Hydrogen boron fusion in confined geometries

Abstract High-energy, short-pulse laser-driven proton–boron (p– 11 B) fusion has attracted growing interest due to its aneutronic character and potential for clean energy generation. In this study, we report on two experimental campaigns carried out at the LFEX laser facility using petawatt-class laser systems (energy $\sim$ 1.2–1.4 kJ, pulse duration 2.7 ps, peak intensity $\sim$ (2–3) × 10 19 W/cm 2 ). The experiments explored the influence of complex target geometries – including spherical, cylindrical and wedge-shaped configurations – on α-particle yield. Our results demonstrate that spherical targets can enhance α-particle production by up to two orders of magnitude compared to planar targets of identical composition and also lead to a noticeable shift of the α-particle energy spectrum toward higher values. Furthermore, we implemented a novel diagnostic technique for unambiguous α-particle detection using a CR-39 detector integrated into a Thomson parabola spectrometer. Particle-in-cell simulations performed with the Smilei code provide additional insight into the role of self-generated magnetic fields in modulating particle dynamics. These simulations highlight the critical interplay among target geometry, confinement effects and fusion efficiency. Overall, our findings underscore the potential of optimized target designs to significantly enhance fusion yield and α-particle output in p– 11 B fusion, with promising implications for the development of laser-driven α-particle sources and advanced clean energy concepts.