Parametric studies of free-electron laser nonlinear ponderomotive trapping buckets

Experimental and computational studies of free-electron lasers (FELs) operating at high input powers have been undertaken. These studies constitute a novel method of investigating saturation and trapping effects in free-electron lasers. Experiments and simulations show that when the input radiation power is increased to levels comparable to output power, the energy that maximizes the FEL gain shifts upwards. This effect is directly related to the height of the FEL ponderomotive trapping bucket (see J.S. Wurtele et al., 1990). By parametrically surveying the extent of this energy shift the authors observe the nonlinear trapping bucket phenomenon