Influence of neutron and gamma-ray irradiations on rad-hard optical fiber

Abstract

We investigated point defects induced in rad-hard Fluorine-doped optical fibers using both a mixed source of neutrons (fluences from 1015 to 1017 n/cm2) and γ-rays (doses from 0.02 to 2 MGy) and by a γ-ray source (dose up to 10 MGy). By combining several complementary spectroscopic techniques such as radiation-induced attenuation, confocal micro-luminescence, time-resolved photo-luminescence and electron paramagnetic resonance, we evidenced intrinsic and hydrogen-related defects. The comparison between the two irradiation sources highlights\ud close similarities among the spectroscopic properties of the induced defects and the linear correlation of their concentration up to 1016 n/cm2. These results are interpreted on the basis of the generation processes of defects from precursors sites, that are common to both γ-rays and neutrons. In contrast, the highest neutron fluence (1017 n/cm2) causes peculiar effects, such as the growth of a photoluminescence and variations of the spectral and decay properties of the emission related with nonbridging oxygen hole centers, that are likely due to silica network modification

Bragg wavelength shift for irradiated polymer fiber Bragg grating

“…Although many authors were uncertain of the effect of low fluence neutrons on the optical properties of fibers, Brichard et al [20] observed the change of the refractive index in neutron amorphous irradiated silica and the corresponding compaction effect. Whereas, Morana et al, [21] noticed the same behavior for optical parameters when studied the effect of mixed γ-rays and neutrons of fluence 10 17 n/cm 2 .…”

“…Several literatures reported the effect of a mixed neutrongamma irradiation on silica optical fibers [20,21]. Brichard et al [20] reported the effect on fluorine-doped silica clad optical fibers with pure silica core material.…”

Features of the Fiber Optics Application in Iter

“…Наконец, рассмотрим тесты по облучению ле-гированных фтором кварцевых волокон в акрило-вой оболочке диаметром 0,125 мм [12]. Исследова-ния были проведены на ядерном реакторе (при нейтронных флюенсах от 10 15 до 10 17 н/см 2 и со-путствующих гамма-дозах от 0,02 до 2 МГр) и на гамма-источнике (при дозах до 10 МГр).…”

“…Тем не менее гарантировать необходимое для примене-ния на ИТЭР долгосрочное, более 15 лет, сохранение водорода в таком волокне не представляется воз-можным, а значит, и применить его на практике нельзя. Наиболее подходящим является оптоволокно из плавленого кварца, легированного фтором [12]. Отметим, что для того чтобы убедиться в качестве ис-ходного волокна, необходимо до изготовления оптических жгутов облучить образец, например, в гамма-источнике и проанализировать результат, сравнив его с результатами облучения радиационно-стойких образцов.…”

Radiation hardening of silica glass through fictive temperature reduction

“…The use of silica glass optical fibers in radiative environments is of major interest to the civil, military, or space fields, due to the numerous advantages of the fibers and in particular their electromagnetic immunity, wide bandwidth, light weight, and low volume . These optical fibers can be used as tools for transmitting information, as sensors, or as diagnostic elements.…”