Machine design and electron beam control of a single-pass linac for free electron laser: the FERMI@Elettra case study

PhD ceremony: Mr. S. Di Mitri, 11.00 uur, Aula Academiegebouw, Broerstraat 5, Groningen

Dissertation: Machine design and electron beam control of a single-pass linac for free electron laser: the FERMI@Elettra case study

Promotor(s): prof. P.H.M. van Loosdrecht, prof. S. Brandenburg, prof. F. Parmigiani

Faculty: Mathematics and Natural Sciences

A strong need has emerged over the last few years for a source of radiation with extremely high brilliance, close to full coherence, a bandwidth approaching the Fourier limit and a stable and well characterized temporal structure in the femtosecond domain. Such a source is the single-pass Free Electron Laser (FEL) that, due to Doppler frequency up-shifting of emitted radiation by relativistic electrons, is particularly well-suited to generate short wavelength X-ray pulses with peak brilliance many orders of magnitude higher than that generated in modern synchrotrons. The FEL high brilliance, high intensity and shot-to-shot stability strongly depends on the electron beam source. Delivering a high quality electron beam and machine flexibility to serve a broad range of potential applications imposes severe requirements on the final electron beam parameters and the machine design. To meet these requirements, the need of a linac design based on extensive studies of possible perturbations that may affect the electron beam dynamics, of means to correct them and of parameter optimization has emerged. Because of the special sensitivity of the FEL generation to the electron beam emittance, relative energy spread and trajectory control, this Thesis has focused on the design strategies to control these parameters. Some aspects of the study have been developed for the FEL scheme known as harmonic generation. The general principles have been applied, for a quantitative analysis, to the FERMI@Elettra FEL. Some experimental results of the recent FERMI commissioning have been discussed and compared with the model predictions.