Onset of steady oscillations in free electron lasers
Abstract
An analytical model is presented to demonstrate that the initiation of steady oscillations in a free electron laser (FEL) occurs in two stages. It is shown that the amplitude of the fundamental mode and the relations between modes is established, and a slow damping of the secondary modes ensues. A linear stage is characterized by nointeracting modes which grow independently, although one mode does grow fastest and is designated the fundamental mode. When the linear stage ends the fundamental mode is dominant, and consideration is given to the nonlinear effects caused by the amplitude of this mode. Damping of secondary modes is determined to occur exponentially, although in a three-mode FEL a quasiequilibrium is established with secondary modes arrayed symmetrically about the fundamental. Extension of the model to the cases of more than three modes is indicated.
- Publication:
-
Soviet Physics Technical Physics
- Pub Date:
- November 1981
- Bibcode:
- 1981SPTP...26.1452C