A5033541227- Solar and Space Plasma Dynamics
- Ionosphere and magnetosphere dynamics
- Magnetic confinement fusion research
- Plasma Diagnostics and Applications
- Astro and Planetary Science
- Geomagnetism and Paleomagnetism Studies
- Fluid Dynamics and Turbulent Flows
- Earthquake Detection and Analysis
- Solar Radiation and Photovoltaics
- Dust and Plasma Wave Phenomena
- Laser-induced spectroscopy and plasma
- Computational Physics and Python Applications
- Geophysics and Gravity Measurements
- Atmospheric Ozone and Climate
- Electromagnetic Simulation and Numerical Methods
- Laser-Plasma Interactions and Diagnostics
- Oceanographic and Atmospheric Processes
- Lattice Boltzmann Simulation Studies
- Magnetic Properties and Applications
- Spacecraft Design and Technology
- Tropical and Extratropical Cyclones Research
- Particle accelerators and beam dynamics
- High-Energy Particle Collisions Research
- Meteorological Phenomena and Simulations
- Electromagnetic Scattering and Analysis
Ruhr University Bochum
2020-2024
KU Leuven
2010-2020
Jet Propulsion Laboratory
2019
University of Bergamo
2011
University of Alberta
2011
Los Alamos National Laboratory
2007
Polytechnic University of Turin
2007
Polo Universitario Città di Prato
2006
Abstract We present results of a two-dimensional fully kinetic particle-in-cell simulation in order to shed light on the role whistler waves scattering strahl electrons and heat-flux regulation solar wind. model electron velocity distribution function as initially composed core populations typically encountered near-Sun wind observed by Parker Solar Probe. demonstrate that, consequence evolution (VDF), two branches instability can be excited, which drive propagating direction oblique or...
The electrons are an essential particle species in the solar wind. They often exhibit non-equilibrium features their velocity distribution function. These include temperature anisotropies, tails (kurtosis), and reflectional asymmetries (skewness), which contribute a significant heat flux to If these sufficiently strong, they drive kinetic micro-instabilities. We develop semi-graphical framework based on equations of quasi-linear theory describe electron-driven instabilities apply our...
Aims : This paper presents a H2020 project aimed at developing an advanced space weather forecasting tool, combining the MagnetoHydroDynamic (MHD) solar wind and coronal mass ejection (CME) evolution modelling with energetic particle (SEP) transport acceleration model(s). The EUHFORIA 2.0 will address geoeffectiveness of impacts mitigation to avoid (part the) damage, including that extreme events, related eruptions, streams, SEPs, particular emphasis on its application forecast...
Abstract In situ observations of the solar wind have shown that electron velocity distribution function (VDF) consists a quasi-Maxwellian core, comprising most population, and two sparser components: halo, which are suprathermal quasi-isotropic electrons, an escaping beam strahl. Recent Parker Solar Probe (PSP) Orbiter (SO) added one more ingredient to known nonthermal features, deficit—a depletion in sunward region VDF, already predicted by exospheric models but never so extensively...
Two-dimensional particle-in-cell (PIC) simulations explore the collisionless tearing instability developing in a Harris equilibrium configuration pair (electron–positron) plasma, with no guide field, for range of parameters from non-relativistic to relativistic temperatures and drift velocities. Growth rates match predictions Zelenyi & Krasnosel'skikh ( Astron. Zh. , vol. 56, 1979, pp. 819–832) modified drifts by Hoshino Astrophys. J. 900, issue 1, 2020, p. 66) as long assumption holds...
As the solar wind expands in inner heliosphere, evolution and relaxation of electron velocity distribution function (eVDF) is governed by a complex interplay collisional collisionless processes.This study investigates with numerical simulations competition between Coulomb collisions firehose instability (EFI) - kinetic arising under anisotropic pressure conditions during isotropization VDF.The goal to gain deeper insights into how processes influence each other this regime.Fully are run...
Two-dimensional particle-in-cell (PIC) simulations explore the collisionless tearing instability from a Harris equilibrium of pair (electron-positron) plasma, with no guide field, for range parameters non-relativistic to relativistic temperatures and drift velocities. Growth rates match predictions Zelenyi & Krasnosel'skikh (1979) modified drifts by Hoshino (2020) as long assumption holds that thickness current sheet is larger than Larmor radius. Aside confirming these predictions,...
We present a systematic attempt to study magnetic null points and the associated energy conversion in kinetic Particle-in-Cell simulations of various plasma configurations. address three-dimensional performed with semi-implicit electromagnetic code iPic3D different setups: variations Harris current sheet, dipolar quadrupolar magnetospheres interacting solar wind; relaxing turbulent configuration multiple points. Spiral nulls are more likely created space plasmas: all our except lunar anomaly...
The role of solar wind expansion in generating whistler waves is investigated using the EB-iPic3D code, which models self-consistently within a fully kinetic semi-implicit approach. simulation initialized with an electron velocity distribution function modeled after Parker Solar Probe observations during its first perihelion at 0.166 au, consisting dense core and anti-sunward strahl. This initially stable respect to instabilities. Expansion drives into successive regimes where heat flux...
In-situ observations of the solar wind reveal that electron velocity distribution function (VDF) is composed a quasi-Maxwellian core, which constitutes majority population, along with two more sparse components: halo, consisting suprathermal and quasi-isotropic electrons, strahl, an escaping beam population. Recent measurements by Parker Solar Probe (PSP) Orbiter (SO) have identified additional feature in non-thermal VDF structure: deficit—a depletion sunward region VDF, long...
Discoveries by Parker Solar Probe (PSP) highlight the significance of nonthermal distributions in triggering ion-scale instabilities (Verniero et al. 2020, 2022; An 2024; Liu 2024). In this study, we show how electron (kappa) distribution could change onset threshold ion-acoustic instability (IAI) recently observed PSP (Mozer 2021, 2023; Kellogg 2024) between 15 and 25 solar radii modeled Afify (2024). We perform analytical studies kinetic simulations using Vlasov-Poisson code with a...
The process of deriving fluid equations from the Vlasov equation for collisionless plasmas involves a fundamental challenge known as closure problem. This problem consists fact that temporal evolution any particle moment—such density, current, pressure, or heat flux—includes terms depend on next higher-order moment. Consequently, truncating description at nth order necessitates approximating contributions (n+1)th moment within choice truncation level and assumptions...
In computational plasma physics kinetic models are used to simulate phenomena where small scale is expected be of importance. These contain the full information particle velocity distribution function but computationally expensive. Therefore, cheaper utilized, which can then deployed larger scales e. g. 10-moment fluid or magnetohydrodynamics (MHD). However, large behavior critically influenced by behavior. For example, solar wind observations show that ion and electron instabilities...
The long-term evolution of large domain particle-in-cell simulations collisionless magnetic reconnection is investigated following observations that show two possible outcomes for reconnection: toward a Petschek-like configuration or multiple X points. In the present simulation, mixed scenario develops. At earlier time, plasmoids are emitted, disrupting formation structures. Later, an almost stationary monster plasmoid forms, preventing emission other plasmoids. A situation reminiscent...
We study the parametric decay instability of parallel-propagating Alfvén waves in a low-beta plasma using one-dimensional fully kinetic simulations. focus for first time on conversion energy stored initial wave into particle internal energy, and its partition between species. show that compressible fluctuations generated by pump secondary ion-acoustic mode reflected contribute to gain via two distinct mechanisms. First, leads nonlinearly proton trapping phase-space mixing, agreement with...
Abstract The expanding solar wind plasma ubiquitously exhibits anisotropic nonthermal particle velocity distributions. Typically, proton distribution functions (VDFs) show the presence of a core and field-aligned beam. Novel observations made by Parker Solar Probe (PSP) in innermost heliosphere have revealed new complex features VDFs, namely beams that sometimes experience perpendicular diffusion. In this study, we use 2.5D fully kinetic simulation to investigate stability VDFs with observed...
One of the goals machine learning is to eliminate tedious and arduous repetitive work. The manual semi-automatic classification millions hours solar wind data from multiple missions can be replaced by automatic algorithms that discover, in mountains multi-dimensional data, real differences properties. In this paper we present how unsupervised clustering techniques used segregate different types wind. We propose use advanced reduction methods pre-process introduce Self-Organizing Maps...
Abstract The evolution of the electron heat flux in solar wind is regulated by interplay between several effects: expansion, which can potentially drive velocity–space instabilities, turbulence, wave–particle interactions, and, possibly, collisions. Here we address respective role played expansion and firehose instability (EFI), developing presence multiple populations, regulating flux. We carry out fully kinetic, expanding box model simulations separately analyze enthalpy, bulk, velocity...
Tokamak start-up is strongly dependent on the state of initial plasma formed during breakdown. We have investigated through numerical simulations effects that pre-filling pressure and induced electric field pure ohmic heating breakdown process. Three modes discharge are found, as a function different parameters: no mode, successful mode runaway mode. No often occurs with low or high pressure, while electrons usually easy to generate at ( ${<}1.33\times 10^{-4}$ Pa). The behaviours...
Abstract We address the challenges that come with fully kinetic Particle-In-Cell (PIC) simulations of expanding solar wind by introducing a semi-implicit, Expanding Box Model (EBM) approach to study physics. Plasma propagation and expansion are dealt via variable change EBM. In this way large separation between scales interest domain size is addressed including as time-dependent coupling terms coordinate stretching. The semi-implicit discretization, in widely used Implicit Moment Method...