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Galvanic process for Cu-infiltration of W fibre-reinforced heat sinks
Get PDFA challenging aspect in view of the realization of a future magnetic confinement fusion reactor is the design and manufacture of highly loaded divertor target plasma-facing components (PFCs) which have to sustain intense particle, heat and neutron fluxes. In this context, tungsten-copper (W-Cu) composites are currently being investigated as potentially advanced heat sink materials for PFCs. The development and manufacture of W-Cu composite pipes, which are bonded to tungsten monoblocks, poses new challenges in terms of manufacturing and accuracy. A new approach is proposed to produce the W-Cu composite pipe. The proposed alternative is to directly infiltrate tungsten fibers with galvanic copper instead of by copper infiltration in an furnace. The paper presents the status of the development to better assess the impact of various parameters affecting the galvanic process. Different braid thicknesses (3 and 6 layers) and their orientation (70° and 80°) have been tested. The effects of the electrolytic bath circulation, the variation in the braid material (porosities), and the electrolytic exchange by using pulsating direct current on the diffusion in the braid have been investigated. The influence of the passivation mode has also been carefully analyzed because in the case of a strong passivation copper only grows too quickly outwards from the core and not onto the tungsten braid
Innovative Concepts in the DTT Neutral Beam Injector
No full textThe main purpose of the divertor tokamak test (DTT) facility is to study alternative solutions to mitigate the issue of the power exhaust, under integrated physics and technical conditions relevant to ITER and DEMO. One of the most complex and innovative subsystems of the entire project is certainly the negative-ion-based neutral beam injector (NBI), meant to inject 10 MW of auxiliary power with a beam of 510 keV deuterium neutrals. This contribution describes the conceptual design of the beamline for the DTT NBI system, with a particular focus on the innovative technical solutions adopted to fulfill the requirements and maximize the performance. The DTT NBI is required to operate with high efficiency in several operating scenarios, covering a large range of beam energies, between 10% and 100% of the nominal value (510 keV). To reach this challenging goal, an innovative accelerator design, the spherical and lemon hyperlens grids (SLHGs), has been developed. The implementation of this design concept of the accelerator has recently become possible thanks to recent improvements in additive manufacturing (AM) technology. Another original aspect of the DTT NBI, compared to existing devices, regards the vacuum pumping system, which will be based on nonevaporable getter (NEG) pumps. This will represent the first application of the NEG technology to an NBI for the heating and current drive system of a fusion experiment, with a possible simplification of the overall construction, with respect to typical solutions based on cryogenic pumps. Other innovative solutions are the cylindrical sawtooth structure (CSS) for the neutralizer panels and the stray field shielding system (SFSS) with encapsulated neutralizer. This article provides an overview of the injector for DTT NBI with a particular focus on innovative technical solutions
Italian Potential of Residual Biogenic Resources for Energy-Driven Biorefineries
No full textA reliable assessment of the availability of bioresources represents the first step to defining local value chains of particular interest. More than 190 and 50 Mt/y of bioresources are currently available in Europe and Italy, respectively, even if they are not fully valorized. The best end use of these feedstocks is strictly dependent on specific territorial/regional peculiarities, that consequently affect the products' final properties. In this work, the Italian web-GIS-based tool “Atlante delle biomasse” was used to determine the availability of many bioresources in Italy at the regional level. A lump classification criterion was used to categorize the available biomasses, and, then, an optimization algorithm based on a process superstructure was applied to find out the available fraction of bioresources, the amount of biofuels potentially obtainable and, consequently, the regional fuel demand coverable by biofuels. In particular, only the energy-self-sufficient technologies with higher TRLs were considered in the mathematical model. The integration between the different selected bioresources led to three biofuels to be considered, evaluating the percentage of biofuel demand that could be covered for each Italian region. The final potential production of biofuels derived from local bioresources in Italy settles down on the range 9 107 – 1.6 108 GJ/y covering about 5, 50, and 100 % of methane, biodiesel and bio-LPG demand respectively. Bio-LPG demand for all regions was to be considered completely satisfied, biodiesel production was also sufficient to cover high demands, on the other hand, low values of biomethane requirements coverable were obtained
Fire Risk Evaluation of the Internal Components of the Li-Ion Batteries
No full textThe advantages of Lithium-ion batteries (LIBs) are well known, anyway the LIBs are even considered hazardous products. In fact, outside the safety windows the Li-ion cells can undergo to an abuse that leads to the degradation of the internal components with the release of gases, vapour, and solid products. The reactivity of the LIBs and the relative products composition is strictly correlated to the chemical composition of the internal components. Because of a lack of regulation, safety data sheets (SDSs) of Li-ion cells are not mandatory but, generally they are available. However, there is a gap between the information reported in the SDS and the internal chemical composition, and usually the quantity of components is expressed as a range of weight percentages, and the chemical composition is not well specified. The most common lack of information concerns the electrolyte, which is usually defined as a mixture of organic carbonates without reporting the type of solvents (e.g., dimethyl carbonate, diethyl carbonate, and ethylene carbonate), the ratio between these components, and possible additives. The aim of this work was to characterize the internal components of various cylindrical 18650 cells available on the market, i.e., cell with Lithium Nickel Cobalt Aluminium Oxide (NCA) as cathode and graphite (C) or Lithium Titanate Oxide (LTO) as anode, and cells with Lithium Iron Phosphate (LFP) as cathode and C as anode. For this purpose, the cells were disassembled in a glovebox filled with argon (O2 and H2O ≤ 0.1 ppm) and then the different components were analysed by various techniques to define their chemical composition, i.e., metals of the electrodes by ICP-OES, the electrolyte by GC-FID and SPME-GC-MS, and the separator by ATR-FT-IR and DSC. The identification of those compounds is fundamental to understand the reactions occurring inside the cells and to evaluate the risks for human health and environment
Innovative graph-based video processing methodology for collapse early warning of historic masonry building
No full textIn the present study an innovative video processing methodology is proposed for application to vibration data of historic masonry structures. The proposed methodology is based on graph theory and topology analysis applied to magnified videos in search of effective parameters for early-warning signals before the collapse of structures in case of earthquakes. The proposed method was validated through seismic tests of a brick-masonry mockup representing a vault of the mosque in the Palace of the Dey, Algiers. In particular, the seismic tests were carried out at increasing earthquake intensity up to the final collapse of the mockup. After processing the videos of the seismic tests by motion magnification method, the magnified video frames were transformed into a graph of the structure. Finally, several graph indices were calculated and monitored during the vibration. The monitored parameters were analyzed in search of potential threshold values suitable to generate an early warning signal. In particular, the inverse algebraic connectivity provided an early warning signal in the order of a few seconds before collapse. This was validated by comparison with an analogous signal provided at similar time by an accurate displacement lab measurements system based on optical markers positioned at several points of the tested mock-up
The CompactLight Design Study
No full textCompactLight is a Design Study funded by the European Union under theHorizon 2020 research and innovation funding programme, with Grant Agreement No. 777431.CompactLight was conducted by an International Collaboration of 23 internationallaboratories and academic institutions, three private companies, and five third parties.The project, which started in January 2018 with a duration of 48 months, aimed to designan innovative, compact, and cost-effective hard X-ray FEL facility complemented by asoft X-ray source to pave the road for future compact accelerator-based facilities. Theresult is an accelerator that can be operated at up to 1 kHz pulse repetition rate,beyond today’s state of the art, using the latest concepts for high brightness electronphotoinjectors, very high gradient accelerating structures in X-band, and novelshort-period undulators. In this report, we summarize the main deliverable of theproject: the CompactLight Conceptual Design Report, which overviews the current statusof the design and addresses the main technological challenges
Inflationary quantum spectrum of the quasi-isotropic Universe
Get PDFWe investigate the quantum dynamics of the quasi-isotropic inflationary solution. This is achieved by deriving the Lagrangian and Hamiltonian for both the FLRW background and the inhomogeneous correction, via an expansion of the Einstein–Hilbert action up to second order in the perturbation amplitudes. Then we implement a semiclassical WKB scenario for which the inhomogeneous component of the Universe is treated as a “small” quantum subsystem, evolving on the classical isotropic background. Starting from the Wheeler–DeWitt equation, we recover a Schrödinger dynamics for the perturbations, in which the time dependence of the wave function emerges thanks to the classicality of the background, and we solve it for an inflationary phase. The main result of this paper is to show that, while the scalar component of the power spectrum has the standard scale invariant profile, the tensor one results to be not constrained by the inflationary expansion, apart from an overall normalization factor which guarantees a small tensor-to-scalar ratio. This means that the spatial distribution of the quasi-isotropic correction to the metric remains preserved, with the consequence that some information about the pre-inflationary Universe survives to the de Sitter expansion
Structural Assessment of the DTT Cryostat Design
No full textThe article presents the status of DTT cryostat system and illustrates the structural verification activities performed to assess its mechanical response under various design load combinations. To this purpose, an FEM shell model of the cryostat has been developed including mechanical loads on the cryostat base due to Vacuum Vessel and Magnets, modeled as equivalent point mass. Anchoring of the base columns to the Tokamak basements has also been modeled. To verify the cryostat design, simulations have been carried out for the most critical VDEs and seismic load combinations. In addition, thermo-mechanical effects induced by both Vacuum Vessel and Magnets, on the cryostat base, have been investigated, for plasma operation and baking conditions. Further, buckling condition, under external pressure, and accidental overpressure conditions, have also been investigated
Low-impact thermal insulation materials for sustainable retrofitting: Potentialities and barriers from a literature review
No full textThe present study provides both an updated overview of the most recent studies about low environmental impact materials for building retrofitting and meta-analyses of the most important features, such as the thermal conductivity, allowing to evaluate their insulation potential against the diffused and recurrent conventional competitors. Specifically, 466 case studies about materials derived by co-production, wastes of other products and recycled ones have been selected and their thermal performances have been analysed. The materials have been clustered into homogeneous classes: lose materials and foams; structural materials; panels; finishing materials. The results show that some low environmental impact materials are characterized by thermal performances which can position them as materials able to contribute to building decarbonization, but little information can be found about other characteristics which can be crucial when the built environment is considered, such as durability, fire resistance, costs, and load resistance. Yet, these latter aspects may be investigated further when the material is considered to enter the prototyping phase whether in the academic or market context. The present study provides a base for discussion about the use of more environmentally friendly thermal insulation materials which in the coming years might represent a valid option for sustainable building renovation
Conceptual Design of the DTT ECRH High Voltage Power Supply System
No full textThe Divertor Tokamak Test (DTT) facility is a controlled thermonuclear fusion device, whose construction has started at the ENEA Research Center in Frascati, Italy, with the aim to study solutions to mitigate the issue of power exhaust in an integrated environment and operating conditions relevant for future fusion reactors. A power of 45 MW to the plasma is foreseen and provided by a mix of heating and current drive (HCD) systems comprising electron cyclotron resonance heating (ECRH), ion cyclotron resonance heating (ICRH), and neutral beam injector (NBI). DTT, in the first experimental phase, will exploit the ECRH system, including 16 radio frequency (RF) sources (gyrotrons) with potential collector depressed, each rated for 1 MW power, 170 GHz frequency, and 100 s pulse length. The RF sources are fed in pairs by a high voltage power supply (HVPS) set, composed of one main power supply (MPS) and two body power supplies (BPSs), one for each gyrotron, and by low-voltage (LV) power supplies dedicated to the operation of the auxiliaries of the gyrotrons. This work describes the conceptual design of the HVPS system, the evaluation that led to the definition of its main requirements and to the selection of a reference design. In addition, the novel concept is presented for a dummy load (DL) able to mimic the real gyrotrons operation in normal and abnormal conditions for testing an HVPS set