Model-based optimization of tapered free-electron lasers

作者：Mak Alan^*; Curbis Francesca; Werin Sverker

来源：Physical Review Special Topics - Accelerators and Beams, 2015, 18(4): 040702.

DOI：10.1103/PhysRevSTAB.18.040702

The energy extraction efficiency is a figure of merit for a free-electron laser (FEL). It can be enhanced by the technique of undulator tapering, which enables the sustained growth of radiation power beyond the initial saturation point. In the development of a single-pass x-ray FEL, it is important to exploit the full potential of this technique and optimize the taper profile a(w)(z). Our approach to the optimization is based on the theoretical model by Kroll, Morton, and Rosenbluth, whereby the taper profile a(w)(z) is not a predetermined such as linear or exponential) but is determined by the physics of a resonant particle. For further enhancement of the energy extraction efficiency, we propose a modification to the model, which involves manipulations of the resonant particle's phase. Using the numerical simulation code GENESIS, we apply our model-based optimization methods to a case of the future FEL at the MAX IV Laboratory (Lund, Sweden), as well as a case of the LCLS-II facility (Stanford, USA).

• 出版日期2015-4-23