 MeV. The growth rate in the linear regime prior to saturation is found to be in substantial agreement with the predictions based on a linear theory of the instability, and the saturation efficiency is consistent with that expected on the basis of simple, heuristic phase trapping arguments. Substantial enhancements in the efficiency are found to occur due to the presence of the axial/guide field.

• Research Organization: Naval Research Lab., Washington, DC (USA)
• OSTI ID: 6204308
• Report Number(s): AD-A-160631/8/XAB; NRL-MR-5669
• Country of Publication: United States
• Language: English

Related Subjects

42 ENGINEERING
AMPLIFIERS
FREE ELECTRON LASERS
EFFICIENCY
ELECTRON BEAMS
INJECTION
LOSSES
NUMERICAL ANALYSIS
SATURATION
SPACE CHARGE
TRAJECTORIES
WAVEGUIDES
WIGGLER MAGNETS
BEAMS
ELECTRICAL EQUIPMENT
ELECTROMAGNETS
ELECTRONIC EQUIPMENT
EQUIPMENT
INTAKE
LASERS
LEPTON BEAMS
MAGNETS
MATHEMATICS
PARTICLE BEAMS
420300* - Engineering- Lasers- (-1989)
420800 - Engineering- Electronic Circuits & Devices- (-1989)