THRESHOLD CONDITION AND SATURATION MECHANISMS FOR THE SUPER-ACO STORAGE-RING FREE-ELECTRON LASER

The Super-ACO free electron laser is currently operating in the visible spectral range; the laser also operated in the near UV. Threshold conditions were determined for various configurations. These are in agreement with the theoretical predictions based on the assumption that the optical gain evolution is governed by the energy spread mechanism. Dynamical studies at a microtemporal (ps range) and macrotemporal (ms range) scale were performed for higher values of the gain over losses ranging from 1 to 3. Those experiments seem to indicate that the laser induced energy spread plays a minor role in the saturation mechanism. Dynamical evolution and saturation properties seem to be ruled by another mechanism, except when the laser is operating close to the threshold condition.