Methods for the Optimization of a Tapered Free-Electron Laser

In a free-electron laser (FEL), the technique of wiggler tapering enables the sustained growth of radiation power beyond the initial saturation. With the goal to develop an X-ray FEL in the terawatt power regime, it is important to utilize this technique and optimize the taper profile, giving the wiggler parameter as a function of the distance along the wiggler line. This work examines two methods of optimization, which are based on the theoretical analysis by Kroll, Morton and Rosenbluth (KMR). Using the numerical simulation code GENESIS, the methods are applied to a case for the possible future FEL at the MAX IV Laboratory in Lund, Sweden, as well as a case for the LCLS-II.
Proceedings of the 5th Int. Particle Accelerator Conf., IPAC2014, Dresden, Germany