Speaker
Description
In the framework of laser-driven nuclear fusion research, we conducted a comprehensive experimental campaign at the Prague Asterix Laser System (PALS) in 2024 to investigate the proton–boron (p–11B) fusion reaction. The primary objective was to study the acceleration of high-energy protons and the subsequent generation of alpha particles through nuclear fusion reactions with boron targets. High-intensity, high-energy laser pulses were used to irradiate both boron-containing and boron-free primary targets, enabling a detailed study of proton acceleration and alpha particle production in different target compositions. A natural boron secondary target was employed in a pitcher–catcher configuration to allow energetic protons from the primary target to induce the ¹¹B(p,α)2α fusion reaction. Additionally, the in-plasma fusion configuration was explored, in which proton–boron fusion occurs directly within the laser-produced plasma, aiming to maximize alpha particle yields and study their production mechanisms under extreme plasma conditions.
The PALS iodine laser, operating at 1315 nm with sub-nanosecond pulse duration and intensities exceeding 10¹⁶ W/cm², provided the driver for proton acceleration. The experimental setup incorporated an advanced diagnostics suite, including CR-39 track detectors positioned covered with aluminum filters to reconstruct proton and alpha energy spectra, a matrix configuration combining CR-39 and diamond detectors integrated into a time-of-flight (TOF) system for real-time particle energy measurements, and activation detectors composed of various materials for precise quantification of nuclear reactions. Interferometric measurements with femtosecond and nanosecond resolution were also used to characterize the plasma density and its temporal evolution during laser-target interaction.
Analysis of the TOF and Thomson Parabola (TP) data revealed maximum proton energies of 5.7 MeV and 5.5 MeV, respectively, confirming efficient proton acceleration capable of triggering the ¹¹B(p,α)2α fusion channel. The new generation of targets showed a significant increase in the total number of alpha particles detected in the in-plasma fusion regime, providing valuable insights into the mechanisms of laser-driven nuclear fusion and highlighting the potential of high-intensity laser systems for generating high-current, high-energy alpha particle beams.
Looking forward, a new experimental campaign is scheduled from 24 November to 19 December 2025, where advanced diagnostic configurations will be employed to further improve the precision and accuracy of alpha particle measurements. This campaign will deploy refined CR-39 and diamond matrix configurations, enhanced TOF systems, and activation detectors with carefully selected materials to optimize sensitivity and resolution for both alpha and proton detection. The secondary boron target will be irradiated under controlled conditions to produce high-yield alpha particles, allowing detailed investigation of particle production, energy distribution, and angular emission. These experiments aim to generate high-fidelity data to benchmark theoretical models of laser-driven p–B fusion, providing critical input for designing future high-yield laser fusion experiments.
The broader vision of this fusion project is to contribute directly to European Inertial Confinement Fusion (ICF) initiatives. Leveraging experience from PALS and the I-LLucia laser system, the project seeks to apply optimized laser-target interaction schemes, advanced diagnostics, and high-precision nuclear measurements to future ICF experiments in Europe. This approach positions the team to play a key role in next-generation ICF campaigns, particularly in maximizing alpha particle yields, studying laser-driven proton and alpha acceleration, and understanding plasma-driven fusion mechanisms under controlled conditions.
Overall, the results from PALS 2024, combined with the upcoming PALS 2025 campaign, demonstrate the feasibility of using high-intensity laser systems to generate high-energy alpha particles via proton–boron fusion. These efforts will not only deepen our understanding of particle acceleration and nuclear reaction mechanisms in laser-produced plasmas but also lay the groundwork for future contributions to European ICF projects. By integrating experimental expertise, target development, and advanced diagnostic techniques, the project aims to support the development of high-yield, laser-driven fusion systems and strengthen Europe’s position in the global ICF research landscape.