Studies on Radiation Response of Optical Fibers

用14 MeV中子、热中子、60&Coγ射线对各种耐辐射光纤进行了辐照。在辐照过程中，原位测量了光传输的诱导损失。用与光纤中电荷陷阱能级相关的色心密度方程近似解释了光纤的辐射响应。实验结果还表明，14 MeV中子和^&lt；60；Co伽马射线辐照的效应没有太大差别。这意味着光纤的辐射响应主要受与剂量密切相关的电离效应的影响，而不是受中子位移效应引起的结构变化的影响。然而，掺硼光纤对热中子的响应与对其他辐射的响应不同。热中子与其他辐照的诱发损失率也有很大差异。^lt；10&>B(n，α)^7Li反应影响的不是整个光纤区域的光传输，而是特定区域的光传输。这种差异可以通过对光纤损伤机制的微观检查来解释。目前的研究没有讨论这一问题，但这是未来的一个重要课题。

Various radiation-resistant optical fibers were irradiated with 14-MeV neutrons, thermal neutrons ^<60>Co gamma-rays. The induced loss in light transmission was measured in-situ during irradiation. The radiation response of optical fibers was approximately explained by using an equation for the density of color centers related to charge trap levels in optical fibers under irradiation. Also experimental results showed there was not large difference in effects between 14-MeV neutron and ^<60>Co gamma-ray irradiations. This means that radiation response of optical fibers is influenced predominately by ionization effects closely related with dose, rather than by structural changes due to neutron displacement effects. However, response of B-doped optical fibers to thermal neutrons was different from that to other radiations. There was also large difference in the induced loss rate between thermal neutron and other irradiations. The ^<10>B (n, alpha) ^7Li reaction affects light transmission in not whole but specialized region of the optical fibers. The difference may be explained by the microscopic examination of the damage mechanism of optical fibers. This is not discussed in the present study but is an important subject in the future.