In plasmas and in astrophysical systems, particle diffusion faster than normal, namely superdiffusion, has been detected, calling for a generalisation of Fick’s law and of the transport equation. Formally, superdiffusive transport is often described by fractional diffusion equations, where the second-order spatial derivative is changed into a spatial derivative of fractional order less than...
This study leverages a fully compressible 3D Hall-MHD numerical simulation of space plasma turbulence to explore multiscale coupling between streamlines and magnetic field line topologies, turbulent cascade rate, and energy dissipation. Through gradient tensor geometric invariants, we investigate the interplay between large-scale fluid dynamics and small-scale dissipative phenomena. From an...
Coronal mass ejections (CME)-driven shocks are the most efficient accelerators of gradual solar energetic particles (SEPs), which pose risks to technological infrastructure and human activity in space. Knowing the physical properties of expanding shocks is critical in order to prevent SEPs hazard and to understand their impact to the near-Earth environment. However, a thorough picture on how...
The photosphere-corona system is governed by magnetohydrodynamic (MHD) processes spanning multiple scales. Photospheric plasma turbulent convection continuously reconfigures magnetic field topology, while coronal plasma dynamics respond to the underlying magnetic boundary conditions. This plasma-magnetic coupling produces coronal holes (CHs)—regions where coronal plasma flows freely along open...
Understanding the dynamics of small-scale magnetic fields in the solar
photosphere is essential for interpreting the physical processes
occurring in the upper layers of the solar atmosphere, where magnetic
coupling drives chromospheric and coronal activity. In this work we
present an improved simulation framework designed to investigate the
statistical properties of magnetic-loop...
Operare piattaforme satellitari in un’orbita terrestre molto bassa (Very Low Earth Orbit - VLEO), a un’altitudine inferiore ai 400 km, offrirebbe vantaggi significativi sia in termini di prestazioni del carico utile sia di mitigazione dei detriti spaziali [1]. Tuttavia, la resistenza aerodinamica presente a queste altitudini, dovuta all’atmosfera residua, deve essere compensata continuamente...
Understanding plasma turbulence in curved spacetime — especially near compact objects — remains an open challenge. Conventional analyses rely on flat-spacetime techniques that cannot fully capture the effects of strong gravitational curvature. In this work, we review a recent method for studying turbulence in generic manifolds and arbitrary gravitational fields, enabling the calculation of...
Simulations of relativistic plasmas traditionally focus on the dynamics of two-species mixtures of charged particles under the influence of external magnetic fields and those generated by particle currents. However, the extreme conditions of astrophysical plasmas near compact objects, such as black holes and neutron stars, are often characterized by mixtures of electrons, protons, and...
Knowing the chemical composition of samples is essential to science and beyond, so much so that chemical analysis facilities are widespread within government agencies, universities, and industry. One of the enduring needs within the scientific community has been a capability for in situ chemical analysis for routine use outside the traditional analytical laboratory. Such instrumentation must...
Plasma turbulence is an inherently multi-scale phenomenon that spans a vast range of spatial and temporal scales. In the solar wind, the inertial-range turbulent cascade extends over nearly four decades in length (from injection scales down to ion characteristic scales), and six decades when including electron characteristic scales. Being able to self-consistently simulate such a dynamics is...
The theoretical and numerical modelling of fundamental kinetic processes in low collision plasmas is the oldest and most traditional research activity that the plasma theory team in Nancy began in the ‘60s, and which in the ‘80s led to the development of the first Eulerian and semi-Lagrangian Vlasov codes.
I will present a few of the recent research activities and results, carried out along...
Since the early studies of extragalactic jets (collimated flows of relativistic plasmas), a central question has persisted: how far can such jets propagate in space? The discovery of the 4.1 mega-parsec (Mpc) jet in the radio galaxy 3C-236 in 1974 set the benchmark for decades, later surpassed by J1420-0545 (radio galaxy with a jet extending to 4.69 Mpc) discovered in 2008. For a long time,...
Abstract:
Over the last decades, electric propulsion (EP) technologies have been playing a crucial role in the space market due to their ability to achieve higher specific impulse compared to chemical thrusters, resulting in improved propellant mass economy [1]. Although many EP thrusters are now highly mature, their lifetime is limited by plasma-induced erosion of critical components, such...
Young supernova remnants are ideal sites for studying the acceleration and transport of high-energy particles. This work presents a comprehensive investigation of particle acceleration in Cassiopeia A using spatially resolved X-ray observations, and explores how the surrounding circumstellar medium affects the acceleration efficiency. Radial intensity profiles of bright nonthermal X-ray...
A novel 2D-2V time-splitting Vlasov-Poisson solver has been used to deduce the kinetic behavior of the propagation of high-frequency electrostatic plasma waves in an inhomogeneous electron background. More specifically, we have simulated, in a scenario of constant proton density, the effect of density holes, where a lack of electrons leads to an unbalanced charge. These regions have been...
To enhance the surface properties of austenitic stainless steels widely used in biomedical applications, and to improve their wear resistance, a novel low-temperature plasma-assisted carburizing treatment was developed and optimized by tuning the methane concentration and the treatment time. Compared with the untreated material, the surface hardness increased by approximately 1.4 times, while...
Ionized Physical Vapour Deposition (iPVD) is a key plasma-based technology used across several sectors, from semiconductor manufacturing to protective coatings and energy applications [1]. Among iPVD methods, High Power Impulse Magnetron Sputtering (HiPIMS) is particularly attractive due to the peculiar plasma conditions it generates, enabling dense, adherent and finely structured coatings...
A robust and reliable vacuum degradation detection system is essential to identify leaks in the cryostat of superconducting tokamaks [1]. This Vacuum Monitoring System (VMS) must be able to function in the harsh environment encountered near superconducting magnets, while also measuring vacuum pressure as low as 2E-8 mbar, with a response time in the order of few seconds [2]. Commercial vacuum...
The study of the statistics of gradient tensors’ invariants is useful to characterize the morphological and topological features of magnetic flux and plasma streamlines in turbulent space plasmas. In the recent past some studies of the statistics of the gradient tensors’ invariants have been performed to investigate the velocity and magnetic field flow lines topologies in turbulent...
The study of astrophysical plasma in relativistic jets provides a unique laboratory for exploring high-energy particle acceleration and radiative processes. We investigate the multi-wavelength variability of blazar 3C 454.3, one of the most active extragalactic AGNs, monitored by the AGILE and Fermi satellites since 2007. In leptonic jet-emission scenarios, the optical emission arises from...
Turbulence and energy dissipation in space plasmas remain major open
questions, especially in weakly collisional environments such as the Earth’s magnetosheath. While turbulence is known to cascade energy across scales, the mechanisms by which this energy is concentrated into localized dissipation are still not well understood. One theory suggests that turbulence drives energy dissipation...
Geomagnetic field reversal sequences exhibit inter-reversal, or persistence, times spanning a broad range, from a few 10⁴ years to superchrons lasting more than 10⁷ years. Statistical analyses show that the reversal sequence does not follow a simple Poisson process with a constant rate and displays signatures of memory, clustering, and heavy-tailed behaviour. Short persistence times display...
Questo lavoro studia la ionizzazione dei propellenti atmosferici in plasmi accoppiati induttivamente (ICP). Nasce dall’interesse di approfondire la comprensione della chimica del plasma atmosferico per l’applicazione a sistemi di propulsione elettrica air-breathing (ABEP) per satelliti operanti in orbite terrestri molto basse (VLEO). Queste orbite, che vanno da 100 a 350 km di altitudine,...
One of the first important observations made by NASA’s Parker Solar Probe spacecraft (launched 2018) is the omnipresence in the inner heliosphere of sudden deflections of the magnetic field, called switchbacks. The ubiquity of these large amplitude folds was a startling result, questioning our understanding of basic magnetized plasma dynamics. Not surprisingly, these structures have attracted...
The problem of particle acceleration at interplanetary (IP) shocks is long-standing, since several unresolved issues are still debated, pushing the research on this field
to jointly explore spacecraft in-situ observations, numerical simulations, and analytical models.
In this work, we analyze several shock crossings by spacecraft in the interplanetary space in order to link the shock and...
Supernovae explosions (SNe) are among the most energetic events in
the Universe. They represent an instantaneous release of energy of about 10$^{51}$ erg, associated to the catastrophic collapse of a massive star or to a runaway nuclear burning on the surface of a white dwarf. Following the explosion, the ejected material expands into the interstellar medium (ISM), forming a Supernova Remnant...
Turbulence in plasmas involves a complex cross-scale coupling of fields and distortions of particle velocity distributions, with the generation of non-thermal features. How the energy contained in the large-scale fluctuations cascades all the way down to the kinetic scales, and how such turbulence interacts with particles, remains one of the major unsolved problems in plasma physics. Moreover,...
