UC Irvine

This thesis presents a computational study on the propagation effects of space-time coupled laser beams, their interaction with thin hydrogen foils, and the resulting effect on accelerated protons. Laser-plasma simulations are typically done using particle-in-cell codes where analytic descriptions of Gaussian beam propagation, that make assumptions on the frequency dependent nature of ultrashort pulses, are used. A code was developed using Fourier propagation techniques that accurately describes the diffractive effects of arbitrary focused fields which was implemented into a particle-in-cell code. The accurate model shows varying laser-matter interaction dynamics compared to the approximated fields. The Fourier propagation code also enables the study of focused spatially chirped beams generated from the output of a single-pass, two-grating compressor. These fields have a space-time coupling that exhibit a pulse front tilt and pulse front curvature depending on the gratings used to generate them. When focused onto a hydrogen target, enhanced collimation and increased proton energies beyond that of a Gaussian beam are possible. Axisymmetric extensions of these space-time fields enable the generation of highly collimated proton jets. The results of this thesis provide insight into the effects accurate laser modeling and space-time couplings have on laser accelerated ions.