146 / 2025-03-15 20:36:22

Research Progress in Nuclear Diagnostics Technology for High-Energy-Density Physics Experiments at Laser Facilities

Nuclear Diagnostics,,inertial confinement fusion

The use of high-power lasers to drive the implosion compression of deuterium-tritium fuel-filled fusion targets confines high-temperature, high-density fuel plasmas, resulting in fusion ignition and sustained burn reactions. Nuclear diagnostics primarily focus on measuring the products within the fusion reaction zone. The information provided characterizes the overall performance of the implosion, reflecting the final state of fuel heating and compression, which collectively embodies the integrated physical effects of the entire implosion process. Nuclear diagnostic systems are mainly used to measure the physical state of the fusion reaction zone, inferring the state of the fuel capsule during the stagnation phase by analyzing the energy spectra, temporal profiles, and spatial distributions of fusion reaction products. Based on the Shenguang series laser facilities, research in nuclear diagnostics has developed methods for neutron flux, neutron energy spectra, and temporal diagnostics, enabling the measurement of key parameters such as neutron yield, ion temperature, neutron bang time, and hot spot areal density. Additionally, the exploration of diagnostic techniques such as neutron imaging and gamma-ray diagnostics has played a significant role in physical experiments. The stagnation phase of the implosion is extremely short (hundreds of picoseconds), and the fusion reaction region is small (hundreds of micrometers), requiring diagnostics of fusion product spatiotemporal distributions to possess extremely high spatiotemporal resolution. However, fusion products such as neutrons and gamma rays exhibit strong penetration and long mean free paths in materials, resulting in low detection efficiency for diagnostic systems. Furthermore, system shielding is challenging, and high neutron yields make the diagnostics susceptible to environmental scattering background noise. The development of nuclear diagnostic technologies for laser facilities still faces significant challenges in diagnostic methods, measurement unit device fabrication, equipment performance, and data analysis techniques.