41 results on '"Berghmans, F."'
Search Results
2. Toward the Development of Radiation-Tolerant Instrumentation Data Links for Thermonuclear Fusion Experiments.
- Author
-
Fernandez, Alberto Fernandez, Berghmans, F., Brichard, B., and Decreton, M.
- Subjects
- *
RADIATION tolerance , *CONTROLLED fusion , *OPTOELECTRONIC devices - Abstract
Presents a study that assessed the development of radiation-tolerant instrumentation data links that could be used in thermonuclear fusion experiments. Background on the digital optoelectronic serial data link for International Thermonuclear Experimental Reactor remote handling tasks; Discussion on radiation-hardened electronics; Analysis of the implementation of error-correction schemes.
- Published
- 2002
- Full Text
- View/download PDF
3. Design and Characterization of a Radiation-Tolerant Optical Transmitter Using Discrete COTS Bipolar Transistors and VCSELs.
- Author
-
Berghmans, F., Embrechts, K., Van Uffelen, M., Coenen, S., Decreton, M., and Van Gorp, J.
- Subjects
- *
LASERS , *OPTOELECTRONICS - Abstract
Focuses on a study that tested a radiation-tolerant opto-electronic transmitter based on vertical-cavity surface-emitting lasers and dedicated driver electronics consisting of discrete components. Background and method; Irradiation results and discussion; Conclusion.
- Published
- 2002
- Full Text
- View/download PDF
4. Radiation-Resistant WDM Optical Link for Thermonuclear Fusion Reactor Instrumentation.
- Author
-
Fernandez, A. Fernandez, Berghmans, F., Brichard, B., Borgermans, P., Gusarov, A. I., Van Uffelen, M., Megret, P., Decreton, M., Blondel, M., and Delchambre, A.
- Subjects
- *
WAVELENGTH division multiplexing , *FUSION reactors , *DETECTORS - Abstract
Focuses on a study which examined the wavelength division multiplexing (WDM) optical link for the thermonuclear fusion reactor instrumentation. Information on the force sensor based on multiplexed Fiber Bragg grating strain sensors; Details on WDM coupler behavior under radiation; Conclusion.
- Published
- 2001
- Full Text
- View/download PDF
5. Behavior of Fibre Bragg Gratings Under High Total Dose Gamma Radiation.
- Author
-
Gusarov, A. I. and Berghmans, F.
- Subjects
- *
OPTICAL fiber detectors , *IRRADIATION - Abstract
Presents information on a study which examined the effect of MGy dose level gamma-irradiation on the parameters of fibre Bragg gratings (FBG) intended for sensing applications. Properties of optical fibre sensors and FBG; Experimental details; Results and discussion; Conclusions.
- Published
- 2000
- Full Text
- View/download PDF
6. Induced optical absorption of silicate glasses due to gamma irradiation at high temperatures
- Author
-
Gusarov, A., Huysmans, S., Berghmans, F., Glebova, L., Glebov, L., and Hodgson, E.R.
- Subjects
- *
ABSORPTION , *SILICATES , *GAMMA rays , *HIGH temperatures , *ANNEALING of crystals , *ULTRAVIOLET radiation , *NUCLEAR reactors - Abstract
Abstract: Gamma radiation-induced optical absorption in 75SiO2–22Na2O–3CaO (wt.%) multi-component glass and in the same glass additionally doped with 0.05wt.% CeO2 has been studied, with irradiations performed at 70, 200, and 350°C, 25kGy/h up to a dose of 0.6MGy. For the undoped glass irradiation at 70°C produces strong optical absorption from 700nm down to the UV. Irradiation at 200°C gives a lower level of optical absorption with a similar band composition. No induced optical absorption has been detected after irradiation at 350°C. Annealing at 200°C for 24h completely suppresses the induced optical absorption. Introduction of cerium increases the level of induced absorption in the UV range for irradiation at 70°C, and also creates bands stable up to 350°C. The results show that silica and sapphire, which are considered as main candidate materials for ITER diagnostic windows and other optical components, can potentially be complemented with multi-component silicate glasses. These materials may allow one to control the radioluminescence, and in addition provide a range of refractive indices required for achromatic lenses. [Copyright &y& Elsevier]
- Published
- 2010
- Full Text
- View/download PDF
7. Design and Assessment of a High Gamma-Dose Tolerant VCSEL Driver With Discrete SiGe HBTs.
- Author
-
Leroux, P., Van Uffelen, M., Berghmans, F., and Giraud, A.
- Subjects
- *
GAMMA rays , *BIPOLAR transistors , *DIGITAL communications , *FUSION reactors , *OPTICAL fibers , *SOLID-state lasers , *BREAKDOWN voltage , *INTEGRATED circuits , *NUCLEAR science - Abstract
A digital VCSEL driver has been designed, simulated and assessed under radiation, using discrete SiGe HBTs. The circuit tolerates high levels of gamma radiation, up to 12 MGy, features less than 2% drift in the forward current of the VCSEL and operates well above 10 MHz. The output duty cycle shows no notable degradation at 200 kHz, enabling the design of robust analog and digital communication systems using pulse-width-modulation (PWM) schemes. [ABSTRACT FROM AUTHOR]
- Published
- 2006
- Full Text
- View/download PDF
8. Chemical Composition Fiber Gratings in a High Mixed Gamma Neutron Radiation Field.
- Author
-
Fernandez, A. Fernandez, Brichard, B., Berghmans, F., El Rabii, H., Fokine, M., and Popov, M.
- Subjects
- *
REFRACTIVE index , *ULTRAVIOLET radiation , *THERMAL neutrons , *ATMOSPHERIC radio refractivity , *OPTICAL fibers , *NUCLEAR energy , *DATA transmission systems , *FIBER optics , *DETECTORS - Abstract
Fiber Bragg gratings are all-fiber wavelength-selective refractive index structures manufactured through UV exposure of optical fibers. Their applications range from WDM all-fiber filters, dispersion compensators and fiber laser resonators for optical telecommunication applications to different types of point or distributed optical fiber sensors for a large variety of applications. The nuclear industry is considering the use of photonic technology for data communication in the next generation of nuclear power plants. In addition, fiber Bragg grating sensors are being evaluated by the nuclear industry for structural integrity and temperature monitoring. This work aims to study, in harsh radiation environments, a new type of FBG referred to as chemical composition grating. These gratings differ from other types of FBG in that their refractive index structure is attributed to a change in the chemical composition. Chemical composition gratings have shown to be extremely temperature stable surviving temperatures in excess of 1000 °C. We have experimentally studied the effect of very harsh gamma- neutron radiation on the properties of chemical composition gratings fabricated in a Ge-F doped silica optical fiber. [ABSTRACT FROM AUTHOR]
- Published
- 2006
- Full Text
- View/download PDF
9. Dose-Rate Dependencies in Gamma-Irradiated Fiber Bragg Grating Filters.
- Author
-
Fernandez, Alberto Fernandez, Brichard, B., Berghmans, F., and Decreton, M.
- Subjects
- *
FILTERS & filtration , *IRRADIATION , *FIBER optics , *NUCLEAR power plants - Abstract
Presents a study that investigated dose-rate effects on gamma-irradiated fiber Bragg grating filters. Examination on the application problem concerning electronic or photonic equipment in nuclear environments; Analysis of fiber Bragg gratings under pure gamma radiation; Assessment on the use of fiber-optic technology for data communication in nuclear power plants.
- Published
- 2002
- Full Text
- View/download PDF
10. Origin of the Radiation-Induced OH Vibration Band in Polymer-Coated Optical Fibers Irradiated in a Nuclear Fission Reactor.
- Author
-
Brichard, B., Fernandez, A. Fernandez, Berghmans, F., and Decreton, M.
- Subjects
- *
SILICA , *IONIZING radiation , *DIFFUSION , *HYDROGEN - Abstract
Presents a study that investigated the radiation-induced absorption of pure silica core fibers exposed to fission nuclear radiation. Background on the effect of ionizing radiation on the optical properties of silicon dioxide glasses; Analysis of an estimate of the recoil proton contribution; Examination of hydrogen diffusion.
- Published
- 2002
- Full Text
- View/download PDF
11. Radiation-Induced Effects on Fiber Bragg Gratings Inscribed in Highly Birefringent Photonic Crystal Fiber.
- Author
-
Morana, A., Baghdasaryan, T., Girard, S., Marin, E., Geernaert, T., Thienpont, H., Berghmans, F., Boukenter, A., and Ouerdane, Y.
- Subjects
- *
FIBER Bragg gratings , *RADIATION damage , *PHOTONIC crystal fibers , *BIREFRINGENCE , *MICROSTRUCTURE - Abstract
The fiber Bragg gratings (FBGs) inside photonic crystal fibers (PCFs) having high fiber birefringence, such as in PCF with butterfly shape microstructure, are characterized by two Bragg peaks. The spectral distance between these two peaks is not affected by a change of temperature or by a longitudinally applied strain, but this spectral separation evolves when the sensor is subjected to a transversal strain. This makes such FBGs inscribed in highly birefringent PCFs very interesting for structural health monitoring of civil structures, as well as for operation in harsh environments such as the ones associated with the nuclear industry. In this paper, we monitor the radiation-induced Bragg wavelength shift (RI-BWS) of the punctual sensor and the radiation-induced attenuation in the fiber used for its inscription up to a dose of 1.5 MGy(SiO2). Even if we observe a RI-BWS for both Bragg peaks, the spectral distance between them only slightly evolves, of less than 10 pm. These gratings are then very promising sensors for the structural health monitoring of nuclear facilities. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
12. Characterization of scintillating materials in use for brachytherapy fiber based dosimeters.
- Author
-
Cometti, S., Gierej, A., Giaz, A., Lomazzi, S., Baghdasaryan, T., Van Erps, J., Berghmans, F., Santoro, R., Caccia, M., and O'Keeffe, S.
- Subjects
- *
SCINTILLATORS , *OPTICAL measurements , *DOSIMETERS , *RADIOISOTOPE brachytherapy , *LIGHT absorption , *FIBERS - Abstract
This paper reports the characterization of two scintillating materials in powder form, Gadox and YVO embedded in a light-activated resin, used in a probe developed for oncological brachytherapy in-vivo dosimetry. The materials were characterized in terms of internal absorption, scintillation decay time, and light yield. The measurement of the optical characteristics highlighted a significant internal absorption at the scintillation light wavelength, with values of 6.5 dB/mm for Gadox and 14.1 dB/mm for YVO. Measurements of the characteristics scintillation time and of the light yield were performed with a novel method based on single photon counting, profiting from the long decay time of the materials under study. Measurements have been complemented by a two-step simulation with Geant4 to study the energy deposition followed by a ZEMAX OpticStudio® ray tracing to estimate the light collection efficiency. The decay time for scintillating materials were measured to be τ G a d o x = (458 ± 3 ± 3) μ s and τ Y V O = (451 ± 8 ± 3) μ s and the estimated values of the light yield are (7.1 ± 0.5) × 104 photon/MeV for Gadox and (4.8 ± 0.5) × 104 photon/MeV for YVO. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
13. Temperature monitoring using fibre optic sensors in a lead-bismuth eutectic cooled nuclear fuel assembly.
- Author
-
De Pauw, B., Lamberti, A., Ertveldt, J., Rezayat, A., Vanlanduit, S., Van Tichelen, K., and Berghmans, F.
- Subjects
- *
FIBER optical sensors , *TEMPERATURE measurements , *LEAD-bismuth alloys , *EUTECTIC alloys , *NUCLEAR fuels , *COOLING , *NUCLEAR reactors - Abstract
In-core temperature measurements are crucial to assess the condition of nuclear reactor components. The sensors that measure temperature must respond adequately in order, for example, to actuate safety systems that will mitigate the consequences of an undesired temperature excursion and to prevent component failure. This issue is exacerbated in new reactor designs that use liquid metals, such as for example a molten lead-bismuth eutectic, as coolant. Unlike water cooled reactors that need to operate at high pressure to raise the boiling point of water, liquid metal cooled reactors can operate at high temperatures whilst keeping the pressure at lower levels. In this paper we demonstrate the use of optical fibre sensors to measure the temperature distribution in a lead-bismuth eutectic cooled installation and we derive functional input e.g. the temperature control system or other systems that rely on accurate temperature actuation. This first-of-a-kind experiment demonstrates the potential of optical fibre based instrumentation in these environments. We focus on measuring the surface temperature of the individual fuel rods in the fuel assembly, but the technique can also be applied to other components or sections of the installation. We show that these surface temperatures can be experimentally measured with limited intervention on the fuel pin owing to the small geometry and fundamental properties of the optical fibres. The unique properties of the fibre sensors allowed acquiring the surface temperatures with a resolution of 30 mK. With these sensors, we assess the condition of the test section containing the fuel assembly during different steps of the operation of the facility, including the heating and verification of the vacuum of the loop as well as the filling and draining of the LBE loop. We also identify a simulated electrical shut-down and heating circuit failure in the primed installation. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
14. Operational modal analysis of flow-induced vibration of nuclear fuel rods in a turbulent axial flow.
- Author
-
De Pauw, B., Weijtjens, W., Vanlanduit, S., Van Tichelen, K., and Berghmans, F.
- Subjects
- *
VIBRATION (Mechanics) , *NUCLEAR fuel rods , *TURBULENCE , *AXIAL flow , *ELASTICITY - Abstract
Flow-induced vibration of nuclear reactor fuel pins can result in mechanical noise and lead to failure of the reactor's fuel assembly. This problem can be exacerbated in the new generation of liquid heavy metal fast reactors that use a much denser and more viscous coolant in the reactor core. An investigation of the flow-induced vibration in these particular conditions is therefore essential. In this paper, we describe an analysis technique to evaluate flow-induced vibration of nuclear reactor fuel pins subjected to a turbulent axial flow of heavy metal. We deal with a single fuel pin mockup designed for the lead–bismuth eutectic (LBE) cooled MYRRHA reactor which is subjected to similar flow conditions as in the reactor core. Our analysis is based on operational modal analysis (OMA) techniques. We show that the accuracy and precision of our OMA technique is higher compared to traditional methods and that it allows evaluating the evolution of modal parameters in operational conditions. We also demonstrate the possible onset of a fluid-elastic instability by tracking the modal parameters with increasing flow velocity. [ABSTRACT FROM AUTHOR]
- Published
- 2015
- Full Text
- View/download PDF
15. Gamma-irradiation tests of IR optical fibres for ITER thermography—a case study.
- Author
-
Reichle, R., Brichard, B., Pocheau, C., Jouve, M., van Ierschot, S., Martinez, S., Ooms, H., Berghmans, F., and Decréton, M.
- Subjects
- *
GAMMA rays , *OPTICAL fibers , *THERMOGRAPHY , *IRRADIATION , *SILICA - Abstract
In the course of the development of a concept for a spectrally resolving infrared thermography diagnostic for the ITER divertor we have tested 3 types of infrared (IR) fibres in Co60 irradiation facilities under γ irradiation. The fibres were ZrF4 (and HfF4) fibres from different manufacturers, hollow fibres (silica capillaries with internal Ag/AgJ coating) and a sapphire fibre. For the IR range, only the latter fibre type encourages to go further for neutron tests in a reactor. If one restricted the interest onto the near infrared range, high purity core silica fibres could be used. This study might be seen as a typical example of the relation between diagnostic development for a nuclear environment and irradiation experiments. [ABSTRACT FROM AUTHOR]
- Published
- 2008
- Full Text
- View/download PDF
16. Benchmarking of deformation and vibration measurement techniques for nuclear fuel pins.
- Author
-
De Pauw, B., Vanlanduit, S., Van Tichelen, K., Geernaert, T., Chah, K., and Berghmans, F.
- Subjects
- *
DEFORMATIONS (Mechanics) , *VIBRATION measurements , *BENCHMARKING (Management) , *NUCLEAR fuels , *FUEL pins , *ACCELEROMETERS - Abstract
Highlights: [•] We evaluate six different vibration sensing techniques. [•] We compare the SNR and R 2 of the response signal of the sensors. [•] The amplitudes were up to 60m at a frequency of 8.5Hz. [•] The optical techniques and the MEMS-type accelerometer prove superior. [•] Considering the constraints, we believe that the FBG are our best option. [ABSTRACT FROM AUTHOR]
- Published
- 2013
- Full Text
- View/download PDF
17. Highly birefringent soft glass rectangular photonic crystal fibers with elliptical holes.
- Author
-
Buczynski, R., Kujawa, I., Pysz, D., Martynkien, T., Berghmans, F., Thienpont, H., and Stepien, R.
- Subjects
- *
PHOTONICS , *CRYSTAL whiskers , *DOUBLE refraction , *VOIGT effect , *LATTICE theory - Abstract
In this paper we report on the fabrication of highly birefringent photonic crystal fiber with a photonic cladding composed of elliptical holes ordered in a rectangular lattice. The fiber features a group birefringence G of 0.82×10−4 at 725 nm. We discuss the influence of structural parameters including the ellipticity of the air holes and the aspect ratio of the rectangular lattice on the birefringence and on the modal properties of the fiber. [ABSTRACT FROM AUTHOR]
- Published
- 2010
- Full Text
- View/download PDF
18. Transverse UV-laser irradiation-induced defects and absorption in a single-mode erbium-doped optical fiber
- Author
-
Tortech, B., Ouerdane, Y., Boukenter, A., Meunier, J.-P., Girard, S., Van Uffelen, M., Régnier, E., Berghmans, F., and Thienpont, H.
- Subjects
- *
ULTRAVIOLET radiation , *SHEAR waves , *ERBIUM , *OPTICAL fibers , *RADIATION injuries , *ABSORPTION , *PHOTOLUMINESCENCE - Abstract
Abstract: Near UV-visible absorption coefficients of an erbium-doped optical fiber were investigated through an original technique based on a transverse cw UV-laser irradiation operating at 244nm. Such irradiation leads to the generation of a quite intense guided luminescence signal in near UV spectral range. This photoluminescence probe source combined with a longitudinal translation of the fiber sample (at a constant velocity) along the UV-laser irradiation, presents several major advantages: (i) we bypass and avoid the procedures classically used to study the radiation induced attenuation which are not adapted to our case mainly because the samples present a very strong absorption with significant difficulties due to the injection of adequate UV-light levels in a small fiber diameter; (ii) the influence of the laser irradiation on the host matrix of the optical fiber is directly correlated to the evolution of the generated photoluminescence signal and (iii) in our experimental conditions, short fiber sample lengths (typically 20–30cm) suffice to determine the associated absorption coefficients over the entire studied spectral domain. The generated photoluminescence signal is also used to characterize the absorption of the erbium ions in the same wavelength range with no cut-back method needed. [Copyright &y& Elsevier]
- Published
- 2009
- Full Text
- View/download PDF
19. Birefringent photonic crystal fibers with zero polarimetric sensitivity to temperature.
- Author
-
Martynkien, T., Anuszkiewicz, A., Statkiewicz-Barabach, G., Olszewski, J., Golojuch, G., Szczurowski, M., Urbanczyk, W., Wojcik, J., Mergo, P., Makara, M., Nasilowski, T., Berghmans, F., and Thienpont, H.
- Subjects
- *
DOUBLE refraction , *CRYSTAL whiskers , *POLARIMETRY , *TEMPERATURE , *WAVELENGTHS , *THERMAL expansion - Abstract
We designed, fabricated, and characterized birefringent holey fibers with zero polarimetric sensitivity to temperature. The sensitivity measurements were carried out in a wide spectral range of 0.68–1.55 μm in fibers with different hole and pitch values and with birefringence induced by a pair of large holes adjacent to the core. Our results show that zero sensitivity to temperature can be obtained at certain wavelengths for the bare fibers with properly adjusted geometrical parameters. Moreover, the spectral measurements of the sensitivity to temperature are in good agreement with the modeling results for all the investigated fibers. [ABSTRACT FROM AUTHOR]
- Published
- 2009
- Full Text
- View/download PDF
20. Stabilization of Fiber Bragg Gratings Against Gamma Radiation.
- Author
-
Gusarov, A., Vasillev, S., Medvedkov, O., Mckenzie, L., and Berghmans, F.
- Subjects
- *
RADIATION , *GAMMA rays , *SPECTRUM analysis , *BRAGG gratings , *RADIATION tolerance , *OPTICAL fibers - Abstract
The effect of gamma-radiation on the spectral characteristics of FBGs has been studied experimentally. The FBGs were fabricated in optical fibers with a GeO2 concentration in the core in a range from several to 99 mol.%. Various pre- and post-fabrication treatments were applied with the aim to improve the radiation tolerance of the FBGs. The best result was obtained for a Type ha annealed grating written in SM310 fiber, where the Bragg peak shift saturated at a 12 pm level and an amplitude change of 0.04 dB with the maximal dose of about 50 kGy. [ABSTRACT FROM AUTHOR]
- Published
- 2008
- Full Text
- View/download PDF
21. Pulsed X-Ray and Continuous Gamma Radiation Effects on Erbium Doped Optical Fibers Properties.
- Author
-
Tortech, B., Gusarov, A., Van Uffelen, M., Bisutt, J., Girard, S., Ouerdane, Y., Boukenter, A., Meunier, J..-P., Berghmans, F., and Thierpont, H.
- Subjects
- *
OPTICAL fibers , *GAMMA rays , *DOPED semiconductors , *X-rays , *IONIZING radiation , *IONS - Abstract
The radiation responses of two erbium doped fibers are studied in harsh pulsed X-ray and gamma ray environments. Their transient and continuous responses were measured in the near-infrared spectral range. The online transmission measurement of Radiation-Induced Attenuation (RIA) show no detectable change in the 1450-1600 nm erbium-ions-absorption domain, whereas the background losses from the silica-based host matrix are strongly increased by the creation of point defects. For both harsh environments, the rare-earth doped samples exhibit higher RIA levels compared than standard passive optical fibers. From all our measurements, we proposed that the main contribution to the induced losses is due to the radiation-induced changes of the host matrix rather than changes related to erbium ions. Photo-luminescence analyses confirm the generation of NBOHC in erbium doped fibers and suggest the existence of energy transfer between the radiation-induced point defects and the Er3+ ions. [ABSTRACT FROM AUTHOR]
- Published
- 2007
- Full Text
- View/download PDF
22. Proton- and Gamma-Induced Effects on Erbium-Doped Optical Fibers.
- Author
-
Girard, S., Tortech, B., Régnier, E., Van Uffelen, M., Gusarov, A., Ouerdane, Y., Baggio, J., Paillet, P., Ferlet-Cavrois, V., Boukenter, A., Meunier, J.-P., Berghmans, F., Schwank, J. R., Shaneyfelt, M. R., Felix, J. A., Blackmore, E. W., and Thienpont, H.
- Subjects
- *
ERBIUM , *PROTONS , *OPTICAL fibers , *RADIATION , *RADIATION exposure , *GERMANIUM - Abstract
We characterized the responses of three erbium-doped fibers with slightly different concentrations of rare-earth ions (240-290 ppm) and Al2O3 (7-10 wt.%) during proton and γ-ray exposures. We have simultaneously measured the radiation-induced attenuation (RIA) around the Er3+ ion pumping wavelength (980 nm) and the associated changes of the Er3+ emission around 1530 nm. The three erbium-doped fibers show similar radiation responses. All fibers exhibit RIA levels between 9 × 10-3 and 1.7 × 10-2 dB m-1 Gy-1 at 980 nm and between 4 × 10-3 and 1.1 × 10-2 dB m-1 Gy-1 at 1530 nm. Protons and -y-rays lead to similar radiation damages, with small differences between the protons of different energies (50 MeV and 105 MeV). Furthermore, we have performed online measurements of the spectral dependence of RIA from 600 to 1600 nm and offline measurements from 1200 to 2400 nm. The three fibers exhibit the same spectral response. Losses decrease monotonically from the visible to the infrared part of the spectrum. We have performed spectral decomposition of these RIA curves with the help of absorption bands previously associated with radiation-induced point defects. Our analysis shows that the main part of the RIA (600-1700 nm) in erbium-doped glass can be explained by the generation of Al-related point defects. The other defects related to the germanium and phosphorus doping of the silica seem to have a lower contribution to the induced losses. The Er3+ ion properties seem to be mainly unaffected by proton exposure, suggesting a solvation shell around the Er3+ ion formed by Al2O3 species. [ABSTRACT FROM AUTHOR]
- Published
- 2007
- Full Text
- View/download PDF
23. An active vacuum general-purpose radiation test facility for assessment of ceramic insulators and diagnostic components
- Author
-
Ooms, H., Hodgson, E., Decréton, M., Brichard, B., Hendrickx, S., Van Ierschot, C., and Berghmans, F.
- Subjects
- *
RADIATION , *IRRADIATION , *VACUUM , *ELECTRIC discharges - Abstract
Abstract: Diagnostic components and heating and current drive systems will be used within the vacuum vessel of the future fusion reactors, and especially in ITER. They will have to withstand harsh conditions in terms of neutron and gamma radiations, temperatures, applied voltages and vacuum. In order to study the degradation phenomena of the insulation and window materials and to qualify prototype systems, a representative environment must be available to perform reliable evaluation tests. A multi-purpose irradiation facility has been therefore designed to fit the BR2 experimental fission reactor in Mol, Belgium. This reloadable facility allows a full control of the irradiation conditions (up to 1014ncm−2 s−1 and 500°C) in a vacuum or inert atmosphere, with in-situ bias and measurement capabilities. [Copyright &y& Elsevier]
- Published
- 2007
- Full Text
- View/download PDF
24. Radiation assessment of hydrogen-loaded aluminium-coated pure silica core fibres for ITER plasma diagnostic applications
- Author
-
Brichard, B., Tomashuk, A.L., Ooms, H., Bogatyrjov, V.A., Klyamkin, S.N., Fernandez, A.F., Berghmans, F., and Decréton, M.
- Subjects
- *
ALUMINUM , *PLANT products , *SILICON compounds , *OPTICAL fibers - Abstract
Abstract: We report on the radiation assessment of hydrogenated aluminium coated 200μm pure silica core fibres. It is experimentally demonstrated that hydrogen protected the fibres against the radiation-induced absorption. With such appropriate hydrogen treatment the fibres can survive the ITER radiation environment in the vicinity of the labyrinth region of the tokamak reactor. [Copyright &y& Elsevier]
- Published
- 2007
- Full Text
- View/download PDF
25. Experimental developments towards an ITER thermography diagnostic
- Author
-
Reichle, R., Brichard, B., Escourbiac, F., Gardarein, J.L., Hernandez, D., Le Niliot, C., Rigollet, F., Serra, J.J., Badie, J.M., van Ierschot, S., Jouve, M., Martinez, S., Ooms, H., Pocheau, C., Rauber, X., Sans, J.L., Scheer, E., Berghmans, F., and Decréton, M.
- Subjects
- *
THERMOGRAPHY , *OPTICAL fibers , *EMISSIVITY , *TUNGSTEN - Abstract
Abstract: In the course of the development of a concept for a spectrally resolving thermography diagnostic for the ITER divertor using optical fibres experimental development work has been carried out in three different areas. Firstly ZrF4 fibres and hollow fibres (silica capillaries with internal AG/AgJ coating) were tested in a Co60 irradiation facility under γ irradiation up to doses of 5kGy and 27kGy, respectively. The ZrF4 fibres suffered more radiation induced degradation (>1db/m) then the hollow fibres (0–0.4db/m). Secondly multi-colour pyroreflectometry is being developed towards tokamak applicability. The emissivity and temperature of tungsten samples were measured in the range of 700–1500°C. The angular working range for off normal observation of the method was 20–30°. The working distance of the method has been be increased from cm to the m range. Finally, encouraging preliminary results have been obtained concerning the application of pulsed and modulated active thermography. [Copyright &y& Elsevier]
- Published
- 2007
- Full Text
- View/download PDF
26. Gamma radiation induced loss in erbium doped optical fibers
- Author
-
Tortech, B., Van Uffelen, M., Gusarov, A., Ouerdane, Y., Boukenter, A., Meunier, J.-P., Berghmans, F., and Thienpont, H.
- Subjects
- *
RADIATION , *IRRADIATION , *OPTICAL fibers , *FIBER optics - Abstract
Abstract: Several single mode silica-based fibers with different levels of erbium concentrations have been tested under 60Co gamma radiation. Irradiation has been performed at a dose-rate of ∼30Gy/h to a total dose of ∼2kGy. Transmission spectra were measured in situ in a spectral range from 1250 to 1630nm. The measurements show no detectable change in the Er-ions luminescence and absorption spectrum profiles, while a significant (∼dB/m/kGy at 1530nm) increase in transmission losses is attributed to the silica host matrix modifications. This conclusion is drawn based on the post-irradiation photo-luminescence analyzes realized with a confocal micro-spectrometer (514.5nm excitation, P ∼2mW). [Copyright &y& Elsevier]
- Published
- 2007
- Full Text
- View/download PDF
27. Reduction of the radiation-induced absorption in hydrogenated pure silica core fibres irradiated in situ with γ-rays
- Author
-
Brichard, B., Tomashuk, A.L., Bogatyrjov, V.A., Fernandez, A.F., Klyamkin, S.N., Girard, S., and Berghmans, F.
- Subjects
- *
ABSORPTION , *RADIATION , *SILICON compounds , *NONMETALS - Abstract
Abstract: We studied the efficiency of a hydrogen-treatment in different pure silica core fibres irradiated by γ-ray in an attempt to decrease the radiation-induced absorption (RIA). It is observed that the effect of hydrogen already reduces the drawing-induced band commonly observed in low-OH fibres. During irradiation we observe a large increase of the radiation-induced OH growth with a corresponding significant reduction of the radiation-induced absorption at 0.63μm. The presence of hydrogen also reduces the transient radiation-induced absorption at 0.7μm sometimes observed in low-OH/low-chlorine fibres and believed to pertain to self-trapped holes (STHs). [Copyright &y& Elsevier]
- Published
- 2007
- Full Text
- View/download PDF
28. High-Vacuum Gamma Irradiation Facilities for Synergistic Effects Testing on Optoelectronic Components and Materials.
- Author
-
Fernandez Fernandez, A., Brichard, B., Ooms, H., and Berghmans, F.
- Subjects
- *
OPTOELECTRONIC devices , *NUCLEAR research , *OPTICAL instruments , *OPTICAL computer equipment , *FIBER optics , *LOGIC circuits , *RANDOM access memory , *DIGITAL electronics , *SWITCHING circuits , *SWITCHING theory - Abstract
The assessment of the durability of candidate space components and materials requires the use of ground laboratory testing facilities when no reliable information exists in the published literature. Accelerated tests simulating the radiation/temperature/vacuum environment need to be performed to investigate possible synergistic degradation effects. An irradiation chamber combining high vacuum and thermal cycling with a large range of gamma dose rates has been designed and constructed for this purpose at SCK·CEN, the Belgian Nuclear Research Center. The irradiation chamber module with actively-controlled vacuum is designed to fit in our gamma irradiation facilities. The vacuum irradiation module operates in the high-vacuum regime even in the presence of moderate outgassing from polymer materials. A pressure of 10-5 mbar can be routinely achieved but lower pressure can be obtained in the case of inert and mineral materials. In addition to the facility description, our paper discusses preliminary results of radiation-assisted outgassing of common polymers obtained using this new vacuum irradiation module. [ABSTRACT FROM AUTHOR]
- Published
- 2006
- Full Text
- View/download PDF
29. Kinetic approach to the decomposition of radiation-induced absorption spectra
- Author
-
Gusarov, A., Doyle, D., Glebov, L., and Berghmans, F.
- Subjects
- *
MOLECULAR spectroscopy , *DATA transmission systems , *DIGITAL communications , *ABSORPTION spectra - Abstract
Abstract: We propose a kinetic approach to the decomposition of the radiation-induced absorption spectra into individual Gaussian absorption bands. It is based on the correlated analysis of a series of induced absorption spectra obtained in the course of multi-step irradiation and during room temperature long-term post-radiation annealing. The methodology is demonstrated using data on Co60 gamma irradiated samples of commercial boro-silicate glass N-BK7 from SCHOTT. We show that physically meaningful spectroscopic parameters of absorption bands can be obtained without a priori knowledge of the band peak position and bandwidth. [Copyright &y& Elsevier]
- Published
- 2006
- Full Text
- View/download PDF
30. SPICE Modelling of a Discrete COTS SiGe HBT for Digital Applications up to MGy Dose Levels.
- Author
-
Van Uffelen, M., Geboers, S., Leroux, P., and Berghmans, F.
- Subjects
- *
THERMONUCLEAR fuels , *RADIATION , *GAMMA rays , *ELECTROMAGNETIC waves , *ELECTRONICS , *ELECTRIC circuits , *PHOTONICS , *BIPOLAR transistors , *HETEROJUNCTIONS - Abstract
Future maintenance tasks of the International Experimental Thermonuclear fusion Reactor (ITER) will require communication links between the remotely operated equipment in the reactor vessel and the control room, that are radiation tolerant up to MGy dose levels. We therefore assessed the DC behaviour of a COTS SiGe heterojunction bipolar transistor (HBT) under gamma radiation up to more than 4 MGy. The DC current gain (β) presents a limited loss of about 30% for a base current of 100 μA. Our in-situ measurements allowed us to adapt the manufacturer's SPICE model and account for these radiation effects. Circuit-hardened driving electronics for both photonic transmitters and receivers can hence be designed. [ABSTRACT FROM AUTHOR]
- Published
- 2006
- Full Text
- View/download PDF
31. Comparative Study of Pulsed γ-Ray and 7-Ray Radiation-Induced Effects in Pure-Silica-Core Optical Fibers.
- Author
-
Girard, S., Brichard, B., Baggio, J., Berghmans, F., and Decréton, M.
- Subjects
- *
OPTICAL fibers , *PULSED radiation , *COLOR centers (Crystals) , *RADIATION , *RADIATION tolerance , *ALPHA rays , *OPTICAL waveguides , *HYDROXYL group , *PLASMA gases - Abstract
We have investigated the variation of the optical absorption induced by pulsed (dose rate > 108 rad/s) and continuous (<50 rad/s) γ-ray exposures in pure-silica-core optical fibers. Tested multimode waveguides, designed with well-defined concentrations of hydroxyl groups and chlorine impurity, are possible candidates for integration in the plasma diagnostics of LMJ and ITER facilities. We evaluated their radiation-tolerance to low dose levels (<5 × 104 rad) in the visible and near-infrared parts of the spectrum. We measure the time dependent changes (10-9–10-1 s) of the radiation-induced attenuation (RIA) at fixed wavelengths and we complete these measurements with a spectral (450–1100 nm) analysis of these losses in the time range from 10-2 to 10³ s. We compared the responses obtained under transient exposures with measurements done at same dose levels (5 × 10³ rad) with lower dose rate (<10² rad/s). We showed that the radiation-induced changes are strongly dose rate dependent for this kind of optical fibers. Depending on the hydroxyl group concentration in the silica-glass, different point defects are shown to alter the fiber transmission after both irradiation types. The self-trapped holes play a particular role in the transient responses of optical fibers whereas non-bridging oxygen hole centers are mainly responsible for γ-ray radiation-induced losses. The consequences of these different behaviors for the integration of optical fibers in the LMJ are discussed. [ABSTRACT FROM AUTHOR]
- Published
- 2006
- Full Text
- View/download PDF
32. Transient optical absorption in pulsed-X-ray-irradiated pure-silica-core optical fibers: Influence of self-trapped holes
- Author
-
Girard, S., Griscom, D.L., Baggio, J., Brichard, B., and Berghmans, F.
- Subjects
- *
SILICA , *OPTICAL fibers , *ION traps , *SPECTRUM analysis - Abstract
Abstract: We investigated pulsed-X-ray-induced attenuation in two pure-silica-core (PSC) optical fibers with low-chloride (Cl) and different hydroxyl (OH) contents. We measured at room temperature the temporal (100ms–1000s) and spectral (0.73–3.1eV) variation of the induced optical absorption after a 1MeV X-ray pulse in both low- and high-OH PSC multi-mode fiber samples. A component of the transient loss in the low-OH sample was found to comprise absorption bands at 1.63 and 1.88eV (760 and 660nm) arising from self-trapped holes (STHs). Already known to be unstable at room temperature, STHs appear to play a key role in the transient responses of low-OH/low-Cl pure-silica-core fibers in the visible/near-infrared part of the spectrum. [Copyright &y& Elsevier]
- Published
- 2006
- Full Text
- View/download PDF
33. Radiation-Tolerant Raman Distributed Temperature Monitoring System for Large Nuclear Infrastructures.
- Author
-
Fernandez, A. Fernandez, Rodeghiero, P., Brichard, B., Berghmans, F., Hartog, A. H., Hughes, P., Williams, K., and Leach, A. P.
- Subjects
- *
RADIATION , *RAMAN spectroscopy , *NUCLEAR energy , *OPTICAL fibers , *GAMMA ray spectrometry , *TEMPERATURE measuring instruments , *NUCLEAR power plants , *GAMMA rays - Abstract
Raman Distributed Temperature Sensors (RDTS) are attractive for the monitoring of large structures in nuclear power plants such as containment structures and coolant loop systems. We demonstrate the high radiation tolerance of a Raman distributed fiber optic temperature sensor, up to total gamma doses in excess of 300 kGy, using a double-ended configuration and commercially-available optical fibers. [ABSTRACT FROM AUTHOR]
- Published
- 2005
- Full Text
- View/download PDF
34. In situ in-reactor testing of fusion materials and components
- Author
-
Gusarov, A., Vermeeren, L., Brichard, B., van Nieuwenhove, R., Fernandez, A. Fernandez, Ooms, H., Decréton, M., and Berghmans, F.
- Subjects
- *
RADIATION , *NUCLEAR reactors , *RADIOACTIVITY , *NEUTRON sources - Abstract
Abstract: Radiation hardness assurance for ITER is based on extensive radiation testing. To be representative, these tests must involve an in situ follow-up of the radiation induced changes. SCK·CEN—the Belgian Nuclear Research Center is operating different irradiation facilities with broad possibilities of environmental control and on-line instrumentation. We describe those facilities and outline several recently completed and on-going experiments to illustrate capabilities for testing under conditions relevant for ITER. [Copyright &y& Elsevier]
- Published
- 2005
- Full Text
- View/download PDF
35. Temperature and pressure sensitivities of the highly birefringent photonic crystal fiber with core asymmetry.
- Author
-
Nasilowski, T., Martynkien, T., Statkiewicz, G., Szpulak, M., Olszewski, J., Golojuch, G., Urbanczyk, W., Wojcik, J., Mergo, P., Makara, M., Berghmans, F., and Thienpont, H.
- Subjects
- *
CRYSTAL whiskers , *OPTICAL fibers , *FIBERS , *DOUBLE refraction , *PHOTONICS , *OPTICS - Abstract
We investigated a particular design of a highly birefringent PCF with attractive features for pressure sensing applications. A plane-wave method together with the finite element method were used to numerically calculate phase and group modal birefringence, pressure and temperature sensitivities of our fiber. The simulation results together with the experiments demonstrate a considerable difference between a very high phase birefringence ( B ∼ 10−3) and a very low negative group birefringence ( G −10−3). Our fiber exhibits a low and positive temperature sensitivity ( KT < 0.1 rad/(K⋅m)), and relatively high and negative mechanical (pressure) sensitivity ( Kp ≤ −10 rad/(MPa⋅m)), which supports its possible use as a mechanical sensor that does not require any temperature compensation. [ABSTRACT FROM AUTHOR]
- Published
- 2005
- Full Text
- View/download PDF
36. Gamma Dosimetry Using Red 4034 Harwell Dosimeters in Mixed Fission Neutrons and Gamma Environments.
- Author
-
Fernandez, A. Fernandez, Brichard, B., Ooms, H., van Nieuwenhove, R., and Berghmans, F.
- Subjects
- *
GAMMA rays , *RADIATION tolerance , *MONTE Carlo method , *RADIOBIOLOGY , *NUCLEAR reactors , *NUCLEAR energy , *IONIZING radiation - Abstract
The radiation tolerance testing of materials or opto-electronic components in a nuclear reactor requires a careful determination of the different components of the mixed gamma-neutron field. While the characterization of the neutron field can be performed using, for example, activation foils and validated by Monte-Carlo computation codes, the experimental measurement of the in-reactor gamma dose rate requires the use of costly ionization chambers. In this paper, we evaluate the possibility of using Red Perspex from Hanvell Technologies for routine gamma dosimetry in mixed gamma neutron field. Self-powered gamma detectors and ionization chambers were used as reference dosimeters. We show that the accuracy of the Red 4034 dosimeter's is better than 10% in mixed gamma-neutron fields. [ABSTRACT FROM AUTHOR]
- Published
- 2005
- Full Text
- View/download PDF
37. Gamma Radiation Effects in Er-Doped Silica Fibers.
- Author
-
Van Uffelen, M., Girard, S., Goutaland, F., Gusarov, A., Brichard, B., and Berghmans, F.
- Subjects
- *
RADIATION , *GAMMA rays , *ELECTROMAGNETIC waves , *IONIZING radiation , *PHOTOLUMINESCENCE , *SILICA - Abstract
The radiation behavior of a commercially available Er-doped fiber is evaluated under varying gamma dose rates with in-situ spectral loss measurements. Complementary post-irradiation photoluminescence measurements allow us to better under- stand the radiation effects. Our results suggest that the microscopic enviromnent of the Er3+ ions is not much affected by the gamma irradiation, unlike the host matrix. We discuss the impact for potential applications of these commercially available fibers in radiation environments. [ABSTRACT FROM AUTHOR]
- Published
- 2004
- Full Text
- View/download PDF
38. Radiation-hardening techniques of dedicated optical fibres used in plasma diagnostic systems in ITER
- Author
-
Brichard, B., Fernandez Fernandez, A., Ooms, H., Berghmans, F., Decréton, M., Tomashuk, A., Klyamkin, S., Zabezhailov, M., Nikolin, I., Bogatyrjov, V., Hodgson, E., Kakuta, T., Shikama, T., Nishitani, T., Costley, A., and Vayakis, G.
- Subjects
- *
RADIATION hardening (Electronics) , *OPTICAL fibers , *PLASMA diagnostics , *FUSION reactors , *BACKGROUND radiation , *LIGHT absorption , *NUCLEAR reactors , *LUMINESCENCE - Abstract
This paper addresses the particular need to develop suitable fabrication techniques of glasses to improve the radiation-resistance and extend the lifetime of optical fibres in high radiation background. Two radiation hardening techniques based on hydrogen and fluorine doping of glass have been applied on step index pure silica core optical fibres. The radiation-induced optical absorption and luminescence have been measured in gamma and fission reactor irradiation conditions at SCKCEN, Mol Belgium. The experimental results show that the lowest optical absorption is achieved in the hydrogen-treated fibre sample. However, the luminescence effect remains significant in any type of fibre and cannot be reduced by the investigated radiation hardening techniques. [Copyright &y& Elsevier]
- Published
- 2004
- Full Text
- View/download PDF
39. Dependence of the POR and NBOHC Defects as Function of the Dose in Hydrogen-Treated and Untreated KU1 Glass Fibers.
- Author
-
Brichard, Benoit, Fernandez, Alberto Fernandez, Ooms, Hans, Borgermans, P., and Berghmans, F.
- Subjects
- *
ATTENUATION (Physics) , *HYDROGEN , *RADIATION , *OPTICAL fibers , *DECONVOLUTION (Mathematics) , *SPECTRUM analysis , *LIGHT absorption - Abstract
We evaluated the performances of the hydrogen-loading technique to reduce the radiation-induced absorption in optical fibers in the visible part of the spectrum. A reduction factor as large as one order of magnitude can be obtained in high dose-rate regime. Based on a spectral deconvolution method, we showed that hydrogen preferentially interacts with NBOHC defects while the number of POR defects is not affected. [ABSTRACT FROM AUTHOR]
- Published
- 2003
- Full Text
- View/download PDF
40. Radiation tolerance qualification for maintenance tasks in the future fusion reactors: from fibre-optic components to robust data links
- Author
-
Van Uffelen, M., Fernandez, A. Fernandez, Brichard, B., Berghmans, F., and Decréton, M.
- Subjects
- *
FUSION reactors , *REMOTE handling (Radioactive substances) , *OPTICS , *RADIATION - Abstract
The future International Thermonuclear Experimental Reactor (ITER) requires remote handling tools for its maintenance that will operate in a harsh environment. The numerous instrumentation cables for this maintenance equipment call for (de)multiplexing solutions, in order to reduce the umbilical size. Fibre-optic data links, using commercial-off-the-shelf (COTS) components, are seriously considered as a radiation tolerant solution, offering wavelength encoded multiplexing possibilities. However, an adapted modus operandi for a reliable assessment of this evolving technology is needed, to enable their long-term implementation in a radiation environment. In this paper, we present a methodology towards qualification methods for these instrumentation data links, and illustrate it with results obtained for different individual components. These results should enable the future design of robust architectures for communication links. [Copyright &y& Elsevier]
- Published
- 2003
- Full Text
- View/download PDF
41. Index and density changes induced by proton radiation in lanthanum crown glass.
- Author
-
Gusarov, A., Doyle, D., Hermanne, A., and Berghmans, F.
- Subjects
- *
LANTHANUM , *OPTICAL glass , *REFRACTIVE index , *PROTONS - Abstract
We studied the refractive index and density changes in cerium-doped lanthanum crown glass irradiated in air with 38.5 MeV protons. At a low proton fluence, the index change is linear with dose, and reaches 2.4x10[sup -5] at 2.7x10[sup 12] p/cm[sup 2] (0.65 Mrad dose). The rate of index change decreases with the proton fluence, but at high total dose (10[sup 14] p/cm[sup 2]) radiation-induced surface dilatation and birefringence start to appear. Our results show that the present concept of radiation-hard optical glass should be revised and that a high dose of proton radiation can produce index changes sufficient for the fabrication of integrated optical devices. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]
- Published
- 2001
- Full Text
- View/download PDF
Catalog
Discovery Service for Jio Institute Digital Library
For full access to our library's resources, please sign in.