A5017501979- Magnetic confinement fusion research
- Atomic and Molecular Physics
- Particle accelerators and beam dynamics
- Plasma Diagnostics and Applications
- Solar and Space Plasma Dynamics
- Ionosphere and magnetosphere dynamics
- Dust and Plasma Wave Phenomena
- Laser-Plasma Interactions and Diagnostics
- Laser-induced spectroscopy and plasma
- Particle Accelerators and Free-Electron Lasers
- Cold Atom Physics and Bose-Einstein Condensates
- Fluid Dynamics and Turbulent Flows
- Superconducting Materials and Applications
- Muon and positron interactions and applications
- Gyrotron and Vacuum Electronics Research
- Mass Spectrometry Techniques and Applications
- Astrophysics and Star Formation Studies
- Geomagnetism and Paleomagnetism Studies
- Electron and X-Ray Spectroscopy Techniques
- Stellar, planetary, and galactic studies
- Quantum chaos and dynamical systems
- Atomic and Subatomic Physics Research
- Advanced Data Storage Technologies
- Physics of Superconductivity and Magnetism
- Gas Dynamics and Kinetic Theory
Istituto Nazionale di Fisica Nucleare, Sezione di Milano
2015-2024
University of Milan
2015-2024
Istituto Nazionale di Fisica Nucleare, Sezione di Pavia
2022-2024
University of Brescia
2022-2024
Institute of Plasma Physics
1993-2021
Max Planck Institute for Plasma Physics
1996-2020
IRCCS Ospedale San Raffaele
2019
Istituto Nazionale di Fisica Nucleare
2007-2016
California Institute of Technology
2010
University of Calabria
2010
The neoclassical prediction of the “electron root,” i.e., a strongly positive radial electric field, Er (being solution ambipolarity condition particle fluxes), is analyzed for low-density discharges in Wendelstein-7-AS [G. Grieger, W. Lotz, P. Merkel, et al., Phys. Fluids B 4, 2081 (1992)]. In these electron cyclotron resonance heated (ECRH) with highly localized central power deposition, peaked Te profiles [with Te(0) up to 6 keV and Ti≪Te] region are measured. It shown that this root”...
Two linear trap devices for particle beam manipulation (including emittance reduction, cooling, control of instabilities, dust dynamics, and non-neutral plasmas) are here presented, namely, a radiofrequency quadrupole (RFQ) cooler compact Penning with injector. Both dynamics studies by means dedicated codes including the interaction ions buffer gas (up to 3 Pa pressure), electromagnetic design RFQ reported. The multipurpose is aimed study multispecies charged samples, primarily electron...
ECRH driven transport of suprathermal electrons is studied in non-axisymmetric plasmas using a new Monte Carlo simulation technique 5-D phase space. Two different phases the can be seen. The first rapid convective due to direct radial motion trapped and second slower collisional transport. important role broadening deposition profile W7-AS clarified. flux also evaluated considered relation `electron root' feature recently observed W7-AS. It found that, at low collisionalities, play dominant...
Kinetic effects are important in low-density high-power ECRH discharges, and the electron distribution function can significantly deviate from Maxwellian. The power deposition is analysed for perpendicular on-axis heating W7-AS, with different magnetic configurations characterized by either a minimum or maximum of B on plasma axis RF injection plane. scenarios modelled means new bounce-averaged Fokker - Planck code, well suited field geometry close to W7-AS.
The authors compare thin layers of nanochannels and plain foils as targets for ultraintense laser driven proton acceleration, showing a more intense flux protons with higher energy nanochannels.
Electron cyclotron resonance heating and electron current drive (ECCD) in the W7-X stellarator, which is presently under construction, are investigated by means of a ray-tracing code. Two schemes considered: launching extraordinary ordinary waves from low magnetic field side at second harmonic frequency.
Abstract In this paper we report the measurement of laser-driven proton acceleration obtained by irradiating nanotube array targets with ultrashort laser pulses at an intensity in excess 10 20 W cm −2 . The energetic spectra forward accelerated protons show a larger flux and higher cutoff energy if compared to flat foils comparable thickness. Particle-In-Cell 2D simulations reveal that packed favour better laser-plasma coupling produce efficient generation fast electrons moving through...
Abstract The plasmoid formation in collisionless plasmas, where magnetic reconnection within turbulence may take place driven by the electron inertia, is analyzed. We find a complex situation which, due to presence of strong velocity shears, typical formation, observed influence energy cascade magnetohydrodynamic context, has coexist with Kelvin–Helmholtz (KH) instability. that current density layers undergo or KH instability depending on local values and fields. competition among these...
The ELTRAP device installed at the Department of Physics University Milan is a Malmberg–Penning trap, with magnetic field up to 0.2 T, equipped charge coupled optical diagnostics. It intended be small scale facility for electron plasma and beam dynamics experiments, in particular study collective effects, equilibrium states, formation coherent structures these systems. features relatively long solenoid, corrected by 4 shims 16 dipole coils, order obtain large uniform region. modular...
An investigation of the ions induced diocotron instability in an electron plasma confined a Malmberg–Penning trap is presented. The detection based on spectral analysis charge signals walls confining electrodes, which allows tracking displacement from axis. dependence energy analysed by three different methods: (i) injecting electrons with energies, (ii) heating single radio frequency burst, (iii) varying ramp-up time voltage. experimental technique to limit ion resonance instability,...
High power electron cyclotron current drive (ECCD) experiments in the W7-AS stellarator are analysed. In these net-current-free discharges, ECCD and bootstrap feedback controlled by an inductive current. Based on measured density temperature profiles, neoclassical predictions of (with ambipolar radial electric field taken into account) densities as well from linear adjoint approach with trapped particles included calculated. For stationary conditions, balance is checked. Launch-angle scans...
Plasma generation is observed in a cylindrical Penning–Malmberg trap the ultra-high vacuum pressure regime for large bandwidth of low-power radio frequency (RF) excitations. The process plasma formation investigated by measuring density profiles and simplified model developed to characterize electron heating mechanism. total charge confined at equilibrium systematically studied RF drives 0.1–20 MHz range with different geometrical configurations. With densities some 106 cm−3 least, scheme...
The application of a radio-frequency (RF) excitation to any electrode Penning-Malmberg trap may result in significant electron heating and ionization the residual gas with formation plasma column when RF frequency is order or larger than typical axial bounce frequencies few-eV electrons. use quadrupolar can induce additional phenomena, like dense, narrow-cross section columns which exhibit an mθ=1 diocotron mode, i.e., rotation their center around axis. A series experiments presented...
The injection phase in a Malmberg-Penning trap is investigated both experimentally the ELTRAP [M. Amoretti et al., Rev. Sci. Instrum. 74, 3991 (2003)] device, and numerically. resulting plasma density distribution studied by varying source parameters, external magnetic field strength, axial position of potential barrier. Space charge phenomena dominate dynamics system; formation hollow columns three-dimensional structures are observed. processes interpreted using particle-in-cell code which...
When the cold nonrelativistic guiding center approximation is valid, transverse dynamics of highly magnetized electron plasma columns confined in Penning-Malmberg traps analogous to that an incompressible, inviscid, two-dimensional (2D) fluid whose vorticity corresponds, up a constant proportionality, axially averaged density. In this work intermittency phenomena freely decaying 2D turbulence are investigated through scaling properties probability density functions and flatness spatial...
A novel method was experimentally demonstrated to produce a low-density electron plasma in Penning–Malmberg trap, exploiting the static electric and magnetic confinement fields together with periodic excitation amplitudes as low 0.5–5 V frequencies MHz range. This unusual technique proved be applicable replacement for conventional sources Penning devices presents interesting aspects both terms of basic science technological applications. Nevertheless, experimental observations demonstrate...
The two-dimensional (2-D) merging of an intense, pointlike vortex with a diffuse, extended is investigated experiments using strongly magnetized electron columns in Malmberg–Penning trap, and numerical simulations 2-D particle-in-cell code. study restricted to highly nonlinear conditions, where the perturbative approach does not apply. A very good agreement between experiment simulation obtained. wraps about itself, moving toward center system during process. interaction generates filaments...