Evolution of long pulses in a tapered wiggler free-electron laser
The evolution of a long pulse in a tapered wiggler free electron laser is studied by numerical solution of the 1-D theoretical model for a realistic set of magnet, electron beam, and optical resonator parameter values. Single pass gain curves are calculated for low and high light intensity. It is found that an initial, low amplitude, incoherent pulse grows into a coherent pulse whose growth rate agrees with the calculated small signal gain. The transient evolution of coherent pulses is calculated for several different cavity length detunings, and a quasi steady state desynchronism curve is given. The frequency changing behavior of the optical pulse is shown to occur through sideband generation associated with synchrotron oscillations. Pulse evolution with an ideal intracavity high pass optical filter is calculated.
NASA STI/Recon Technical Report N
- Pub Date:
- Free Electron Lasers;
- Wiggler Magnets;
- Optical Filters;
- Lasers and Masers