Free electron laser pulse characterization by THz streaking

Abstract

The goal of this dissertation was to investigate a reliable single-shot pulse duration diagnostic tool for the pulse duration and wavelength range delivered at the Free Electron LAser of Hamburg (FLASH). At Self-Amplified-Spontaneous-Emission-based free-electron lasers (FELs), the radiation parameters - duration, arrival time, energy, spectrum, and spatial distribution - differ for each pulse. A dedicated single-shot diagnostic tool for each parameter is therefore essential in order to interpret the experimental data on a pulse-to-pulse basis.This work summarizes the effort to realize a temporal diagnostic tool using the streaking technique by building a terahertz (THz) "streak camera". The setup was prepared and calibrated, and various pulse duration measurements with different experimental settings were performed in order to explore and validate the application range of the streaking method. The aspects limiting the temporal resolution using the commissioned streaking setup were characterized experimentally. The pulse duration measurements were analyzed using classical and quantum mechanical streaking theory models.Furthermore, a deep statistical study on the SASE fluctuations was realized using single-shot measurements of various radiation parameters. Scaling laws were derived using theoretical simulations and the measured data. This analysis enabled the intrinsic statistical SASE fluctuations to be disentangled from accelerator-based fluctuations and measurement uncertainties