Mechanisms behind the surprising observation of supra-thermal ions in NIF’s fusion burning plasmas  

激光聚变燃烧等离子体的大角度碰撞动理学数值模拟

作　　者：Yuhan Xue Dong Wu Jie Zhang 薛宇涵;吴栋;张杰

机构地区：[1]Key Laboratory for Laser Plasmas and Department of Physics and Astronomy,Collaborative Innovation Center of IFSA(CICIFSA),Shanghai Jiao Tong University,Shanghai 200240,China [2]Institute of Physics,Chinese Academy of Sciences,Beijing 100190,China

出　　处：《Science Bulletin》2025年第3期359-364,共6页科学通报(英文版)

基　　金：supported by the Strategic Priority Research Program of Chinese Academy of Sciences(XDA250010100 and XDA250050500);the National Natural Science Foundation of China(12075204);Shanghai Municipal Science and Technology Key Project(22JC1401500)。

摘　　要：Although ignition had been achieved at the National Ignition Facility(NIF),recent observations of the experiments indicate novel physics that beyond theoretical predictions emerge,e.g.,the neutron analysis of experiments has revealed deviations from the Maxwellian distributions in ion relative kinetic energies of burning plasmas,with the surprising emergence of supra-thermal deuterium and tritium(DT)ions that fall outside the predictions of macroscopic statistical hydrodynamic models.Via our newly developed hybrid-particle-in-cell code,incorporating the newly-proposed model of large-angle collisions,we infer that that this could be attributed to the increased significance of large-angle collisions among DT ions andα-particles in the burning plasma.Extensive and unprecedented kinetic investigations into the implications of large-angle collisions in the burning plasma have yielded several key findings,including an ignition moment promotion by~10 ps,the presence of supra-thermal ions below an energy threshold,and approximately twice the expected deposition ofα-particles densities.The rationality of our findings is confirmed through the congruency between the neutron spectral moment analyses conducted by the NIF and our kinetic simulations,both highlighting progressively widening disparities between neutron spectral moment analyses and hydrodynamics predictions,which becomes more pronounced as the yield increases.Our kinetic simulations with large-angle collisions not only provide novel insights for experiment interpretation but also open new research opportunities for the largely unexplored regime of the nuclear burning plasmas,which are distinguished by their exceptionally high energy densities and hold immense potential for illuminating the intricate physics that underpins the evolution of the early universe.

关 键 词：lon kinetics Supra-thermal ions Large-angle collisions Non-equilibrium ignition Inertial confinement fusion Burning plasmas 

分 类 号：TL612[核科学技术—核技术及应用]