Resistive Guiding of Fast Electrons in High-Intensity Laser-Plasma Interactions

This thesis presents the first experimental investigations into resistive guiding of fast electrons using conically structured targets. Two experiments are presented in which a combination of experimental diagnostics and simulations are used to examine the performance of resistively generated magnetic fields in reducing the fast electron divergence. A critical aspect of this work is the deployment of a novel front surface imaging system to determine the location of the laser-target interaction.

Significant rear surface heating is inferred in both experimental campaigns using shadowgraphy and one-dimensional hydrodynamic simulations in HYADES. Conically structured targets are shown to reach temperatures of up to 200eV; a significant enhancement at greater depth and reduced laser energies than results reported in the literature. Analysis of the laser focal spot and three-dimensional hybrid simulations in ZEPHYROS show how an astigmatic beam with significant energy outside of the main peak can enhance the confinement of electrons and improve the volumetric heating of the target.

Proton diagnostics are used to determine the performance of conically structured targets. Significantly, an enhancement in peak proton energy is recorded for cones with opening half-angles of approximately 10 degrees. We suggest a mechanism underpinning these results and how the ability of the cone targets to reduce the fast electron divergence is sensitive to the specific target geometries implemented on the experiments.

The fast electron beam that escapes the rear surface is observed to filament using a combination of image plate (IP) and coherent transition radiation (CTR) diagnostics. Three-dimensional hybrid simulations using ZEPHYROS present similar filamentation and show how the observation of the break-up of the electron beam does not significantly inhibit the resistive guiding mechanism.