{gamma} and fission-reactor radiation effects on the visible-range transparency of aluminum-jacketed, all-silica optical fibers
- Optical Sciences Division, Naval Research Laboratory, Washington, DC 20375 (United States)
Four aluminum-jacketed, fluorine-doped silica clad optical fibers with silica core materials fabricated by differing technologies were subjected to sequential {sup 60}Co-{gamma} ray and fission-reactor irradiations (at {approximately}20 and 40{degree}C, respectively), an intervening isothermal anneal ({approximately}20{degree}C), and a final isochronal anneal (to 600{degree}C) while monitoring the radiation-induced absorption spectra in the range {approximately}400{endash}1000 nm. The two low-OH/low-chloride core fibers (one of which was doped with 0.5 mass{percent} fluorine) both developed bands at 660 and 760 nm which exceeded 10000 dB/km for doses in the range {approximately}10{sup 2}{endash}10{sup 6} Gy(Si); however, these bands declined to {lt}1000 dB/km by the end of the {gamma}-irradiation phase [12 MGy(Si) at 5.6 Gy(Si)/s]. All fibers displayed an {open_quote}{open_quote}UV band tail,{close_quote}{close_quote} which was the strongest in the high-chloride core fiber, as well as bands in the range {approximately}600{endash}630 nm generally attributed to nonbridging-oxygen hole centers (NBOHCs). During the {gamma}-irradiation phase the strengths of the NBOHC bands proved to be strongly dependent on the method of core material manufacture. Contrary to previous results for acrylate-jacketed fibers, no substantial bleaching of the UV-tail or NBOHC bands took place during {gamma} irradiation despite the continuous propagation of white light powers {approximately}5{endash}50 {mu}W. The incremental induced absorption spectra consequent to the reactor-irradiation [{approximately}4 MGy(Si) {gamma}-ray dose at 70 Gy(Si)/s, plus a fluence of {approx_gt}2.8-MeV neutrons {approximately}2{times}10{sup 16} cm{sup {minus}2}] were much less sensitive to fiber core material. The prospects for developing rad hard optical fibers for fusion reactor diagnostics are discussed in light of these findings.
- DOE Contract Number:
- AI02-93ER54214
- OSTI ID:
- 286538
- Journal Information:
- Journal of Applied Physics, Vol. 80, Issue 4; Other Information: PBD: Aug 1996
- Country of Publication:
- United States
- Language:
- English
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