Publications by Ambrogio Fasoli

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The TORoidal Plasma EXperiment (TORPEX) is a basic plasma physics device where a Simple Magnetized Torus configuration (SMT) can be obtained superimposing a small vertical magnetic field component on the main toroidal field, resulting in open magnetic helical field lines. This configuration reproduces some of the main features of a tokamak plasma edge, including density and magnetic field gradient and curvature. In the last years, a complete study of electrostatic fluctuations and turbulence has been comple

Fast ions have been observed to be accelerated in the presence of Edge Localised Modes (ELMs) and MHD activity on the Tokamak & aacute; Configuration Variable. The acceleration time, velocity-space and frequency dynamics have been resolved by analysing the fast-ion losses measured using a unique Fast Ion Loss Detector (FILD) that allows microsecond velocity-space mapping. The findings presented herein complement and extend previous studies done at the Asdex Upgrade Tokamak and show a decorrelation between t

Edge Localised Modes (ELMs) induced fast-ion losses have been characterised in the energy, E, and pitch, λ = v ∥ / v , space using a unique Fast Ion Loss Detector (FILD) on the tokamak à configuration variable. The FILD is equipped with a 128 Avalanche Pho ...

The impurity concentration in the tokamak divertor plasma is a necessary input for predictive scaling of divertor detachment, however direct measurements from existing tokamaks in different divertor plasma conditions are limited. To address this, we have a ...

The design and operation of a new vaporizing assembly used for Q-plasma sources are described in this article. The vaporizing system, consisting of two ovens and an effuser, is used to vaporize and direct atoms onto a hot ionizer plate. The hot plate, which may be of tantalum, tungsten, or rhenium, singly ionizes the atoms on contact. The main advantages of this new assembly, compared to previous designs, are the production of higher plasma densities and the control of the radial plasma profile. The heaters

Irradiations with 14 MeV fusion neutrons are planned at Joint European Torus (JET) in DT operations with the objective to validate the calculation of the activation of structural materials in functional materials expected in ITER and fusion plants. This st ...

The JET experimental campaign has focused on studies in support of the ITER physics basis. An overview of the results obtained is given for the reference ELMy H mode and advanced scenarios, which in JET are based on internal transport barriers. JET studies for ELMy H mode have been instrumental in the definition of ITER FEAT. Positive elongation and current scaling in the ITER scaling law have been confirmed, but the observed density scaling fits a two term (core and edge) model better. Significant progress

Experimentally, it is observed that Toroidal Alfven Eigenmodes (TAEs) are difficult to excite with an external antenna when the plasma is in X-point geometry. Here, the effect of the X-point geometry on the efficiency of the TAE excitation with the externa ...

This paper presents experimental results on the accessibility and the properties of plasmas with improved confinement in TCV. First, the H-mode threshold power is measured in Ohmic plasmas. Above an Ohmic threshold density, the threshold power increases with the density. A lower threshold density is found when additional electron cyclotron heating (ECH) is applied. At these low densities, the threshold power increases dramatically with decreasing density. Only a small fraction of the wide operational domain

On the Tokamak a Configuration Variable (TCV), electron internal transport barriers (eITBs) can be formed during a gradual evolution from a centrally peaked to a hollow current profile while all external actuators are held constant. The formation occurs ra ...

We present the real-time VME system used to detect and track MHD instabilities, and particularly Alfven Eigenmodes, on the JET tokamak [J.Wesson, Tokamaks, 3rd ed., Oxford Science Publication, Oxford, 2003, p.617]. This system runs on a 1 kHz clock cycle, ...

In this paper, we analyze heat transport in the JET tokamak using data from its high resolution ECE diagnostic and analyses based on the transfer entropy (TE). The analysis reveals that heat transport is not smooth and continuous, but is characterized by ' ...

The pressure gradient of the high confinement pedestal region at the edge of tokamak plasmas rapidly collapses during plasma eruptions called edge localised modes (ELMs), and then re-builds over a longer time scale before the next ELM. The physics that con ...

The TORoidal Plasma EXperiment (TORPEX) is a Simple Magnetized Torus (SMT) where open helical magnetic field lines are obtained from the superposition of a small vertical component on the main toroidal field. The SMT configuration features the main driving mechanisms of plasma instabilities characterising the Scrape-Off Layer (SOL) of larger tokamak devices, making TORPEX a very attractive machine to perform fusion oriented studies of plasma turbulence. A new experimental set-up has been recently developed

Tritium accumulation in fusion reactor materials is considered a serious radiological issue, therefore a lot of effort has been concentrated on the development of radiometric techniques. A novel method, based on gradual dissolution, for the determination o ...

The Tokamak a Configuration Variable (TCV) tokamak is equipped with high-power (4.5 MW), real-time-controllable EC systems and flexible shaping, and plays an important role in fusion research by broadening the parameter range of reactor relevant regimes, b ...

The gyrokinetic toroidal code (GTC) has been used to study toroidal Alfven eigenmodes (TAEs) in high-performance plasmas. Experiments performed at the Joint European Torus (JET), where TAEs were driven by energetic particles arising from neutral beams, ion ...

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 and the use of these medium-n AEs for diagnostic purposes is investigated experimentally using a new set of compact in-vessel antennas, providing a direct and real-time measurement of the frequency, damping rate and amplitude for each individual toroidal mode number. First, we report on the development of a new algorithm for

Alfven eigenmodes driven by energetic particles are routinely observed in tokamak plasmas. These modes consist of poloidal harmonics of shear Alfven waves coupled by inhomogeneity in the magnetic field. Further coupling is introduced by 3D inhomogeneities ...

Ambrogio Fasoli

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First results on the plasma fluctuations of the TORPEX device in the new magnetic field configurations

Dynamics of the Fast-ion Acceleration in Type-i Elmy H-mode Scenarios on the Tcv Tokamak

First measurements of velocity-space resolved intra-ELM fast-ion losses on the TCV tokamak

An assessment of nitrogen concentrations from spectroscopic measurements in the JET and ASDEX upgrade divertor

New Vaporizing Assembly for Q-Plasma Sources

Activation Inventories After Exposure To Dd/Dt Neutrons In Safety Analysis Of Nuclear Fusion Installations

Overview of JET results in support of the ITER physics basis

Modeling of TAE mode excitation with an antenna in realistic X-point geometry

Accessibility and properties of ELMy H-mode and ITB plasmas in TCV

Safety factor profile requirements for electron ITB formation in TCV

The JET Alfven Eigenmode Local Manager for the real-time detection and tracking of a frequency-degenerate spectrum of MHD instabilities

Radial variation of heat transport in L-mode JET discharges

Pedestal evolution physics in low triangularity JET tokamak discharges with ITER-like wall

Study of plasma fluctuations in new closed flux-surface configurations of the TORPEX experiment

Novel method for determination of tritium depth profiles in metallic samples

Overview of physics research on the TCV tokamak

Gyrokinetic simulations of toroidal Alfven eigenmodes excited by energetic ions and external antennas on the Joint European Torus

Recent JET Experiments on Alfven Eigenmodes with Intermediate Toroidal Mode Numbers: Measurements and Modelling

Recent JET Experiments on Alfven Eigenmodes with Intermediate Toroidal Mode Numbers: Measurements and Modelling

Modification of the Alfven wave spectrum by pellet injection