基于偏振正交双频DBR激光器的腐蚀声发射传感器研究

The corrosion detecting technology based on acoustic emission is emerging recently in NDT (nondestructive testing), especially promising in online monitoring of industrial field corrosion such as the nuclear power's key material area. However, the currently used traditional acoustic emission sensor is of low sensitivity and not liable to conduct contributed online monitoring. The project aims at to launch online monitoring for metal corrosion by means of acoustic emission. A corrosion acoustic emission sensor is proposed on foundation of the orthogonally polarized DBR fiber laser. It can not only fulfill the requirements of metal corrosion monitoring, but also achieve distributed network as well as high-fidelity transmission of the detected signals over long distance. We first investigate the DBR laser's working mechanism and theoretical model, and reveal how the resonant cavity's parameters affect the property of the corrosion's acoustic emission sensor. On the former basis, an optimization design is established, meanwhile the multiple DBR sensors' networking and array signal processing methods are demonstrated. In the end, performance test and calibration experiment on the sensor are carried out. The research will provide theoretical and technical basis for both the orthogonally polarized DBR corrosion acoustic emission sensor and optimization design and fabrication for networking. It shows great significance in online corrosion monitoring of metal corrosion, particularly the nuclear-level key material.

声发射腐蚀检测技术是近些年来逐渐兴起的一种无损检测技术，在核电关键材料等工业现场腐蚀在线监测领域具有很好的应用前景。但是目前传统声发射传感器灵敏度较低、不易分布式在线监测。本项目以金属腐蚀的声发射在线监测为目标，提出一种基于偏振正交DBR光纤激光器的腐蚀声发射传感器，不仅能够满足金属腐蚀在线监测对传感器灵敏度的要求，还能实现信号的长距离高保真传输与分布式组网。本项目通过对DBR激光器的工作机理及模型进行研究，找到DBR腐蚀声发射传感器的谐振腔参数对其性能影响的规律，并在此基础上进行传感器的优化设计；研究多DBR传感器组网及阵列信号处理的方法；最终对传感器进行性能测试与标定实验。本项目的研究将为偏振正交DBR腐蚀声发射传感器及组网的优化设计与制作提供理论和技术基础，对金属腐蚀特别是核级关键材料的在线腐蚀监测具有重要意义。

本课题以核电关键材料的工业现场腐蚀在线监测为应用背景，利用DBR正交双频光纤激光器作为腐蚀声发射传感器，对关键材料的腐蚀进行在线监测。依托DBR正交双频光纤激光传感器，构建了DBR用于腐蚀声发射传感时的声场耦合模型；利用准分子激光器在线刻写布拉格光纤光栅(FBG)，制作了DBR正交双频光纤激光器。对制得的DBR正交双频激光器的应力和振动响应进行了测试与分析，对声传感性能进行了理论分析与实验测试。实验室搭建了以304不锈钢薄板为腐蚀监测对象的腐蚀声发射DBR传感实验系统，并用制得的DBR腐蚀声发射传感器对304不锈钢薄板在酸性三氯化铁溶液中的腐蚀情况进行了在线监测。由于DBR光纤传感器自身抗电磁干扰，抗化学腐蚀，易于铺设与复用，易于信号长距离传输等优点，DBR腐蚀声发射传感器的研究可为核电关键材料的在线腐蚀监测提供更加低成本，高效率的解决方案。研究内容将为DBR腐蚀声发射传感器实际用于腐蚀在线监测提供有力的理论基础和前期实验研究基础。