【作者】 罗文芸；

【导师】 王子华； 王廷云；

【作者基本信息】 上海大学 ， 电磁场与微波技术， 2013， 博士

【摘要】 光纤正被广泛应用于航天航空、军事、核医学和核工业等与辐射相关的领域，特别是辐射环境下的光纤通信更是越来越受到重视。石英光纤的抗辐射特性也一直是国际国内的研究热点。为了降低石英光纤的辐射敏感特性，研制具有抗辐射能力的石英光纤是非常必要的。本论文以高纯石英光纤材料作为研究对象，从射线与物质相互作用原理出发，分析辐射损伤导致的石英光纤材料中缺陷结构的形成机制，并建立“色心”动力学理论模型；同时，通过实验研究石英光纤材料辐射诱导产生的E色心的特性，以及预辐照与退火技术结合对其特性的影响。其具体研究内容如下：首先介绍了电子和γ射线与物质相互作用的原理，并讨论石英光纤材料辐射损伤机制，材料的微结构特征，以及石英光纤材料辐射诱导形成的几种基本点缺陷结构的原子结构特征。其次，研究了荷能粒子辐照石英光纤材料形成色心的机制，建立了色心动力学理论模型，即创造加激活的色心动力学模型，并讨论了色心形成的动力学过程，以及色心浓度与辐照剂量之间的变化关系。对于低能辐照粒子，色心主要由固有点缺陷形成；对于高能粒子辐照，色心的形成包括两个过程，即色心的创造过程和色心的激活过程。其中，色心的创造主要是由二氧化硅网格中疲劳键的断裂或网格中氧移位而形成，而色心的激活过程主要是由二氧化硅玻璃中固有点缺陷形成。然后，采用电子自旋共振（ESR）波谱仪和吸收光谱仪，对石英光纤材料的抗辐射特性进行了实验研究。实验结果表明，在室温条件下，γ射线辐照石英光纤材料产生的缺陷结构为典型的色心，并且色心可以通过退火处理得到有效的修复。同时，根据本论文建立的色心动力学模型，对色心浓度与辐照剂量的变化关系进行拟合，与实验结果基本一致，表明建立的模型有效。最后，通过实验，研究了预辐照并结合退火技术对石英光纤材料抗辐射特性的影响。研究结果表明，先用γ射线进行预辐照，然后进行热退火处理，可在再次辐照处理时，有效地降低石英光纤材料的辐射敏感特性，也就是再次辐射诱导产生的E色心浓度明显降低，使其抗辐照特性得到明显的增强；并且色心浓度与退火温度相关，当退火温度大于特定温度时，色心浓度才能迅速下降。本论文研究了辐射损伤导致石英光纤材料点缺陷结构产生的机理，探索通过预辐照，结合退火技术的方法，抑制石英光纤材料中点缺陷结构的形成，为提高石英光纤材料的抗辐射特性提供理论依据，同时也为制备具有抗辐射特性的石英光纤奠定了非常重要的理论和实验基础。更多还原

【Abstract】 Optical fiber is being widely used in aerospace, military, nuclear medicine,nuclear industry and other radiation related fields. And the optical fibercommunication in the radiation environment has received more and more attention.The anti-radiation properties of silica optical fiber have also been the internationaland domestic research focus. In order to reduce the radiation sensitivity, it isnecessary to develop the radiation-resistant silica optical fiber. In this dissertation,based on the principle of the interaction of radiation with matter, the formationmechanism of point defects induced by radiation damage in high-purity silica fibermaterial has been analyzed and a kinetic model for point defects has been established.Meanwhile, the characteristics of radiation-induced point defect E’ center in silicaoptical fiber material have been investigated, and influences of pre-irradiation andthermal annealing on E’ center have been studied by experiments. The main contentsare as follows:This paper firstly introduces the principle of electrons and γ-rays interact withmatter, discusses the microstructure characteristics of materials and the formationmechanism of point defects, and reviews the atomic structure of several basic pointdefects induced by radiation in silica optical fiber material.Secondly, the formation mechanism of E’ center induced by energetic particleirradiated in silica optical fiber material is analyzed in detail. According to thisformation mechanism of E’ center, a kinetic theory model has been established, thatis creation plus activation kinetic model. The formation dynamic process of E’centers is discussed. The relation of E’ center concentration changing with irradiationdose is obtained theoretically. For the low-energy particles, E’ centers are formedmainly by pre-existing defects. For high-energy particle, the production of E’ centerincludes two processes creation and activation. The cleavage of strained bonds or oxygen replacement in silica networks lead to the creation of new defects. Thepre-existing defects produce the activation.Then using electron spin resonance (ESR) spectroscopy and optical absorptionspectroscopy, the radiation characteristics of the silica optical fiber material havebeen investigated. The experimental results show that the point defect induced byγ-ray irradiation at room temperature in silica optical fiber material is typical E’center. And the E’ center can be effectively repaired by annealing treatment.According to the formation dynamic model of E’ center established in this paper, therelation of the concentration of E’ centers changing with irradiation dose weresimulated. The simulated results are in good agreement with the experimental results,which indicates that the model is effective.At last, the influences of pre-irradiation and thermal annealing on the radiationcharacteristic of the silica optical fiber material have been investigated by measuringESR spectra and optical absorptions. The results show if silica optical fiber materialhas been treated by pre-irradiation and subsequently thermal annealing, the radiationsensitivity can be reduced effectively when irradiated again. That is to say, theconcentration of E’ defect induced by irradiated again can be decreased effectively.The anti-radiation characteristics can be improved significantly. And the E’ defectconcentration is related with the annealing temperature. When the annealingtemperature is higher than a certain temperature, the concentration of E’ center candecrease rapidly.This paper has studied the formation mechanism of point defects induced byradiation damage in silica optical fiber material and explored through the method ofpre-irradiation and subsequent thermal annealing to decrease the generation of pointdefects. The results provide a theoretical basis not only for improving anti-radiationcharacteristics of the silica optical fiber material, but also for preparing theradiation-resistant silica optical fiber.更多还原