Modelling Innovative High Temperature Superconductors for Fusion Applications

L'abstract è presente nell'allegato / the abstract is in the attachmen

Validation of the 4C Code on the AC Loss Tests of a Full-Scale ITER Coil

The AC loss tests on the first ITER Central Solenoid Module (CSM) have been modelled and compared to the test results. The model has been implemented in the 4C code, a thermal-hydraulic modelling tool which includes the CSM winding pack and the cryogenic circuit of the test facility. Two modes of operation of the circuit have been analyzed: the nominal and the “isolation” mode, i.e., when the cryogenic circuit valves are operated to isolate the coil during the current dumps. The computed mass flow rate, pressure and coil outlet temperature at different locations have been compared with the measurements, showing a very good agreement in both modes of operation of the circuit. The validated model helped in the interpretation of the experimental results, such as the backflow at the coil inlet -which cannot be measured- or the non-monotonic outlet temperature evolution following the current dump. Furthermore, the code was used to qualify the isochoric method for the quantification of the deposited energy due to AC losses, as it was the only method applicable in case of current dumps from high current

CFD analysis of natural convection cooling of the in-vessel components during a shutdown of the EU DEMO fusion reactor

In view of the large neutron fluence expected in a fusion power plant, the maintenance of the in-vessel components (IVC) must be carried out using Remote Handling (RH); however, before the RH robots can intervene, the temperature of the IVCs must be reduced, so a cooldown phase is required after the reactor shutdown before maintenance activities can start. In the EU DEMO two options are being investigated to cool down the Breeding Blanket (BB) structures before maintenance, namely introducing fans to pump air in forced convection in the plasma chamber (after opening the Vacuum Vessel), or letting the air at room temperature cool down the structures by natural convection; if the required downtime is acceptable, the second option is clearly preferred, as it would reduce the cost and complexity of the system. This work analyses the natural convection option via a 3D transient Computational Fluid-Dynamics (CFD) conjugate heat transfer model, to evaluate the required time to cool down the BB

A Transient 3-D CFD Model for the Simulation of Forced or Natural Convection of the EU DEMO In-Vessel Components

As the EU DEMO reactor will act as a Component Test Facility for the breeding blanket (BB), it is foreseen that the different BB concepts will be tested throughout the plant’s lifetime. The maintenance of all the in-vessel components (IVCs), as for all D-T fusion machines, must be carried out employing remote handling (RH) technology, as the structural materials will be activated by the neutrons. The maintained segment and possibly other nearby segments cannot be actively cooled and will heat up due to the decay heat. For these reasons, alternative cooling strategies need thus to be investigated to ensure that the BB segment will cool down within the limits required by the RH in a reasonable amount of time. In the present work, two possible cooling options are investigated for the case of the Water-Cooled Lithium-Lead BB concept. One is based on the passive cool-down by natural convection of the BB segments, whereas the second one relies on a forcing flow of cool air on the BB surfaces. A computational fluid dynamics (CFD) approach has been used to study the different options for performing transient analyses through the Star-CCM+ commercial code

Design, Test and Analysis of a Gyrotron Cavity Mock-Up Cooled Using Mini Channels

In 2016, we have designed, built and finally tested at the FE200 facility in Le Creusot (France) a planar mock-up mimicking the water-cooled cylindrical resonance cavity of the European 170 GHz, 1 MW gyrotron to be used for electron cyclotron plasma heating in ITER. The aim of the mock-up is the characterization of the cooling capability of the cavity. A Glidcop® target is heated with an electron beam gun with resulting peak heat fluxes relevant for the full-size cavity. Underneath the target surface, whose temperature is monitored by means of a pyrometer, a set of parallel semi-circular mini-channels, with diameter of 1.5 mm, allows the flow of pressurized water, entering the mockup at ~ 9 bar and 40 °C. Several thermocouples measure the target temperature, at different distances from the heated target surface. The experimental results show that the mock-up is capable to withstand a heat fluxes of 21 MW/m2, while the cooling system keeps the heated surface below ~ 400 °C, for flow conditions comparable to those of the full-size cavity. The test results are used to first calibrate the uncertain model parameters and then, with frozen parameters, to validate a previously developed CFD model, showing good agreement with the experiment. In view of its reliability, this model might eventually be a useful tool for the simulation of the full-size gyrotron cavity operation

Commissioning and improvements of the instrumentation and launch of the scientific exploitation of OARPAF, the Regional Astronomical Observatory of the Antola Park

The OARPAF telescope is an 80-cm-diameter optical telescope installed in the Antola Mount Regional Reserve, in Northern Italy. We present the results of the characterization of the site, as well as developments and interventions that have been implemented, with the goal of exploiting the facility for scientific and educational purposes. During the characterization of the site, an average background brightness of 22.40mAB (B filter) to 21.14mAB (I) per arcsecond squared, and a 1.5″ to 3.0″ seeing, have been measured. An estimate of the magnitude zero points for photometry is also reported. The material under commissioning includes three CCD detectors for which we provide the linearity range, gain, and dark current; a 31-orders échelle spectrograph with R ∼ 8500 to 15,000 and a dispersion of n = 1.39 × 10 − 6 px − 1λ + 1.45 × 10 − 4 nm / px, where λ is expressed in nm. The scientific and outreach potential of the facility is proven in different science cases, such as exoplanetary transits and active galactic nuclei variability. The determination of time delays of gravitationally lensed quasars, the microlensing phenomenon, and the tracking and the study of asteroids are also discussed as prospective science cases

CFD analysis of natural convection cooling of the in-vessel components during a shutdown of the EU DEMO fusion reactor (dataset)

Simulation file for the publication "CFD analysis of natural convection cooling of the in-vessel components during a shutdown of the EU DEMO fusion reactor" published in Fusion Engineering and Design. Work carried out within the framework of the EUROfusion Consortium. Needs Simcenter STAR-CCM+ v2019.3 to be viewed

Asset tracking architecture with Bluetooth Low Energy tags and ad hoc smartphone applications

The paper describes an original architecture aimed at tracking assets within construction sites or similar contexts. The main components are: i) RFID tags, ii) Bluetooth Low Energy (BLE) tags and iii) smartphones. The core functions of the architecture are performed by two Android applications: the Asset Proximity Locator (APL) and the Wandering Objects Location Finder (WOLF). The key feature of the asset tracking function is the ability to maximize smartphone battery lifetime by switching on and off the GPS unit, thus guaranteeing that the smartphone can be used for an entire working shift. A detailed energy consumption analysis is carried out for each component of the architecture. The results achieved by simulations, concerning BLE tag detection probability, are presented and discussed