Alpha-particle generation via laser-driven proton-boron fusion

Boron ion energies of up to 2 MeV/u were achieved, but contributed negligibly to the fusion yield due to low flux and higher stopping power. Proton stopping-power calculations using the dedx-erpa code showed significantly reduced stopping power at plasma temperatures above a few hundred eV, which is suggested as the explanation for the higher-than-expected experimental yields.<br>In a second study, 2D PIC simulations explored the generation of beamed alpha-particle sources via p11B fusion.

A high-intensity (2.5×1021 W/cm2) circularly polarised pulse irradiated a double-layer target comprising a near-critical-density boron layer on a solid-density hydrocarbon foil. A density scan identified optimal conditions at 11 nc in the boron foam, accelerating boron ions within a 30° cone up to 35 MeV/u via hole-boring radiation-pressure acceleration. Below 11 nc, the onset of relativistic transparency degraded ion acceleration and beam divergence.

A focal position scan showed that beam divergence could be reduced below 9° at the cost of lower maximum energy by generating a more uniform hole-boring front. Nuclear reactions included in the PIC simulations demonstrated that driving fusion with energetic boron ions, rather than protons, boosts alpha-particle energies by approximately 7-fold to ~40 MeV, suitable for medical radioisotope production.<br><br><i>Thesis is embargoed until 31 July 2027.</i><br>