Studies on Radiation Response of Optical Fibers

用14 MeV中子、热中子、Co γ射线辐照各种抗辐射光纤<60>。在辐照过程中原位测量光透射的诱导损失。利用光纤中色心密度与电荷陷阱能级的关系式，近似地解释了光纤的辐射响应。实验结果还表明，14 MeV中子辐照和γ-Co辐照的效应差别不大<60>。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，而不是由中子位移效应引起的结构变化。然而，掺硼光纤对热中子的响应不同于对其他辐射的响应。热中子与其它辐照方式的感生损失率也有很大差异。^<10>B（n，alpha）^7 Li反应影响的不是光纤的整个区域，而是特定区域的光传输。这种差异可以用光纤损伤机理的微观观察来解释。本研究报告没有讨论这一问题，但这是今后的一个重要课题。

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.