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Measurement of inclusive charged-particle jet production in pp and p-Pb collisions at (Formula presented)
No full textMeasurements of inclusive charged-particle jet production in pp and p-Pb collisions at center-of-mass energy per nucleon-nucleon collision sNN = 5.02 TeV and the corresponding nuclear modification factor RpPbchjet are presented, using data collected with the ALICE detector at the LHC. Jets are reconstructed in the central rapidity region |ηjet| < 0.5 from charged particles using the anti-kT algorithm with resolution parameters R = 0.2, 0.3, and 0.4. The pT-differential inclusive production cross section of charged-particle jets, as well as the corresponding cross section ratios, are reported for pp and p-Pb collisions in the transverse momentum range 10 < 140 GeV/c and 10 < 160 GeV/c, respectively, together with the nuclear modification factor RpPbchjet in the range 10 < 140 GeV/c. The analysis extends the pT range of the previously-reported charged-particle jet measurements by the ALICE Collaboration. The nuclear modification factor is found to be consistent with one and independent of the jet resolution parameter with the improved precision of this study, indicating that the possible influence of cold nuclear matter effects on the production cross section of charged-particle jets in p-Pb collisions at sNN = 5.02 TeV is smaller than the current precision. The obtained results are in agreement with other minimum bias jet measurements available for RHIC and LHC energies, and are well reproduced by the NLO perturbative QCD Powheg calculations with parton shower provided by Pythia8 as well as by Jetscape simulations
Development of dynamic sharing keys: Algorithms supporting management of renewable energy community and collective self consumption
Get PDFThe potential of sharing energy from production plants is characterized as a new paradigm for the production and consumption of energy from renewable sources. The emergence of Renewable Energy Communities (REC) and Collective Self Consumption (CSC) in the European context has supported the regulation of the concept of shared energy and provided economic saving to its members. Many countries have adopted a virtual scheme for local energy sharing without a physical basis for calculating intra-community energy exchanges and national legislation often provides economic incentives for shared energy within the community. However, many of the management aspects regarding the distribution of shared energy and therefore economic gain are managed internally by members, allowing for various configurations that depending on the type of generation systems, users, and purposes of the community. Since a unique method is not established, it is crucial to define fair criteria for energy allocation among the community members rewarding virtuous behaviour. This work proposes four algorithms for dynamic sharing keys based on participants’ contributions to the community: a consumption-proportional key, a Pearson correlation coefficient-based key to evaluate synchronism between electricity drawn from the grid and the surplus fed into the grid, a trend-based key that accounts for the difference between purchased and injected energy, and a combination of the previous two keys. A Renewable Energy Community (REC), under Italian regulation, consisting of eight representative users was simulated using real hourly energy consumption and production profiles. The aim was to perform an annual comparative analysis between the developed methods and identify the different amount of shared energy assigned to each user based on their contribution, highlighting their strengths and limitations. The results show how some of the algorithms assign to users with the highest consumption an amount of shared energy higher than their real sharing potential, while users with greater sharing potential are penalised
Design and performance analysis of a High Field Side antenna for Plasma Position Reflectometry control on DTT
Get PDFThe Divertor Test Tokamak (DTT) will allow the test and validation, in reactor-like regimes, of control diagnostics relevant to DEMO operation. In DEMO, Plasma Position Reflectometry (PPR) will provide non-magnetic measurements of plasma position and shape, involving the use of several poloidally distributed lines-of-sight (LOS). A multi-LOS PPR is presently under design on DTT to gather more experimental knowledge on the operation of such systems out of the usual equatorial plane LOS. Priority has been given to planning the High-field-side (HFS) reflectometers due to their impact on the design of the first wall and vessel. To cope with the severe space and access constraints imposed to the antenna placement on the inner side of the tokamak vessel, two optimized, small-footprint, bistatic and monostatic hog-horn antenna designs are proposed. To demonstrate the viability of a PPR implementation on DTT's HFS, we present herein 3D full-wave simulations in the DTT single null plasma scenario, laboratory measurements of a 3D-printed bistatic antenna prototype, and a preliminary thermal analysis of the antenna when embedded in the plasma-facing wall structures under standard plasma operation conditions
Evidence of the Electrochemical Ca2+ Intercalation in Anatase Nanotubes
Get PDFHere, we demonstrate the electrochemical intercalation of Ca2+ ions within the lattice of anatase nanotubes (a-NTs) synthesized by hydrothermal treatment of TiO2/NaOH precursors followed by Na+/H+ ion exchange and H2O-loss at high temperature in air. Scanning electron microscopy, X-ray diffraction, and Raman spectroscopy confirm the formation of nanosized anatase, whereas transmission electron microscopy highlights the formation of nanotubular morphologies with an average diameter of 10 nm. TiO2 electrodes are able to deliver reversible specific capacities in aprotic batteries vs. calcium metal or in hybrid configurations vs. capacitive activated carbon using aprotic electrolytes (i. e., Ca(BH4)2 in tetrahydrofuran or Ca(TFSI)2 in dimethoxyethane, respectively). The electrochemical intercalation of Ca2+ ions into the anatase lattice is confirmed by X-ray absorption spectroscopy in close comparison with Na+ and Li+ intercalations. Ca2+ incorporation leads to the partial amorphization of the TiO2 lattice despite the limited Ca/Ti ratio (i. e., 0.09) obtained in discharge. The analysis of the extended X-ray absorption fine structure region allows the determination of the local structure of the incorporated Ca2+ ions and confirms that a disordered environment is obtained after the electrochemical reaction
Fiber-Optics Quench Detection Schemes in HTS Cables for Fusion Magnets
No full textIn this article, we report the results from two test campaigns conducted to evaluate the feasibility of implementing a commercially available optical fiber-based distributed sensing technology for Quench Detection (QD) purposes. We successfully characterized the temperature response and sensitivity achievable by this technique when using a bare single mode fiber within a cryogen free cooling system operating in the temperature range from 4 K to 300 K. A fiber was also incorporated into a sample featuring an High-Temperature Superconductor (HTS) stack mounted onto an extruded Aluminum slotted-core cable. Quench-like events were triggered by locally lowering the critical current using the magnetic field produced by a set of permanent magnets placed near the center of the stack. The experiments were carried out at 77 K by cooling the sample through the central channel of the Aluminum core with a forced flow of liquid nitrogen. The test results indicate the viability of this technology as a suitable alternative for QD in long-length HTS cables and motivate further work to develop distributed sensing systems able to work in the conditions foreseen for HTS fusion coils
Sensitivity of REBCO Tapes and Thin Film to γ-Irradiation
No full textSignificant interest in high-temperature superconductor (HTS) REBa2Cu3O7-δ (REBCO, RE = Y or Rare Earths) materials for space and nuclear applications is increasing in recent years, triggered by the commercial availability of REBCO tapes. In both cases, the investigation of radiation effects on such tapes is mandatory. In this work, commercial REBCO tapes from different suppliers were compared before and after 60Co gamma irradiation at 1.016 kGy absorbed dose, typical for space applications, carried out at the ENEA Calliope irradiation Facility. No significant effects on the Tc and Ic at 77 K self-field and Ic(B) at 4.2 K were observed. Similar null effects were reported for both epitaxial YBCO films on STO and LAO substrates reference samples irradiated to the same dose. This is a promising result for electronic devices and magnets operating in the environment of outer space. Gamma irradiation test at higher fusion-relevant doses will be performed in the next future
Preliminary thermal-hydraulic deterministic safety analysis of an in-vessel LOCA for the DTT facility
Get PDFThe DTT (Divertor Tokamak Test) facility is a new experimental tokamak under development by an Italian consortium in cooperation with several high-standard European laboratories. The ENEA division FSN-SICNUC is involved in the project for carrying out deterministic safety analysis of postulated accidents. In the first year of activity, it has been analyzed an In-Vessel LOCA (IVLOCA) scenario. The IVLOCA scenario selected is caused by a break in the divertor’s cassette cooling tubes with the consequent release of coolant inside the Vacuum Vessel (VV). The best estimate thermal-hydraulic system code TRACE, developed by USNRC, was selected to conduct the preliminary thermal-hydraulic analysis of this accident. DTT is currently under design, so not all the data are frozen. Therefore, based on some engineering assumptions and scaling considerations from similar facilities, the nodalization of DTT VV was developed using the three-dimensional TRACE component "VESSEL". Then, a sensitivity analysis was carried out to simulate the break and the consequent water injection in the VV. This was done to compare the system behavior and test different nodalization approaches. Subsequently, the data of the DTT divertor cooling system were used to run additional simulations. The results allow to compare different nodalization approaches and to have a preliminary estimate of the pressure peak and temperature behavior in the VV for an IVLOCA. Finally, a first uncertainty analysis was carried out using the DAKOTA toolkit, coupled with TRACE code in SNAP. Two uncertain input parameters were selected: the rupture area of a cooling divertor tube and the temperature of the divertor coolant. The uncertainty analysis allows having a wider spectrum of system behavior and a preliminary insight on the dispersion of the VV pressure, selected as figure of merit. This paper aims to show the results of this preliminary analysis, characterizing the phenomena that occurred during the selected transient
Assessment of the relevancy of ENEA Water Loop facility with respect to ITER WCLL TBS Water Cooling System by considering their thermal-hydraulic performances
Get PDFThe Water-Cooled Lead-Lithium (WCLL) is one of the two candidate concepts for the Breeding Blanket (BB) of DEMO. A Test Blanket Module (TBM) together with its Water Cooling System (WCS) is going to be installed and tested in the ITER reactor. The WCS acts as primary cooling circuit of the TBM module, and it is designed to reproduce the water thermodynamic conditions expected at the DEMO BB inlet. During last years, ENEA and the DIAEE of Sapienza University of Rome have carried out the conceptualization of the Water Loop (WL) facility, belonging to the W-HYDRA experimental platform planned at C.R. Brasimone. The W-HYDRA platform is composed by three individual facilities called: Water Loop, Steam, and LIFUS5/Mod4. Water Loop replicates the salient thermal-hydraulic features of the ITER WCLL WCS, and it is equipped with a test section placed inside a Vacuum Vessel (VV) to investigate mock-ups of the whole TBM or its individual parts. This paper assesses the relevancy of the WL facility with respect to ITER WCLL TBM System comparing their thermal-hydraulic performances during selected operational and accidental conditions. Two RELAP5/Mod3.3 models were developed, and the outcomes of the simulations showed a good agreement, thus demonstrating the effectiveness of WL facility to support the ITER TBM program
Effect of aliovalent substitution on the local structure of CaKFe4As4 superconductor
Get PDFWe have investigated the local structure of the iron-based CaKFe4As4 superconductor featuring distinct aliovalent substitutions at the Ca and K sites, that is CaKFe4As4, CaK0.9Sr0.1Fe4As4, CaK0.9Ba0.1Fe4As4 and Ca0.9Na0.1K0.9Ba0.1Fe4As4. Temperature-dependent Fe K-edge extended x-ray absorption fine structure (EXAFS) measurements are used to determine the near-neighbors bondlengths and their stiffness. The EXAFS analysis reveals that the Fe-As bondlength undergoes negligible changes by substitution, however, the Fe-Fe bondlength and the As height are affected by the Sr substitution. The superconducting transition temperatures of CaK0.9Sr0.1Fe4As4 and CaK0.9Ba0.1Fe4As4 are very similar even if the mean As heights are significantly different suggesting that the anion height may not be a unique parameter to describe the superconductivity in CaKFe4As4. The mean As heights show a peculiar temperature dependence characteristic of CaKFe4As4 system. Furthermore, the temperature-dependent mean square relative displacements reveal similar Fe-Fe bond stiffness in all samples, instead the Fe-As bond is substantially stiffer in case of CaK0.9Sr0.1Fe4As4. The local structure results are discussed in relation to the differing transport properties of aliovalent substituted 1144 superconductor
Photo-Thermal Optimization of a Parabolic Trough Collector with Arrayed Selective Coatings
Get PDFThis work aims at enhancing the photo-thermal performance of a parabolic trough collector (PTC) system by implementing multiple coatings arrayed along the receiver tube. For this purpose, a lumped-parameter model was developed in the radial direction of the receiver tube to compute absorber tube wall temperature and heat losses at various heat transfer fluid (HTF) temperatures. The HTF is a mixture of molten salt (60%wt. NaNO3 + 40%wt. KNO3). The lamped-parameter model was exploited by a 1D model developed in the axial direction to determine the HTF temperature profile along the tube. The 1D model was employed to calculate photo-thermal efficiency at different HTF temperatures considering six selective coating formulations. Consequently, the most photo-thermally efficient configuration of the PTC system was determined, encompassing three HTF temperature ranges characterized by three different selective coating formulations. These temperature ranges were 290–436 °C (low temperature), 436–517 °C (medium temperature) and 517–550 °C (high temperature). The respective tube lengths were computed to be 792 m, 566 m and 293 m, considering the reference operational conditions. The optimal configuration enhanced the overall photo-thermal efficiency by 0.5–1.9% compared to the single-coated configurations. Furthermore, receiver cost could be reduced because of the employment of the more expensive coating only at the final segment