Publications de Ambrogio Fasoli

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The unique flexibility of TCV in plasma shaping has been exploited to address different aspects of tokamak physics in which the plasma shape may play a role. This paper summarizes the experiments undertaken in the TCV tokamak ("Tokamak à Configuration Variable") over the last decade in stability and transport and offers a comprehensive and integrated view of the various effects of plasma shape observed. For each of these effects, the relation between experimental results and theoretical predictions is stres

Electron cyclotron resonance heating (ECRH) is a mature technology that has progressed constantly over a period of forty years, particularly as a tool in magnetic confinement fusion. As with other heating methods, this technique has seen a steady increase ...

We develop a model to investigate the time evolution of the mean location and variance of a random walker subject to Poisson-distributed collisions at constant rate. The collisions are instantaneous velocity changes where a new value of velocity is generat ...

We have designed and installed a new Langmuir-probe (LP) array diagnostic to determine basic three-dimensional (3D) features of plasmas in TORPEX. The diagnostic consists of two identical LP arrays, placed on opposite sides of the apparatus, which provide ...

Fast particle driven instabilities are investigated at low toroidal field B-0 approximate to 1 T in tritium, deuterium and hydrogen plasmas. Tritium, deuterium and hydrogen neutral beams with energies of 160, 140 and 110 keV were injected, respectively, into tritium, deuterium and hydrogen plasmas. The destabilization of Alfven eigenmodes was observed during injection of tritium beams into a tritium plasma and during the injection of deuterium beams into a deuterium plasma but not during the injection of hy

A new compact gamma-ray spectrometer was developed in order to optimise the measurement of bremsstrahlung radiation emitted from runaway electrons in the MeV range. The detector is based on a cerium doped lutetium-yttrium oxyorthosilicate (LYSO:Ce) scintil ...

Blob control by creating convective cells using biased electrodes is demonstrated in simple magnetized toroidal plasmas. A two-dimensional array of electrodes is installed on a metal limiter to obtain different biasing schemes. Detailed two-dimensional mea ...

A pair of toroidally localized in-vessel antennas in Alcator C-Mod were used to excite and detect stable toroidal Alfven eigenmode (TAE) resonances in the frequency range of 400-500 kHz. By ramping the toroidal field, the plasma TAE frequency was swept through the constant antenna excitation frequency to find a resonance and the width of the resonance was measured to determine the effective damping rate of the mode. The toroidal field and density at the resonances were observed to scale as B-T proportional

Alfven eigenmodes (AEs) are routinely seen in present-day tokamaks and stellarators with energetic particles and they represent an attractive form of MHD spectroscopy that provides valuable information on background plasma and on the energetic particles. P ...

Relying on the good agreement observed between the gyrokinetic PENN model and the low toroidal mode number n damping measurements from JET, the stability of Alfven eigenmodes (AEs) is predicted for reactor relevant conditions. Full non-local wave-particle power transfers are computed between global wavefields and alpha particles in an ITER reference equilibrium, showing that low-n eigenmodes (n similar or equal to 2) are strongly damped and intermediate-n eigenmodes (n similar or equal to 12) with a global

The first experimental observation of a radio frequency (rf) wave-induced particle pinch of trapped ions has been made in experiments at the Joint European Torus with nearly on-axis high power toroidally asymmetric ICRF (ion cyclotron range of frequencies) heating. Significant differences have been detected in discharges when waves have been directed in opposite toroidal directions. In particular, fast-ion-driven Alfvén eigenmode activity, sawtooth behavior, and proton distribution functions have been found

Alfven eigenmodes (AEs) with intermediate toroidal mode numbers are modelled using the global gyrokinetic PENN code to determine the stability of high performance tokamak discharges in the presence of energetic particles. A large plasma pressure and a weak magnetic shear in the core give rise to radially extended kinetic AEs, which are stabilized by the high shear at the edge of a divertor (X point) configuration. Large values for the safety factor and the ion Larmor radius in reversed shear operation may h

The International Tokamak Physics Activity (ITPA) has developed a comprehensive overview of the results of its coordinated R&D activities in fusion physics and diagnostics implemented during the past two decades with the aim of developing an improved physi ...

The kinetic code for plasma periphery (KIPP) was used to assess the importance of the kinetic effects of parallel electron transport in the scrape-off layer (SOL) and divertor of JET high radiative H-mode inter-ELM plasma conditions with the ITER-like wall ...

This paper reports the results of recent experiments performed on the JET tokamak on Alfven eigenmodes (AEs) with toroidal mode number (n) in the range n=3—15. The stability properties of these medium-n AEs are investigated experimentally using a new set o ...

Fast ions have recently been found to significantly impact and partially suppress plasma turbulence both in experimental and numerical studies in a number of scenarios. Understanding the underlying physics and identifying the range of their beneficial effe ...

The paper is dedicated to the characterisation of multi-strap ICRH antenna coupling to plasma. Relevance of traditional concept of coupling resistance to antennas with mutually coupled straps is revised and the importance of antenna port excitation consist ...

Dynamical chaos is produced by the interaction between plasma particles and two electrostatic waves. Experiments performed in a linear magnetized plasma and a ID particle-in-cell simulation agree qualitatively: above a threshold wave amplitude, ion stochastic diffusion and heating occur on a fast time scale. Self-consistency appears to limit the extent of the heating process.

We study experimentally the effect of linear plasma density gradients on the self-modulation of a 400 GeV proton bunch. Results show that a positive or negative gradient increases or decreases the number of microbunches and the relative charge per microbun ...

The mechanism for blob generation is detailed in the toroidal magnetized plasma of the TORPEX device [ Fasoli et al., Phys. Plasmas 13, 055902 (2006) ] using an experimental configuration, which features a plasma region dominated by a coherent wave and a r ...

Ambrogio Fasoli

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Physics Insight and Performance Benefit from Plasma Shaping Experiments in MHD and Energy Transport in the TCV Tokamak

The effect of ECRH on the electron velocity distribution function

Particle transport at arbitrary timescales with Poisson-distributed collisions

Dual Langmuir-probe array for 3D plasma studies in TORPEX

Beam driven Alfven eigenmodes and fishbones in JET

Development of a new compact gamma-ray spectrometer optimised for runaway electron measurements

Convective cells and blob control in a simple magnetized plasma

Initial active MHD spectroscopy experiments exciting stable Alfven eigenmodes in Alcator C-Mod

MHD spectroscopy of JET plasmas with pellets via Alfven eigenmodes

Global Alfven eigenmode stability in thermonuclear tokamak plasmas

Evidence for a wave induced particle pinch in the presence of toroidally asymmetric ICRF waves

Stability of Alfven eigenmodes in optimized tokamaks

Introduction and Overview: Chapter 1 of the Special Issue: on the Path to Tokamak Burning Plasma Operation

Assessment of the strength of kinetic effects of parallel electron transport in the SOL and divertor of JET high radiative H-mode plasmas using EDGE2D-EIRENE and KIPP codes

Recent JET Experiments on Alfvén Eigenmodes with Intermediate Toroidal Mode Numbers: Measurements and Modelling with the TAEFL code

Non-Maxwellian fast particle effects in gyrokinetic GENE simulations

ICRH antenna &ITS&IT-matrix measurements and plasma coupling characterisation at JET

Stochastic Plasma-Heating by Electrostatic-Waves - a Comparison between a Particle-in-Cell Simulation and a Laboratory Experiment

Proton Bunch Self-Modulation in Plasma with Density Gradient

Mechanism for blob generation in the TORPEX toroidal plasma