High-resolution measurements of the DT neutron spectrum using new CD foils in the Magnetic Recoil neutron Spectrometer (MRS) on the National Ignition Facility

The Magnetic Recoil neutron Spectrometer (MRS) on the National Ignition Facility (NIF) measures the DT neutron spectrum from cryogenically layered Inertial Confinement Fusion (ICF) implosions. Yield, areal density, apparent ion temperature and directional fluid flow are inferred from the MRS data. This paper describes recent advances in MRS measurements of the primary peak using new, thinner, reduced-area deuterated plastic (CD) conversion foils. The new foils allow operation of MRS at yields 2 orders of magnitude higher than previously possible, at a resolution down to ~200 keV FWHM.

美国国家点火装置（National Ignition Facility，NIF）搭载的磁反冲中子谱仪（Magnetic Recoil neutron Spectrometer，MRS），可对低温层状惯性约束聚变（Inertial Confinement Fusion，ICF）内爆过程产生的氘氚（DT）中子能谱进行测量。研究人员可从MRS的实测数据中推导出聚变产额、面密度、表观离子温度与定向流体流动参数。本文介绍了采用新型超薄减面积氘代塑料（deuterated plastic，CD）转换箔开展初级峰MRS测量的最新研究进展：新型转换箔可使MRS的可测产额较此前提升两个数量级，且分辨率可达约200 keV半高全宽（Full Width at Half Maximum，FWHM）。