This paper deals with time-of-flight diagnostics of relatively short neutron pulses from tens to hundreds of nanoseconds. The aim is to determine the time evolution of energy spectra. The diagnostic setup consists of several neutron detectors placed in one direction at different distances. This approach is improved by placing additional detectors in the opposite direction. How the reconstruction method works with two opposite directions is explained in this paper. Improvement is limited to the deuterium fusion reaction D(d,n)3He. However, the principles described here could be applied in various fusion experiments. The advantage of our approach is not only better reconstruction but also the partial elimination of the influence of scattered neutrons. The described method was applied in the processing of data from fusion experiments in the PF-1000 facility and provided time evolution of the neutron energy spectra with energy resolution of 50 keV. In these plasma-focus experiments, results indicated a non-thermal production mechanism of the predominant part of the neutrons produced.
本论文涉及对持续时间从数十到数百纳秒的相对较短中子脉冲的飞行时间诊断。目标是确定能量随时间的演化。诊断系统由多个中子探测器组成，它们沿同一方向放置在不同距离处。通过在对侧方向增设探测器，该方法得到了改进。本文阐述了利用两个相反方向进行重建的方法。改进仅限于氘聚变反应D(d,n)³He。然而，所述原理可应用于各种聚变实验。本方法的优势不仅在于重建效果更佳，还在于能部分消除散射中子的影响。所述方法已应用于PF-1000装置上聚变实验的数据处理，并以50 keV的能量分辨率给出了中子能谱的时间演化。在这些等离子体焦点实验中，结果表明所产生的主要中子部分源于非热力学机制。