Search

We evaluated the radiation tolerance of volume holographic elements written in photo-thermo refractive glass. To do so these elements were exposed to Co60 gamma-radiation and 60 MeV protons. At 10 kGy dose levels a high stability has been observed. Our results confirm that such components can operate in a space radiation environment. [ABSTRACT FROM AUTHOR]

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]

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]

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]

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]

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]

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.