A compact THz-driven electron gun

Novel all-optical terahertz (THz)-based accelerators promise to enable new science by providing ultrafast and bright electron bunches at a small footprint. While practical prototypes of THz-based devices have been demonstrated and have shown exceptional capabilities to accelerate and manipulate electron beams on sub-ps timescales, the development of practical THz-driven photoguns has lagged behind due to challenges associated with physical miniaturization and the high THz pulse energy required. This thesis significantly advances the development of such THz-driven guns by setting a dual focus: First, systematic parameter scans are performed on tilted pulse-front setups providing crucial insights into the non-collinear interactionlengths, parameter sensitivities and physics inherent to high-energy THz generation. In addition, spatio-temporal manipulation of the pump pulse is explored both experimentally and by simulations and found as viable tool to scale tilted pulse-front based THz sources to such energies required for the next generation of compact particle accelerators. Application of the findings resulted in robust extraction of THz pulses with energies up to 400 μJ while operating well below the optical damage threshold. Secondly, these setups are used in in three different experiments aimed at developing a practical compact THz-driven gun. The extraction of multi-keV electrons from a triggerable THz photogun is demonstrated for the first time, and the parameter space and resulting performance are explored. Subsequently, multi-layered structures are developed that extend the interaction between electrons and THz pulses. A novel single-sided pumped THz accelerator is tested and a segmented dual-sided pumped THz photogun is developed. Finally, the instrumentation for commissioning and scaling THz driven gun technology to energies beyond 100 keV, comparable to the performance of modern compact DC electron guns, is presented and discussed. This work represents a critical step in the development of practical all optical THzdriven electron guns and paves the way towards more compact accelerators with fs bunch durations, low emittance and orders of magnitude higher brightness to power future ultrafast electron diffraction experiments and compact X-ray sources