Laser-driven neutron sources: principles, progress and prospects

With fast developments in ultra-short and ultra-intense lasers, a novel neutron source with high brightness, short pulse, and compact size—LDNS (laser-driven neutron source), can serve as a vital supplement to conventional neutron sources. With compactness and relatively low construction cost, LDNS offers considerable promise for a wide range of applications, including non-destructive material testing, neutron imaging, neutron resonance spectroscopy, and nuclear astrophysics.

LDNS has four major production mechanisms—beam–target neutron sources, photonuclear neutron sources, cluster neutron sources, and implosion neutron sources. Beam–target neutron sources represented one of the most widely investigated schemes for laser-driven neutron generation. Representative beam–target experiments demonstrated that single-shot neutron yields could reach the 10¹¹ neutrons per shot level in large-scale picosecond-laser experiments, highlighting the strong potential of this scheme for high-flux pulsed neutron production. Meanwhile, considerable efforts have been devoted to improving neutron beam directionality, temporal characteristics, and overall source stability. In parallel, progress was also made toward high-repetition-rate operation: a beam–target neutron source driven by the Advanced Laser Light Source was demonstrated at 0.5 Hz, producing broadband neutrons with an average flux on the order of 10⁵ n/s, which marks a meaningful step toward practical high-repetition-rate laser-driven neutron applications. Photonuclear neutron sources driven by intense laser pulses saw significant progress in yield and beam quality. Recent advances included achieving neutron yields up to 1.4×10¹⁰ n/shot via laser-driven electron acceleration and optimized converter targets. Notably, micro-structured target designs substantially enhanced laser-to-neutron conversion efficiency. Beyond yield enhancement, precise control of source parameters was demonstrated, including the generation of a compact 500 μm source size with a ~36 ps pulse duration for high-resolution imaging. Furthermore, high-repetition-rate operation at 100 Hz with 50 ps pulses was realized, enabling improved fast neutron resonance spectroscopy. For cluster neutron sources, current development focused on coupling high-repetition-rate lasers with continuous fluid targets to achieve high average neutron fluxes. Regarding implosion neutron sources, the research paradigm transitioned from basic spherical convergence validation to multi-physics synergistic optimization. Experiments showed that spherically convergent plasma fusion improved implosion stability. Furthermore, introducing external magnetization combined with laser preheating effectively suppressed thermal conduction losses and enhanced energy coupling.

We also systematically review the diagnostic techniques for key parameters of laser-driven neutron sources, including neutron energy spectrum, yield, angular distribution, source size, and pulse width. The neutron time-of-flight (nTOF) method remained the gold standard for energy spectrum measurement, while bubble detectors (with emerging AI-assisted bubble counting) and activation foils were widely used for yield and angular distribution characterization. Knife-edge and coded aperture imaging techniques were employed for source size measurement. However, direct measurement of neutron pulse width remained an unsolved challenge. Streak cameras and low-gain avalanche detectors were both candidate detectors for the pulse width diagnostic system of LDNS. Researchers explored and verified prospects and feasibility of LDNS for applications in different fields via simulations and experiments. Recent breakthroughs saw a transition from multi-shot data accumulation to robust single-shot resonance analysis, alongside the emergence of table-top, high-repetition-rate systems (up to 100 Hz). These advancements facilitated the quantitative determination of isotope areal densities and real-time assays of nuclear materials, providing a mobile and cost-effective alternative to large-scale spallation facilities. Simultaneously, neutron imaging advanced through the integration of flash radiography and dual-energy techniques. LDNS-based imaging excelled in capturing fast-transient phenomena and distinguishing light elements, such as hydrogen within heavy metallic structures, where conventional X-rays often fail. The development of dual-energy fast neutron imaging and high-gain, nanosecond-gated detector systems further enhanced material discrimination and signal-to-noise ratios even under low-flux conditions. Collectively, these technological leaps established LDNS as a versatile, on-site complement to centralized neutron sources, particularly for high-speed fluid dynamics, hydrogen energy infrastructure inspection, and non-destructive testing in extreme environments.

In summary, this paper reviews the historical development and recent progress of LDNS, its diagnostic techniques, and substantial potential for both fundamental research and practical applications. Achieving high repetition-rate operation for a long period is indispensable for LDNS to obtain steady neutron beams needed in actual applications. This not only requires laser systems and targets to operate in high-repetition-rate mode, but also faces challenges across multiple aspects, such as constructing radiation shielding for mobile LDNS and solving laser system pointing stability issues. With the development of various technologies, LDNS has broad application prospects across multiple fields.