image: The 3-D current density and 2-D magnetic fields during the pinch simulation. In the 3D image, the red color represents positive current, while the blue color represents negative current. The 2D image illustrates the magnetic field. The x-positive direction aligns with the laser propagation and the axial direction of the nanowire, whereas the y and z directions correspond to the radial directions of the nanowire. When irradiated by the ultrashort, high-intensity laser pulses, the atoms inside the wire undergo field ionization. The ionization process leads to a considerable potential difference on the surface of nanowire. This potential disparity is balanced by a significant return current flowing across the nanowire's surface, maintaining quasi-neutrality. Due to the extremely high current density, the induced magnetic field around the nanowire is also significant. This quasi-static magnetic field exerts a J×B force on both inner and outer current (electrons) of the nanowire.
Credit: Guo-Qiang Zhang
Extreme Deuterium Density
The study leverages petawatt-class lasers to induce the Z-pinch effect in deuterated polyethylene nanowires. This process compresses deuterium ions to densities exceeding 1025 cm-3, creating a micro-scale environment where nuclear fusion reactions produce femtosecond-duration neutron pulses.
Revolutionizing Neutron Generation
Using advanced Particle-in-Cell (PIC) simulations, the team demonstrated that a single 300 nm nanowire irradiated by a 60-fs laser pulse achieves a peak neutron flux of 1026 cm-2s-1. The compression phase, lasting just 10 femtoseconds, generates radial ion fluxes of 1034 cm-2s-1, enabling high-yield deuterium-deuterium (D-D) and deuterium-tritium (D-T) fusion reactions. D-T reactions produce over tenfold higher neutron yields compared to D-D, with simulations predicting over 106 neutrons per pulse in optimized nanowires.
Bridging Astrophysics and Laboratory Research
The extreme conditions potential for generating neutron-rich environments, critical for studying r-process nucleosynthesis. “This method bridges the gap between astrophysical phenomena and controlled laboratory experiments,” explains Putong Wang. “The femtosecond-scale neutron bursts also enhance Time-of-Flight measurements, crucial for nuclear data accuracy.”
Technological and Scientific Implications
Beyond astrophysics, the technique’s ultra-short pulses and microscopic spatial resolution (30 nm×30 nm) open avenues for materials science and neutron imaging. The team highlights potential applications in neutron or proton capture reactions and compact neutron sources for industrial and security sectors.
Future Directions
The researchers plan to explore instabilities in Z-pinch dynamics and optimize target parameters for diverse nuclear reactions. “By refining laser parameters and nanowire designs, we aim to push neutron fluxes closer to astrophysical extremes,” says Putong Wang. The complete study is accessible via DOI: 10.1007/s41365-025-01738-9.
Journal
Nuclear Science and Techniques
Method of Research
Computational simulation/modeling
Subject of Research
Not applicable
Article Title
Laser-driven micro-pinch: a pathway to ultra-intense neutrons
Article Publication Date
2-May-2025