Development of Sophisticated Fusion Neutron Measurement System Based on Optical Fiber Sensing

本研究提出了一种基于光纤传感技术的精密聚变中子测量系统的新概念，该系统利用不同特性的有机光纤和闪烁体组成的网络，从网络组件的光传播时间、光吸收率和发光点所对应的立体角，三维同时测量入射到不同特性的有机光纤和闪烁体网络中的聚变中子沉积能量和位置。我们设计并部分制造了原型系统，用于实验展示它们的基本性能。本文的主要研究成果如下：(1)利用多级塑料闪烁光纤与一对位置敏感光电倍增管相结合，设计了一种简单紧凑的聚变中子测量系统，可以同时获得中子的能量和入射方向（或分布）。(2)将有机液体闪烁体与波长移动光纤相结合，设计了一种大灵敏度的聚变中子图像传感器，并进行了实验验证。(3)开发了仿真程序，根据实验结果估计上述探测器的性能，并用于改进和/或优化探测器系统的设计。(4)这些结果已应用于类似iter的聚变等离子体诊断的概念设计建议，特别是聚变中子剖面监测仪的新概念。

The purpose of this study is to create a new concept of sophisticated fusion neutron measurement system based on optical fiber sensing technique, where deposited energy and position of fusion neutrons incident onto a network consisting of organic optical fibers and scintillators with different characteristics are measured three-dimensionally and simultaneously from light propagation time, light absorption rate and solid angle subtended by light emission point in the network components.We have designed and partially manufactured the prototype system for experimental demonstration of their basic performances.Main achievements in this study are summarized as follows :(1)A simple and compact fusion neutron measurement system which can obtain energy and incident direction (or profile) of neutrons simultaneously has been devised and experimentally demonstrated by using multistage plastic scintillating fibers combined with a pair of position sensitive photomultipliers.(2)A fusion neutron image sensor with a large sensitive area has been devised and experimentally demonstrated by combining organic liquid scintillator with wavelength shifting fibers.(3)The simulation program has been developed to estimate the above detector performance based on the experimental results and used to improve and/or optimize the detector system design.(4)These results have been applied to conceptual design proposals for an ITER-like fusion plasma diagnostics, in particular for new concept of fusion neutron profile monitors.