Inclusion of space-charge effects with Maxwell's equations in the single-particle analysis of free-electron lasers
Abstract
A self-consistent analysis is presented of the behavior of the electromagnetic field and the modulated electron beam in the single-particle representation in a free-electron laser taking into account space-charge effects in the strong-interaction regime. A set of coupled equations describing the interrelations between the electron beam and the radiation field in the small-signal limit is derived from the Lorentz force equations for the electron-radiation interaction and the Maxwell equations of field generation by the modulated electron beam, and the equations are solved by decoupling the equations into a sixth-order differential equation for the modulation functions. It is found that the electron beam modulation is described by a three-wave solution. The variation of the radiation field has a more complicated structure, with field variations of the interference-like and exponential-like types depending on frequency mismatch, plasma frequency and pumping strength. Plasma resonance is observed at high electron densities in an oscillator due to single-pass gain maximization. The analysis is then applied to a specific example resembling a traveling wave tube.
- Publication:
-
IEEE Journal of Quantum Electronics
- Pub Date:
- August 1981
- DOI:
- 10.1109/JQE.1981.1071304
- Bibcode:
- 1981IJQE...17.1387S
- Keywords:
-
- Electron Beams;
- Free Electron Lasers;
- Maxwell Equation;
- Plasma-Electromagnetic Interaction;
- Space Charge;
- Electron Energy;
- Electron Pumping;
- Lorentz Force;
- Magnetohydrodynamic Stability;
- Plasma Waves;
- Poisson Equation;
- Self Consistent Fields;
- Traveling Wave Tubes;
- Lasers and Masers