Search results for "optical"
showing 10 items of 7671 documents
Understanding tungsten erosion during inter/intra-ELM periods in He-dominated JET-ILW plasmas
2021
Tungsten erosion was quantified during inter/intra-ELM periods in He-dominated JET-ILW plasmas by optical emission spectroscopy. The intra-ELM tungsten sputtering in helium plasmas, which dominates the total W source, prevails by a factor of about 4 over inter-ELM sputtering in the investigated ELM frequency range from 90 Hz-120 Hz. He ions are mainly responsible for the W erosion during the ELMs in He plasmas. The strong in/out asymmetry of the ELM-induced W erosion is observed in He plasmas even at high ELM frequencies beyond 100 Hz. In Ohmic/L-mode plasmas and during the H-mode inter-ELM plasma phases both He2+ and Be2+ ionic species are major contributors to the W erosion. Their contrib…
Optical limiters relying on VO2 phase transition in thin multilayer films
2022
We propose a self-activating optical limiter device based on phase transition of vanadium dioxide in thin multilayer films. The optimal geometry reduces the transmitted power by ~ 70% and shows a recovery time of 10 ns.
Lidar detection of carbon dioxide in volcanic plumes
2015
Volcanic gases give information on magmatic processes. In particular, anomalous releases of carbon dioxide precede volcanic eruptions. Up to now, this gas has been measured in volcanic plumes with conventional measurements that imply the severe risks of local sampling and can last many hours. For these reasons and for the great advantages of laser sensing, the thorough development of volcanic lidar has been undertaken at the Diagnostics and Metrology Laboratory (UTAPRAD-DIM) of the Italian National Agency for New Technologies, Energy and Sustainable Economic Development (ENEA). In fact, lidar profiling allows one to scan remotely volcanic plumes in a fast and continuous way, and with high s…
Waste heat recovery from a marine waste incinerator using a thermoelectric generator
2012
Published version of an article published in the journal: Journal of Electronic Materials. Also available from the publisher at: http://dx.doi.org/10.1007/s11664-012-2009-6 A marine waste incinerator has been evaluated for waste heat harvesting using thermoelectric generators (TEG). The application has been evaluated using mathematical modeling to optimize the heat exchanger and some vital design parameters of the TEG. The calculation shows that it is possible to extract 58 kW el at a price of 6.6 US$/W from an 850-kW th incinerator when optimizing for maximum power. However, minimizing the cost, it is possible to get 25 kW el at a price of 2.5 US$/W. A trade-off between the two targets lea…
Analytical results for 2-D non-rectilinear waveguides based on a Green's function
2008
We consider the problem of wave propagation for a 2-D rectilinear optical waveguide which presents some perturbation. We construct a mathematical framework to study such a problem and prove the existence of a solution for the case of small imperfections. Our results are based on the knowledge of a Green's function for the rectilinear case.
Synergistic effect of W incorporation and pulsed current mode on wear and tribocorrosion resistance of coatings grown by plasma electrolytic oxidatio…
2019
Ceramic coatings were grown by plasma electrolytic oxidation on 7075 Al alloy using unipolar and bipolar pulsed current waveforms with 20 and 40% cathodic duty cycles, from a silicate-based bath without and with the addition of Na2WO4. Pancake-like morphology was dominant on the coatings grown by unipolar waveform, while the bipolar waveforms promoted volcano-like morphology, increased the roughness of the coating surface and the formation of more compact layers. The coatings produced using the bipolar waveforms provided higher resistances toward both tribocorrosion and dry sliding conditions, while further improvement was achieved by the presence of tungsten. The coatings produced in tungs…
Computer Networks
2018
This book constitutes the thoroughly refereed proceedings of the 25th International Conference on Computer Networks, CN 2018, held in Gliwice, Poland, in June 2018. The 34 full papers presented were carefully reviewed and selected from 86 submissions. They are organized in topical sections on computer networks; teleinformatics and telecommunications; queueing theory; cybersecurity and quality service.
The Large Observatory For x-ray Timing
2014
The Large Observatory For x-ray Timing (LOFT) was studied within ESA M3 Cosmic Vision framework and participated in the final down-selection for a launch slot in 2022-2024. Thanks to the unprecedented combination of effective area and spectral resolution of its main instrument, LOFT will study the behaviour of matter under extreme conditions, such as the strong gravitational field in the innermost regions of accretion flows close to black holes and neutron stars, and the supra-nuclear densities in the interior of neutron stars. The science payload is based on a Large Area Detector (LAD, 10 m 2 effective area, 2-30 keV, 240 eV spectral resolution, 1 deg collimated field of view) and a WideFi…
Hydrogels for Three-Dimensional Ionizing-Radiation Dosimetry
2021
Radiation-sensitive gels are among the most recent and promising developments for radiation therapy (RT) dosimetry. RT dosimetry has the twofold goal of ensuring the quality of the treatment and the radiation protection of the patient. Benchmark dosimetry for acceptance testing and commissioning of RT systems is still based on ionization chambers. However, even the smallest chambers cannot resolve the steep dose gradients of up to 30–50% per mm generated with the most advanced techniques. While a multitude of systems based, e.g., on luminescence, silicon diodes and radiochromic materials have been developed, they do not allow the truly continuous 3D dose measurements offered by radiation-se…
Experimental study of MMI structures in a switchable continuous-wave thulium-doped all-fiber laser
2022
Switchable multi-wavelength laser emission from a thulium-doped all-fiber laser is reported by implementing a tapered and a non-tapered multi-modal interference (MMI) filters. The MMI structure relies on a coreless optical fiber spliced in between two single-mode optical fibers. For the non-tapered case, a minimum insertion loss of 12.60 dB is achieved around the 2-μm region, from which stable generation of commutable dual-wavelength emission at 1986.34 nm and 2017.38 nm is obtained. On the other hand, the tapered MMI structure performs a minimum insertion loss of 8.74 dB at the 2-μm region, allowing a stable triple-wavelength emission at 1995.4 nm, 2013.3 nm, and 2038.3 nm. In addition, co…