| Paper | Title | Page |
|---|---|---|
| TUPPH026 | Dispersion Effects in Short Pulse Waveguide FEL | 378 |
|
||
|
The influence of waveguide dispersion on the FEL operation driven by short electron bunches is studied. Under the assumption of a high quality resonator a parabolic equation for the evolution of electromagnetic pulse profile is derived. Based on an analytical theory describing the linear stage of generation a starting condition is determined. A structure of supermodes representing the sum of resonator eigenmodes with locked phases is found as well. It is demonstrated that due to waveguide dispersion FEL is able to generate not only for positive but also for negative cavity detuning. The computer simulation of a nonlinear regime taking into account electromagnetic pulse dispersion defines a stationary profile of electromagnetic pulse in good agreement with experimental results*,**. It is shown that regimes with periodic and chaotic self-modulation of the pulse profile are realized for considerable exceeding of the length of interaction region over the threshold. A superradiant (transient) regime of short pulse generation is found for small cavity detuning.
* Jeong Y. U., et al. Proc. of the 2004 FEL Conference, Trieste, Italy, 2004, P.667. ** Doria A., Bartolini R., Feinstein J. IEEE J. Quantum Electron., 1993, V.29, P.1428. |