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Laser-driven radiation sources: towards ultrafast nanodosimetry Jonathan Philip Kennedy (23656501) PUREID: 616899673 laser plasma laser driven ion acceleration high harmonic generation This thesis explores the unique advantages of laser-driven radiation sources through a combination of simulation and experimental work, focusing on some of nature’s fastest dynamics. When a relativistic laser interacts with a smooth solid target it can generate coherent bursts of attosecond XUV light. However, a train of attosecond pulses is generated due to the multiple cycles of the driving laser. A single attosecond pulse must be isolated to use this source in applications. The non-collinear gating scheme is investigated in this thesis via three- dimensional and two-dimensional particle-in-cell simulations. This method demonstrated the effective isolation of bright attosecond light pulses. Unlike other gating methods, this generates isolated attosecond pulses without the need for spectral filtering, thus preserving the pulse’s intensity and coherence.<br><br>Next, multi-MeV energy protons can be generated via target normal sheath acceleration when a relativistic laser interacts with a thin foil target. This laser-driven source of protons has ultra-short picosecond durations. Unfortunately, they also have broadband energies and large divergences. This thesis investigates the use of helical coils in generating laser- driven focused, quasi-monoenergetic ion beams. Using an optical streaking method, resulted in the measurement of a proton bunch duration of τFWHM = 26 ± 6 ps and an energy spectrum with a mean energy of E = 7.6 MeV and bandwidth of ∆EFWHM = 0.78 MeV. This represents the shortest directly measured duration of a proton bunch far from the source, offering a novel approach for various applications and providing new insights into ion damage in different materials.<br><br>Finally, the observation of GHz frequency oscillations in LiNbO3 crystals induced by laser-driven radiation was studied. By driving LiNbO3 with laser-driven radiation, ultrafast refractive index changes were launched that propagate at ∼20% the speed of light. This propagation rotates the polarisation of the incident probe light. Controlling these oscillations resulted in a 60 ps polarisation switch. This observation paves the way for developing a laser-driven, jitter-free Pockels switch. These findings, collectively enhance our understanding of laser-driven radiation sources. They open exciting new avenues for research and possible technological applications. 2026-10-01T16:31:50Z Text Thesis 10.17034/32640363.v1 https://figshare.com/articles/thesis/Laser-driven_radiation_sources_towards_ultrafast_nanodosimetry/32640363 All Rights Reserved