Absolute and convective instabilities in two-dimensional free-electron lasers
Abstract
Computer simulations of the free-electron laser have been carried out using a two-and-one-half dimensional fully electromagnetic relativistic particle code. It has been found that waves propagating obliquely with respect to the electron beam are always unstable with appreciable growth rates and, therefore, mode competition is an important consideration in the design of free-electron lasers. Furthermore, electromagnetic waves with group velocities opposite to the direction of electron beam propagation can be absolutely unstable. It is shown that the absolutely unstable waves can completely disrupt the electron beam and any laser oscillaton; therefore, they are extremely detrimental to the operation of free electron lasers. However, it has been found that one can stabilize the absolute instability by taking particular precautions in the design of free-electron lasers.
- Publication:
-
Physics of Fluids
- Pub Date:
- May 1981
- DOI:
- 10.1063/1.863460
- Bibcode:
- 1981PhFl...24..899K
- Keywords:
-
- Computerized Simulation;
- Free Electron Lasers;
- Laser Stability;
- Relativistic Electron Beams;
- Wave Dispersion;
- Electromagnetic Fields;
- Electromagnetic Wave Transmission;
- Fourier Transformation;
- Group Velocity;
- Systems Simulation;
- Lasers and Masers