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oai:figshare.com:article/32805683 2026-10-01T16:14:08Z portal_1172 item_type_8 month_year_10_2026

Alpha-particle generation via laser-driven proton-boron fusion Daniel P. Molloy (24292862) PUREID: 685728891 Fusion ion acceleration laser driven ion acceleration proton boron alpha particles radiation pressure acceleration hole boring The proton-boron-11 (p¹¹B) fusion reaction is an aneutronic process that produces three alpha particles and releases 8.7 MeV of energy entirely through charged particles, making it an attractive alternative to deuterium-tritium fusion for both energy production and as a source of energetic alpha-particle beams. This thesis presents experimental and numerical investigations into driving p¹¹B fusion using high-intensity laser systems. Two laser-driven p¹¹B fusion experiments were performed using the TARANIS laser at QUB (10 J, 800 fs, peak intensity >1019 W/cm2). A range of novel boron- and hydrogen-rich targets were irradiated, with protons and ions characterised using Thomson parabola spectrometer, time-of-flight, and CR-39 detectors. Alpha-particle fluences up to 5×108 sr-1 were measured, comparable, when normalised by laser energy, to the highest reported yields performed at other laser facilities. Complementary 2D FLASH radiative-hydrodynamic and WarpX particle-in-cell simulations modelled the interaction, showing proton generation up to 4 MeV, sufficient to drive p11B 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. 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. Thesis is embargoed until 31 July 2027. 2026-10-01T16:14:08Z Text Thesis 10.17034/32805683.v1 https://figshare.com/articles/thesis/Alpha-particle_generation_via_laser-driven_proton-boron_fusion/32805683 All Rights Reserved Open Access after 2027-07-31