Group Activities
Radiation environment and damage simulations
Radiation damage is a challenge for several HTS applications, fusion above all. To provide the lifetime expected for a component it is necessary to evaluate its radiation environment, understand the damage it causes on the crystal lattice and how this affects the functional properties. This understanding can also provide guidance in mitigation strategies.
We are specialized in characterizing the radiation environment of applications and experiments through 3D CAD-based Monte Carlo simulations performed on HPC.
The radiation damage on the material can be evaluated through atomistic simulations, we perform and combine Molecular Dynamics and Binary Collision Approximation to achieve results regardless of the energy imparted to the Primary Knock-on Atom, allowing the simulation of damage in the whole energy range of interest for fusion applications.
Molecular Dynamics simulations are only as good as the interatomic potential employed. To have full control and go toward a quantitative and validated prediction of damage, we develop and test in-house Machine Learning Interatomic Potentials.
Irradiation experiments
We have a large experience in designing and performing irradiation experiments on superconductors, focusing on the controlled modification of structure and properties to investigate damage, optimize the material and develop devices.
We perform ion irradiation experiments at several INFN facilities, where we also have dedicated beamlines. We routinely work with protons and light ions in the MeV energy range, and with heavy atoms in the 100 MeV to GeV energy range, allowing the controlled introduction of defects with different morphologies from pointlike to columnar tracks. Cryogenic irradiation is also available, with in-situ and in-operando characterization possible.
Neutron irradiation experiments are performed in collaboration with ENEA, at the FNG facility, where we are developing irradiation environments both at room and cryogenic temperatures.
We are also used to perform especially designed experiments at external facilities, to expand the possible range of irradiation and characterization on the samples of interest
Magnetic visualization
Magnetic visualization of the superconducting state allows for an immediate evaluation of the quality of samples and the quantitative investigation of vortex pinning and dynamics, before and after irradiation.
We have developed a unique facility for the Magneto Optical Imaging with an indicator Film that allows to extract quantitative maps of magnetic field and current and their dynamics to study relaxation and instabilities. Flat samples large up to a few cm can be investigated from 4 K to room temperature, in magnetic fields up to 0.2 T, with a spatial resolution of 400 nm.
HTS magnet technology
The realization of HTS magnet currently presents several critical challenges: we are developing innovations on quench detection adopting different winding approaches.
We perform multi-physics characterization of REBCO tapes under relevant magnetic field, temperature and stress conditions, and integrate the resulting material laws directly into our magnet design and quench-protection models.
Finite-element simulations of the thermal, electromagnetic, and mechanical behavior of HTS tapes, windings, and coils are used to design and optimize HTS magnets and their stability, based on experimentally measured tape properties.
Vortex matter and pinning
Investigating vortex matter and the pinning landscape of materials is interesting from a fundamental perspective, and necessary for all high field applications. We couple experimental investigation with the Magneto Optical Imaging technique with computational and theoretical analysis.
Time-dependent Ginzburg–Landau theory enables the study and visualization of vortex dynamics and their rearrangement, including in the presence of defects that act as pinning centers. We use tools that enable simulations at different spatial scales and in both 2D and 3D, with the possibility of including thermal effects through coupling to the Fourier heat equation.
Theoretical descriptions of vortex dynamics and pinning provide a framework to compare with numerical simulations, interpret experimental observations, and formulate models connecting the microstructure of artificial pinning centers and radiation damage to superconducting properties.
