Top-level physics requirements and simulated performance of the MRSt on the National Ignition Facility

The time-resolving Magnetic Recoil Spectrometer (MRSt) for the National Ignition Facility (NIF) has been identified by the US National Diagnostic Working Group as one of the transformational diagnostics that will reshape the way inertial confinement fusion (ICF) implosions are diagnosed. The MRSt will measure the time-resolved neutron spectrum of an implosion, from which the time-resolved ion temperature, areal density, and yield will be inferred. Top-level physics requirements for the MRSt were determined based on simulations of numerous ICF implosions with varying degrees of alpha heating, P2 asymmetry, and mix. Synthetic MRSt data were subsequently generated for different configurations using Monte–Carlo methods to determine its performance in relation to the requirements. The system was found to meet most requirements at current neutron yields at the NIF. This work was supported by the DOE and LLNL.针对国家点火装置（National Ignition Facility, NIF）研发的时间分辨型磁反冲光谱仪（Magnetic Recoil Spectrometer, MRSt），已被美国国家诊断工作组认定为将重塑惯性约束聚变（inertial confinement fusion, ICF）内爆诊断范式的变革性诊断设备之一。MRSt将实现内爆过程的时间分辨中子能谱测量，借此可反推得到时间分辨的离子温度、面密度以及聚变产额。MRSt的顶层物理指标需求，是基于多组不同α加热程度、P2不对称性与靶丸混合程度的ICF内爆模拟结果确定的。后续研究团队通过蒙特卡洛方法为不同配置的MRSt生成了合成数据，以评估其是否满足既定指标需求。结果表明，在当前NIF装置的中子产额条件下，该系统可满足绝大多数指标要求。本研究得到了美国能源部（Department of Energy, DOE）与劳伦斯利弗莫尔国家实验室（Lawrence Livermore National Laboratory, LLNL）的资助。