scholarly journals Active Compensation of Radiation Effects on Optical Fibers for Sensing Applications

Sensors ◽  
2021 ◽  
Vol 21 (24) ◽  
pp. 8193
Author(s):  
Sohel Rana ◽  
Austin Fleming ◽  
Nirmala Kandadai ◽  
Harish Subbaraman
Keyword(s):  
Optical Fibers ◽  
Radiation Effects ◽  
Accurate Determination ◽  
Radiation Environment ◽  
Physical Parameters ◽  
Air Cavity ◽  
Sensing Applications ◽  
Fabry Perot ◽  
Radiation Induced

Neutron and gamma irradiation is known to compact silica, resulting in macroscopic changes in refractive index (RI) and geometric structure. The change in RI and linear compaction in a radiation environment is caused by three well-known mechanisms: (i) radiation-induced attenuation (RIA), (ii) radiation-induced compaction (RIC), and (iii) radiation-induced emission (RIE). These macroscopic changes induce errors in monitoring physical parameters such as temperature, pressure, and strain in optical fiber-based sensors, which limit their application in radiation environments. We present a cascaded Fabry–Perot interferometer (FPI) technique to measure macroscopic properties, such as radiation-induced change in RI and length compaction in real time to actively account for sensor drift. The proposed cascaded FPI consists of two cavities: the first cavity is an air cavity, and the second is a silica cavity. The length compaction from the air cavity is used to deduce the RI change within the silica cavity. We utilize fast Fourier transform (FFT) algorithm and two bandpass filters for the signal extraction of each cavity. Inclusion of such a simple cascaded FPI structure will enable accurate determination of physical parameters under the test.

scholarly journals Numerical Analysis of Radiation Effects on Fiber Optic Sensors

Sensors ◽  
2021 ◽  
Vol 21 (12) ◽  
pp. 4111
Author(s):  
Sohel Rana ◽  
Harish Subbaraman ◽  
Austin Fleming ◽  
Nirmala Kandadai
Keyword(s):  
Radiation Effects ◽  
Physical Parameters ◽  
Potential Candidate ◽  
Low Dose Radiation ◽  
Long Period Grating ◽  
Fiber Sensors ◽  
Fabry Perot ◽  
Radiation Induced ◽  
High Doses ◽  
Dose Radiation

Optical fiber sensors (OFS) are a potential candidate for monitoring physical parameters in nuclear environments. However, under an irradiation field the optical response of the OFS is modified via three primary mechanisms: (i) radiation-induced attenuation (RIA), (ii) radiation-induced emission (RIE), and (iii) radiation-induced compaction (RIC). For resonance-based sensors, RIC plays a significant role in modifying their performance characteristics. In this paper, we numerically investigate independently the effects of RIC and RIA on three types of OFS widely considered for radiation environments: fiber Bragg grating (FBG), long-period grating (LPG), and Fabry-Perot (F-P) sensors. In our RIC modeling, experimentally calculated refractive index (RI) changes due to low-dose radiation are extrapolated using a power law to calculate density changes at high doses. The changes in RI and length are subsequently calculated using the Lorentz–Lorenz relation and an established empirical equation, respectively. The effects of both the change in the RI and length contraction on OFS are modeled for both low and high doses using FIMMWAVE, a commercially available vectorial mode solver. An in-depth understanding of how radiation affects OFS may reveal various potential OFS applications in several types of radiation environments, such as nuclear reactors or in space.

scholarly journals Accurate determination of terahertz optical constants by vector network analyzer of Fabry–Perot response

2013 ◽  
Vol 38 (24) ◽  
pp. 5438 ◽  
Author(s):  
Wenfeng Sun ◽  
Bin Yang ◽  
Xinke Wang ◽  
Yan Zhang ◽  
Robert Donnan
Keyword(s):  
Optical Constants ◽  
Accurate Determination ◽  
Vector Network Analyzer ◽  
Network Analyzer ◽  
Fabry Perot

Accurate determination of the thermal variation of the aperture of step-index optical fibers

1988 ◽  
Vol 27 (23) ◽  
pp. 4822 ◽  
Author(s):  
J. Dugas ◽  
M. Sotom ◽  
E. Douhe ◽  
L. Martin ◽  
P. Destruel
Keyword(s):  
Optical Fibers ◽  
Accurate Determination ◽  
Thermal Variation ◽  
Step Index

Radiation-Induced-Defects Localization in Single-Mode Optical Fibers

2005 ◽  
Vol 480-481 ◽  
pp. 329-332 ◽  
Author(s):  
Sylvain Girard ◽  
A. Boukenter ◽  
Y. Ouerdane ◽  
J.-P. Meunier
Keyword(s):  
Optical Fibers ◽  
Single Mode ◽  
Wavelength Dependence ◽  
Radiation Sensitivity ◽  
Color Centers ◽  
Strong Interactions ◽  
Radiation Induced ◽  
Different Color ◽  
Induced Defects

We studied the defects at the origins of the permanent radiation-induced attenuation in four g-rays irradiated single-mode germanosilicate optical fibers (~1 MeV; 1.2 kGy; 0.3 Gy/s) in the spectral range 400 - 1700 nm. We determined the wavelength dependence of the following cladding codopant influences: germanium (0.3 %), phosphorus (0.3 %), fluorine (0.3 %) on the germanosilicate (13 %) fiber radiation responses. We identified some of the different color centers produced by g-rays and we evaluated their localization in the fiber cross-section through the determination of the radial distribution of the radiation-induced absorption at 633 nm. We also evidenced the strong interactions between these three codopants. In particular, our results showed that the properties of the phosphorus-related color centers, which mainly determine the fiber infrared radiation sensitivity, are strongly influenced by the germanium- and fluorine-codoping.

scholarly journals Ground-Based and Space Observations of Interacting Binaries

2011 ◽  
Vol 7 (S282) ◽  
pp. 21-26
Author(s):  
Panagiotis G. Niarchos
Keyword(s):  
Binary Systems ◽  
Accurate Determination ◽  
Space Missions ◽  
Light Curves ◽  
Physical Parameters ◽  
Multi Wavelength ◽  
Low Mass ◽  
Space Observations

AbstractMulti-wavelength observational data, obtained from ground-based and space observations are used to compute the physical parameters of the observed Interacting Binaries (IBs) and study the interactions and physical processes in these systems. In addition, the database of IBs from ground-based surveys and space missions will provide light curves for many thousands of new binary systems for which extensive follow up ground-based observations can be carried out. In certain cases, light curves of superior quality will allow studies of fine effects of stellar activity and very accurate determination of stellar parameters. Moreover, many new discoveries of interesting systems are expected from ground-based all-sky surveys and space missions, including low mass binaries and star-planet binary systems. The most important current and future programs of observations of IBs from ground and space are presented.

A setup for synchrotron-radiation-induced total reflection X-ray fluorescence and X-ray absorption near-edge structure recently commissioned at BESSY II BAMline

2016 ◽  
Vol 23 (3) ◽  
pp. 820-824 ◽  
Author(s):  
U. Fittschen ◽  
A. Guilherme ◽  
S. Böttger ◽  
D. Rosenberg ◽  
M. Menzel ◽  
...  
Keyword(s):  
Accurate Determination ◽  
Total Reflection ◽  
Edge Structure ◽  
X Ray ◽  
Unknown Species ◽  
Radiation Induced ◽  
Set Up ◽  
Reflecting Surface ◽  
X Ray Absorption

An automatic sample changer chamber for total reflection X-ray fluorescence (TXRF) and X-ray absorption near-edge structure (XANES) analysis in TXRF geometry was successfully set up at the BAMline at BESSY II. TXRF and TXRF-XANES are valuable tools for elemental determination and speciation, especially where sample amounts are limited (<1 mg) and concentrations are low (ng ml−1to µg ml−1). TXRF requires a well defined geometry regarding the reflecting surface of a sample carrier and the synchrotron beam. The newly installed chamber allows for reliable sample positioning, remote sample changing and evacuation of the fluorescence beam path. The chamber was successfully used showing accurate determination of elemental amounts in the certified reference material NIST water 1640. Low limits of detection of less than 100 fg absolute (10 pg ml−1) for Ni were found. TXRF-XANES on different Re species was applied. An unknown species of Re was found to be Re in the +7 oxidation state.

scholarly journals Report of High Temperature Measurements with a Fabry-Perot Extensometer

2020 ◽  
Vol 225 ◽  
pp. 01011
Author(s):  
G. Cheymol ◽  
A. Verneuil ◽  
P. Grange ◽  
H. Maskrot ◽  
C. Destouches
Keyword(s):  
High Temperature ◽  
Reactor Core ◽  
Young Modulus ◽  
Neutron Radiation ◽  
Physical Parameters ◽  
Useful Signal ◽  
Compact Size ◽  
Fabry Perot ◽  
Radiation Induced ◽  
The Impact

Fabry-Perot (FP) sensors like other Fiber Optic (FO) sensors may be of particular interest for in pile experiments in MTR with little room available thanks to their compact size. Light weight also reduces gamma heating hence limiting the thermal effect. Different physical parameters such as temperature, strain, displacement, vibration, pressure, or refractive index may be sensed through the measurement of the optical path length difference in the cavity. We have developed a Fabry-Perot extensometer able to operate at high temperature (up to 400°C), under a high level of radiation (neutron and gamma flux). The measurement based on interferometry is largely insensitive to radiation induced attenuation (RIA) thanks to the wavelength encoding of the useful signal, but for such high fluence as encountered in a reactor core, a special rad-hard fiber is needed. Operating in the wavelength domain around 1ím remains preferable to minimize the impact of irradiation. Moreover, fast neutron radiation is expected to change the structure of the fiber and possibly others materials in the transducer. Then, we revised the basic scheme of Extrinsic Fabry-Perot Interferometer (EFPI) so that the effects of compaction remain limited. Tests under mixed neutron and gamma irradiation permitted to verify the general behavior and particularly the low drift with radiation induced compaction (RIC). Also, two types of tests have been conducted to verify the accuracy at high temperature. The first ones are “measurements” of thermal dilatation of materials: the sensor is fixed on a sample and knowing its thermal expansion, it is possible to predict the measurement expected from the optical sensor when the temperature is increased from low to high temperature. The comparison between the predicted and experimental outputs informs on how the sensor is accurate. The second types are tests on a tensile test bench operating at high temperature. The Fabry-Perot measurements are compared, in the elastic domain, with the expected strain given by the Young modulus of the material, and also on a larger strain domain, with the measurements of a high temperature axial extensometer. Both types of tests are presented and commented.

scholarly journals Non-Metamict Aeschynite-(Y), Polycrase-(Y), and Samarskite-(Y) in NYF Pegmatites from Arvogno, Vigezzo Valley (Central Alps, Italy)

Minerals ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 313
Author(s):  
Alessandro Guastoni ◽  
Luciano Secco ◽  
Radek Škoda ◽  
Fabrizio Nestola ◽  
Mariangela Schiazza ◽  
...  
Keyword(s):  
Structural Damage ◽  
Accurate Determination ◽  
Chemical Compositions ◽  
Central Alps ◽  
X Ray Diffraction ◽  
Space Groups ◽  
Cell Parameters ◽  
Radiation Induced ◽  
Cell Data

At Arvogno, Vigezzo valley in the Central Alps, Italy, pegmatite dikes are unique in the scenario of a tertiary alpine pegmatite field because they show marked geochemical and mineralogical niobium–yttrium–fluorine features. These pegmatites contain AB2O6 aeschynite group minerals and ABX2O8 euxenite group minerals as typical accessory minerals including aeschynite-(Y), polycrase-(Y), and samarskite-(Y). They are associated with additional typical minerals such as fluorite, Y-dominant silicates, and xenotime-(Y). The Y–Nb–Ti–Ta AB2O6 and ABX2O8 oxides at the Arvogno pegmatites did not exhibit any textural and compositional features of oxidation or weathering. They are characterized by low self-radiation-induced structural damage, leading to the acquisition of unit-cell data for aeschynite-(Y), polycrase-(Y), and samarskite-(Y) by single-crystal X-ray diffraction. Aeschynite-(Y) and polycrase-(Y) crystals allowed for both to provide space groups whereas samarskite-(Y) was the first crystal from pegmatites for which cell-data were obtained at room temperature but did not allow for the accurate determination of the space group. According to the chemical compositions defined by Ti-dominant content at the B-site, the cell parameters, respectively, corresponded to polycrase-(Y), aeschynite-(Y), and the monoclinic cell of samarskite-(Y). Emplacement of Alpine pegmatites can be related to the progressive regional metamorphic rejuvenation from east to west in the Central Alps, considering the progressive cooling of the thermal Lepontine Barrovian metamorphic dome. Previous studies considered magmatic pulses that led to emplace the pegmatite field in the Central Alps. As an example, the pegmatites that intruded the Bergell massif were aged at 28–25 millions of years or younger, around 20–22 m.y.

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