Publications de Ambrogio Fasoli

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Magnetic reconnection in collisionless magnetohydrodynamic plasmas is studied under controlled conditions in toroidal X-line configurations formed in the center of the Versatile Toroidal Facility [J. Egedal , Rev. Sci. Instrum. 71, 3351 (2000)]. Profiles of key parameters are measured during driven reconnection pulses in the reproducible plasma discharges. The experimental results prove to be highly sensitive to the boundary conditions applied. In the configuration with "open" boundaries reconnection is fas

Gradient driven electrostatic instabilities are investigated in TORPEX [A. Fasoli, B. Labit, M. McGrath, S. H. Muller, M. Podesta, and F. M. Poli, Bull. Am. Phys. Soc. 48, 119 (2003)], a toroidal device (R=1 m, a=0.2 m) in which plasmas are produced by mic ...

Neutron emission spectroscopy is a diagnostic technique that allows for energy measurements of neutrons born in nuclear reactions. The JET tokamak fusion experiment (Culham, UK) has a special role in this respect as advanced spectrometers for 2.5 MeV and 1 ...

Bayesian integrated data analysis combines measurements from different diagnostics to jointly measure plasma parameters of interest such as temperatures, densities, and drift velocities. Integrated data analysis of fast-ion measurements has long been hampe ...

This paper presents results of extensive analysis of mode excitation observed during the operation of the Alfven Eigenmode Active Diagnostic (AEAD) in the JET tokamak during the 2019-2020 deuterium campaign. Six of eight toroidally spaced antennas, each wi ...

Scientific and technical activities on JET focus on the issues likely to affect the ITER design and operation. Our understanding of the ITER reference mode of operation, the ELMy H-mode, has progressed significantly. The extrapolation of ELM size to ITER has been re-evaluated. Neoclassical tearing modes have been shown to be meta-stable in JET, and their beta limits can be raised by destabilization (modification) of sawteeth by ion cyclotron radio frequency heating (ICRH). Alpha simulation experiments with

We have investigated the effect of different ion cyclotron resonance frequency (ICRF) heating schemes, of error field modes, of the plasma shape and edge magnetic shear, and of the ion delB drift direction on the stability of Alfven eigenmodes (AEs). The use of multi-frequency or 2nd harmonic minority ICRF heating at high plasma density gives rise to a lower fast ion pressure gradient in the plasma core and to a reduced mode activity in the Alfven frequency range. Externally excited low-amplitude error fiel

Electrostatic turbulence, related structures and their effect on particle, heat and toroidal momentum transport are investigated in TORPEX simple magnetized plasmas using high-resolution diagnostics, control parameters, linear fluid models and nonlinear nu ...

Experiments are conducted on the JET tokamak to demonstrate the diagnostic potential of Magneto-Hydro-Dynamics (MHD) spectroscopy, for the plasma bulk and its suprathennal components, using Alfven eigenmodes (AEs) excited by external antennas and by energetic particles. The measurements of AE frequencies and mode numbers give information on the bulk plasma. Improved equilibrium reconstruction, in particular in. terms of radial profiles of density and safety factor, is possible from the comparison between th

Alfven eigenmodes and other magnetohydrodynamic phenomena have been studied in tokamak plasmas at the Joint European Torus (JET) using a new eight-channel, 4 s, 1 MHz, 12-bit data acquisition system (KC1F) in conjunction with the JET fast Mirnov magnetic fluctuation pickup coils. To this end, the JET magnetic pickup coils were calibrated in the range 30-460 kHz using a new remote calibration technique which accounts for the presence of the first few LRC circuit resonances. Signal processing software has bee

A unique parabolic relation is observed to link skewness and kurtosis of around ten thousand density fluctuation signals, measured over the whole cross section of a toroidal magnetized plasma for a broad range of experimental conditions. All the probabilit ...

Negative triangularity plasma configurations have been extensively studied in the Tokamak à Configuration Variable (TCV), and have displayed enhanced heat confinement for thermal electrons and ions. Herein, the question of fast-ion confinement is addressed. Limited negative (NT) and positive triangularity (PT) plasmas are compared. The plasma volume and position are kept the same between the discharges to match the neutral beam heating (NBI) deposition, isolating the effect of triangularity. These plasmas w

This paper presents the transport analysis of high density baseline discharges in the 2016 experimental campaign of the Joint European Torus with the ITER-Like Wall (JET-ILW), where a significant increase in the deuterium-deuterium (D-D) fusion neutron rat ...

A pedestal prediction model Europed is built on the existing EPED1 model by coupling it with core transport simulation using a Bohm-gyroBohm transport model to self-consistently predict JET-ILW power scan for hybrid plasmas that display weaker power degrad ...

Owing to its detailed diagnostics, feasibility of parameter scans, and relatively simple configuration, the basic plasma physics experiment TORPEX is an ideal testbed in which to perform experiment/simulation comparisons and to contribute to the establishment of the validation methodology. Focusing on observables related to Langmuir probe measurements, we consider a number of physical quantities that can be used as observables for experiment/simulation comparison. We classify the observables according to a

A new definition of the sheath edge is rigorously derived taking into account the kinetic properties of the plasma, and a consistent set of local sheath edge conditions is presented for the case of a magnetic field perpendicular to the wall. These local boundary conditions give explicit expressions for the ion velocity, the electron velocity, and the electron heat flux at the sheath edge, which can be easily implemented in a fluid code. It is shown that in the case of positive current to the wall, the commo

The measurement of the energy spectra and densities of alpha-particles and other fast ions are part of the ITER measurement requirements, highlighting the importance of energy-resolved energetic-particle measurements for the mission of ITER. However, it ha ...

The TAE antenna system on JET is used to drive intermediate and high n Alfvén Eigenmodes (AEs) into the plasma so as to study their properties and estimate their stability by measuring their damping rates as a function of the various plasma parameters. In order to bring the system to full and optimized operation in terms of driving higher current into the antennas and hence higher magnetic perturbations into the plasma, the design of a matching unit was considered. The latter required a complete and accurat

The EUROfusion Work Package JET3 programme, established to enable the technological exploitation of the JET experiments over the next years, includes, within the NEXP subproject, a novel Shutdown Dose Rate (SDR) experiment. Considering its ITER-relevance, ...

Operation of the JET tokamak with beryllium and tungsten ITER-like wall provides unique opportunity for detailed studies on dust generation: quantity, morphology, location, etc. The programme carried out in response to ITER needs for safety assessment comp ...

Ambrogio Fasoli

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Experimental evidence of fast reconnection via trapped electron motion

Electrostatic turbulence and transport in a simple magnetized plasma

Neutron emission spectroscopy of D plasmas at JET with a compact liquid scintillating neutron spectrometer

Bayesian Integrated Data Analysis of Fast-Ion Measurements by Velocity-Space Tomography

Results from the Alfven Eigenmode Active Diagnostic during the 2019-2020 JET deuterium campaign

Overview of JET results

Alfven mode stability and wave-particle interaction in the JET tokamak: prospects for scenario development and control schemes in burning plasma experiments

Electrostatic instabilities, turbulence and fast ion interactions in the TORPEX device

MHD spectroscopy

Fast magnetic fluctuation diagnostics for Alfven eigenmode and magnetohydrodynamics studies at the Joint European Torus

Universal statistical properties of drift-interchange turbulence in TORPEX plasmas

Fast ion confinement in negative triangularity plasmas on the TCV tokamak

High fusion performance at high T-i/T-e in JET-ILW baseline plasmas with high NBI heating power and low gas puffing

Integrated modelling of H-mode pedestal and confinement in JET-ILW

The validation project on the TORPEX basic plasma physics experiment

Sheath boundary conditions for plasma fluid models

Diagnostic of fast-ion energy spectra and densities in magnetized plasmas

Electrical model of the Alfvén eigenmode exciter on JET

Shutdown dose rate measurements after the 2016 Deuterium-Deuterium campaign at JET

Dust generation in tokamaks: Overview of beryllium and tungsten dust characterisation in JET with the ITER-like wall