FAST: A European ITER satellite experiment in the view of DEMO

Fusion Advanced Studies Torus (FAST) aims to contribute to the exploitation of ITER and to explore innovative DEMO technology. FAST has been designed to study, in an integrated scenario: (a) relevant plasma-wall interaction problems, with a large power load (P/R ～ 22 MW/m; P/R² ～ 12 MW/m²) and with a full metallic wall; (b) to tackle operational problems in regimes with relevant fusion parameters; (c) to investigate the non-linear dynamics of fast particles (alpha like) in burning plasmas. FAST will operate on a wide parameters range, namely in high performance H-mode (BT ～ 8.5 T; IP ～ 8 MA) as well as in advanced Tokamak operation up to full non-inductive current scenario (IP ～ 2 MA). The main heating is based on 30 MW ICRH, but the ports have been designed to allocate up to 20 MW of 1 MeV NNBI. Helium gas at 30 K is used for cooling of the full machine, a preliminary analysis shows the possibility of realizing FAST with a complete superconductor set of coils. An innovative active system is under development to reduce and to control the magnetic ripple. Tungsten (W) or liquid lithium (L–Li) has been chosen for the divertor material plates and the code EDGE2D has been used to optimize the divertor geometry.     

Inductive heating on a NbTi CICC magnet: energy calibration and stability analysis

An experiment on a NbTi coiled cable-in-conduit conductor has been carried out, aimed at measuring its stability under the disturbance conditions determined by the discharge of a capacitor bank on pulsed coils, which produces rapidly varying fields, uniformly distributed over the conductor length. The energy amount actually deposited on the superconducting strands during the external field variations has been determined, on the basis of an experimental analysis of the AC losses and the results of a semi-empirical model of AC losses in saturation regime. The heating power has been taken as input for the simulation code Gandalf: a good agreement has been found between the simulated and the measured evolution of temperature along the conductor length during the inductive disturbance. Transient stability has been measured, as function of electromagnetic and thermo-hydraulic variables. A satisfactory agreement has been obtained in the stability diagrams between experimental data and the results of numerical simulations.     

Application of solvent dye in the field of biodiesel preservation

In this study, biodiesel (OSRB) from degummed oilseed radish oil (OSR) was obtained by transesterification, and the effect on its thermal stability of a binary compound containing a conventional antioxidant and a solvent dye was evaluated. A combination of the traditional antioxidant tert-butylhydroquinone (TBHQ) and a solvent dye, so-called CI Solvent Blue 35 (SB-35), was prepared and incorporated into OSR and OSRB prior to analysis. The acid value, peroxide value, and induction period were measured, and it was found that TBHQ and SB-35 were highly effective in stabilising OSR and OSRB when used in combination. The TBHQ/SB-35 blend had strong antioxidation activity, even at very low concentrations, when compared with the addition of the individual compounds. In summary, the results showed that a TBHQ/SB-35 blend may be successfully used as an alternative additive for improving oil and biodiesel preservation.     

Mathematical modelling of the evolution of protein distribution within single PLGA microspheres: prediction of local concentration profiles and release kinetics

Protein release from poly(D,L-lactide-co-glycolide) (PLGA) microspheres in an aqueous environment is governed by the diffusion of the protein through an autocatalytically degrading polymeric matrix. Many attempts have been made to model the release rate of proteins from biodegrading matrices, but the transport parameters involved in the process are not fully established at the microscale level. The aim of this work was to develop a new mathematical model taking into account the temporal evolution of the radial protein distribution during release, and to provide physical insight into the relation between local transport features and microsphere degradation. The model was validated by comparing its predictions with the experimentally determined protein concentration profiles in PLGA microspheres loaded with tetramethylrhodamine-labelled bovine serum albumin (BSA-Rhod) as a model protein. Morphological studies were carried out by scanning electron microscopy (SEM), while release kinetics and time-dependent BSA-Rhod concentration profiles within the microspheres were studied by a confocal laser scanning microscopy (CLSM)-assisted technique. The model, based on a modification of Fick's second law of diffusion, could closely fit the experimental protein radial distribution profiles in the microspheres as a function of time. It is also a useful tool to ab initio design protein release devices using degrading matrices.     

The key role of twist pitch and mechanical pre-treatment in the transport properties of Nb3Sn wires subject to bending strain

In modelling the transport properties of multi-filamentary Nb₃Sn strands, the knowledge of the geometrical parameters of the superconducting filaments and the electrical and mechanical properties of the different materials composing the wire are required. In particular, the filament twist pitch and the transverse resistivity between filaments have a crucial role in the definition of the current transfer length and, consequently, in the simulation of the transport performances of superconducting wires subject to mechanical loads, as in cable-in-conduit conductors (CICC) for fusion magnets during operation. We have measured the critical current and the n-index of internal tin Nb₃Sn wires with different values of the filament twist pitch, having inserted the strand into a stainless steel jacket and under the application of pure bending strain. Results show that the degradation of the transport properties is affected by the twist pitch value and, in the limit case of non-twisted filaments, even an improvement is observed in presence of bending. Moreover, the reversibility of critical current after relaxing the mechanical load has also been checked and an improvement of the performances has been observed after pre-bending applications, presumably due to the strain relaxation. In addition, the differential analysis through the second derivative of the V–I curve evidenced a peaked critical current distribution for the UNTW-strands, while TW-strands under bending showed a higher degree of non-homogeneity, proven by broader distributions.