Francesco Sciortino

This project aimed at studying plasma microturbulence suppression in nuclear fusion scenarios where the confinement quality is strongly increased by the formation of a transport barrier. The Tangential Phase Contrast Imaging (TPCI) diagnostic allowed an analysis of discharges in the TCV tokamak, both in H-mode and electron Internal Transport Barrier (eITB) regimes. Using data from the Charge Exchange Recombination Spectroscopy system, we were able to calculate the radial electric field, ExB… Show more

This project aimed at studying plasma microturbulence suppression in nuclear fusion scenarios where the confinement quality is strongly increased by the formation of a transport barrier. The Tangential Phase Contrast Imaging (TPCI) diagnostic allowed an analysis of discharges in the TCV tokamak, both in H-mode and electron Internal Transport Barrier (eITB) regimes. Using data from the Charge Exchange Recombination Spectroscopy system, we were able to calculate the radial electric field, ExB drift and ExB shearing rates, which could then be used to study Doppler shifts and evaluate the Hahm-Burrell criterion in a selection of scenarios.

A new technique was presented to improve the localisation of TPCI data and the discrimination of poloidal fluctuations from radial ones. This method relies on the estimation of Doppler shifts along the positions in the plasma that are crossed by the TPCI laser beam. An investigation of microturbulence in L- and H-modes allowed the description of an unexpected inversion in turbulence poloidal propagation which can be connected to a transition from a TEM to an ITG-dominated regime. Such effect is observed to take place on short time-scales and cannot be explained based on our knowledge of edge transport barriers. Using data obtained from regions close to the plasma edge, we were also able to evaluate the Hahm-Burrell criterion for TCV H-modes and confirm the role of ExB shearing in reducing anomalous transport. An analysis of the variations of fluctuations at the formation of eITBs was made, demonstrating their localised suppression and their dependence on heating parameters. We characterised typical turbulent scenarios both in terms of a counter-propagating waves model and using a statistical approach based on normalised conditional spectra. Show less

This project aimed at producing a critical review on inductive power transfer methods. In particular, applications in thin-film polymer based coils were explored in order to release longitudinally implanted intra-fascicular electrodes from any external connections. The project summarized theoretical achievements regarding strongly-coupled devices and planar microcoils characterization, describing past research work and patents. Network analysis methods and Couple Mode Theory approaches were… Show more

This project aimed at producing a critical review on inductive power transfer methods. In particular, applications in thin-film polymer based coils were explored in order to release longitudinally implanted intra-fascicular electrodes from any external connections. The project summarized theoretical achievements regarding strongly-coupled devices and planar microcoils characterization, describing past research work and patents. Network analysis methods and Couple Mode Theory approaches were considered, also to include Debye relaxation heating processes. Selected simulations using SPICE software and Finite Element Analysis in COMSOL MultiPhysics were also adopted, in order to eventually suggest possible coil fabrication improvements. Show less

Optical spectrum calculations were computed to predict the reflectance, transmittance and absorbance due to multilayer dielectric slabs. A transfer matrix method was derived from the definition of transmission and propagation matrices for light going through an interface and across a dielectric. The effect of adding non-interacting graphene layers at single, double and multiple interfaces was analyzed and compared to the case in which non-conductive boundaries are considered.

Analysis and testing of the design of a 5th order 1 dB ripple high pass Chebyshev type I filter. A transfer function was obtained using Maxwell's method for loop currents and plotting the results over a frequency domain using a Python program. The changes in closed loop gain and phase were also found with an LTspice IV simulation, which confirmed the analytically derived curves. The circuit was then experimentally tested in laboratory and data collected over the same frequency range.

This investigation aimed at finding ways of maximizing heat exchanges between refrigeration fluids and freeze-drying chambers. Combinations of different stainless steel plates, heat transfer cements and refrigerant flow rates are analyzed and an optimal solution is experimentally researched.