新型光纤瞬态辐照效应研究

The demand of optical fibers for data transmission in the high radiation environment is large. They have a number of well-known advantages with respect to the traditional forms of data link, such as their electromagnetic immunity, low weight and high bandwidth. Recently，the research on novel optical fibers,such as large pure silica core optical fiber with step index profile and random hole optical fiber (RHOF) were the main trend. However，because of the lack of research on transient radiation effects,the applications of these optical fibers becomes difficulty in pulsed nuclear radiation fields diagnostics. .In this research work,we will develop a method of measuring transient radiation effects in large pure silica core optical fiber and random hole optical fibers (RHOF). The tecnology of radiation shield and radiation resistant will be studied by theoretic simulation and experiments. A large number of scientific researches on transient radiation effects of pulse gamma/X-ray and nuetron in these optical fibers will be made. These research contents include some the following : (1) the time dependant behavior of radiation-induced loss, the relation between loss level with radiation dose, dose rate and spectra of the optical signals;(2) the time dependence of the luminescence, luminescence spectrum ,the relation between luminescence level with radiation dose, dose rate.These problem are important for utilization of fiber optic in radiation diagnostics. Through reseaching and solving these problem,a novel detecting technology will be devoloped for pulse radiation field measurement,pulse plasma diagnostic,and inertial confinement fusion diagnostic.

由于高带宽和强抗电磁干扰等优点，光纤被广泛地用于辐射场信号传输和探测。在高能脉冲辐射环境中，光纤辐照效应是影响光纤传输系统和测量系统性能的重要因素，目前对大芯径纯石英、随机孔隙光子晶体新型光纤的瞬态辐照效应还缺乏深入的研究和认识，给脉冲辐射场应用光纤技术进行定量化测量造成了困难，也严重限制了新型光纤辐射探测技术的发展。.本项目拟对大芯径纯石英光纤、光子晶体光纤的脉冲伽马/X射线瞬态辐照效应进行研究，建立光纤瞬态辐照效应的实验研究方法，结合理论模拟研究光纤的辐射屏蔽和抗辐射加固技术，研究给出辐照效应随总剂量、剂量率、辐射源种类的变化规律，研究分析光纤辐照效应的时间特性与光谱特性。研究目的是解决新型光纤在脉冲辐射场中面临的重要问题，为开展用于地面核爆诊断、实验室脉冲辐射源诊断用的新型光纤探测系统提供技术参考，具有重要的意义和应用价值。

该项目的主要目标针对一些新型的大芯径紫外传输光纤和透紫光纤开展辐照效应研究，研究光纤在稳态和脉冲辐射源激发下的光纤辐致损耗和发光，建立有效的定量化测试方法，研究蓝紫区光波段在受辐照光纤中的传输特性，为构建光纤抗辐照和发展应用提供技术支持。.针对以上课题目标，课题组主要完成以下工作：(1) 建立可分离测量和评估光纤辐照损耗和发光效应的测试方法和测量系统。基于脉冲装置实验，研究了光电倍增管不同电压下非线性响应及非线性校正方法，建立了宽动态、高灵敏的测量技术及系统。(2) 在稳态60Co装置和“晨光号”脉冲装置上开展0.2 mm、0.4 mm、0.6 mm不同芯径光纤、不同系列的大芯径光纤辐照损耗、辐致损耗恢复、发光光谱等实验研究。(3)应用蒙特卡罗方法研究了不同能量射线在不同芯径光纤中沉积能量分布、能量沉积深度分布、能量沉积角分布，建立了色心动力学方法研究辐照损耗机制，定性分析了损耗随光纤芯径的关系，给出了在约在10 Gy剂量的辐照下，光纤的光学密度随剂量增加出现拐点并逐步出现饱和。 (4)基于契伦辐射光激发理论和光纤束缚光传输理论，定量分析了激发光强与粒子束能量及粒子激发方向的关系。截止报告提交时，共发表与本课题研究内容相关论文5篇，SCI, EI检索2篇，申报国家发明专利2项。