Publications by Stefano Coda | EPFL Graph Search

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A set of experiments was carried out in JET ILW (Joint European Torus with ITER-Like Wall) L-mode plasmas in order to study the effects of light impurities on core ion thermal transport. N was puffed into some discharges and its profile was measured by act ...

TCV experiments and novel theoretical studies have addressed key questions regarding the operational space of negative triangularity (NT) plasmas in view of an L-mode NT reactor, in terms of stability, performance properties and core-edge integration. We show that reducing the top triangularity (δtop) to more negative values induces an H-L back transition, confirming the direct dependence between H-mode existence and access to 2nd ballooning stability region. We also show that the X-point δ can prohibit H-m

Starting from a standard single null X-point configuration, a second order null divertor (snowflake (SF)) has been successfully created on the Tokamak à Configuration Variable (TCV) tokamak. The magnetic properties of this innovative configuration have bee ...

Real time control of the plasma elongation and plasma current using electron cyclotron resonance heating (ECRH) actuators has been demonstrated on TCV. Tokamak plasmas may be elongated by off-axis ECRH. The associated flattening of the current density prof ...

Electron heat transport experiments are performed in L-mode discharges at various plasma triangularities, using radially localized electron cyclotron heating to vary independently both the electron temperature T-e and the normalized electron temperature gr ...

As modern fusion experiments continue to push the boundaries of fusion science, the number, complexity, and importance of standard diagnostics have increased. Ensuring the recording of high-quality data from standard diagnostics is a task of great importance, entrusted to Ph.D. students in the TCV tokamak. Students participate in the control room team as the ‘diagnostician of the day’ or diagnosticien du jour (DdJ). This paper presents recent improvements to the DdJ software routines that prepare standard d

Real-time plasma control systems are at the heart of operation of modern tokamaks. The control system of the TCV tokamak has recently seen a major upgrade in terms of its hardware and software components. Control algorithms are entirely programmed and test ...

Measurements of electron cyclotron emission (ECE) from the high field side of the TCV tokamak have been made on plasmas heated by second and third harmonic X-mode electron cyclotron heating (ECH) and electron cyclotron current drive (ECCD). Suprathermal ECE, up to a factor of six in excess of thermal emission, is detected in the presence of second harmonic X-mode (X2) ECCD and of third harmonic X-mode (X3) ECH. The measured ECE spectra are modelled using a bi-Maxwellian describing the bulk and the suprather

This contribution reports on the study of suprathermal electron radial transport enhancement in the presence of electron-heating radio-frequency waves, such as electron-cyclotron waves or lower-hybrid waves. Since suprathermal electrons emit hard X-rays from Bremsstrahlung, experimental data from hard X-ray measurements are used to follow their dynamics. In particular, electron-cyclotron power modulation experiments performed in TCV show that this transport depends on the total electron-cyclotron power. The

The ASDEX Upgrade (AUG) programme, jointly run with the EUROfusion MST1 task force, continues to significantly enhance the physics base of ITER and DEMO. Here, the full tungsten wall is a key asset for extrapolating to future devices. The high overall heat ...

A first set of divertor gas baffles has recently been installed in the TCV tokamak. In order to explore the physics determining the benefits and limitations of divertor baffling and to guide the design of a possible second generation of baffles, the effect ...

The First Mirror Test for ITER has been carried out in JET with mirrors exposed during: (i) the third ILW campaign (ILW-3, 2015-2016, 23.33 h plasma) and (ii) all three campaigns, i.e. ILW-1 to ILW-3: 2011-2016, 63,52 h in total. All mirrors from main cham ...

In a previous paper, a Self-Organizing Map had proven to be able to identify the regions of the plasma operative space characterizing the pre-disruptive phase at JET without relying on any a priori information. One of the strengths of this disruption predictor lies in its inherent self-organization capability. The Self-Organizing Map discovers non-trivial relationships and captures the complicated interplay of device diagnostics on the internal plasma states directly from the experimental data. Moreover, th

Important advances have been made recently in the invention and application of experimental methods to control the sawtooth instability in tokamak plasmas. The primary means of control involves the application of either ion cyclotron resonance heating (ICR ...

JT-60SA is the world’s largest superconducting tokamak in operation jointly built and exploited by Europe and Japan in the framework of the Broader Approach. JT-60SA aims at addressing some of the technological and physics challenges, such as the long pulse steady-state plasma operation at high beta. The start-up of JT-60SA, which culminated in the first JT-60SA plasma achieved on 23 October 2023 and Operation-1 (OP-1) until the end of 2023, including the achievement of >1 MA diverted plasmas, paves the way

Within the 9th European Framework programme, since 2021 EUROfusion is operating five tokamaks under the auspices of a single Task Force called ‘Tokamak Exploitation’. The goal is to benefit from the complementary capabilities of each machine in a coordinat ...

Particle transport in tokamak plasmas has been intensively studied in the past, particularly in relation to density peaking and the presence of anomalous inward particle convection in L-and H-modes. While in the L-mode case the presence of the anomalous in ...

A large CdTe-based tomographic system has been installed two years ago on the TORE SUPRA tokamak, for a detailed investigation of the dynamics of fast electrons generated by radio-frequency waves in Fusion plasmas, as a function of time, space and energy. With 59 chords and 8 energy channels per line-of-sight, this diagnostic is the largest in the fusion community dedicated to hard X-ray studies emitted by the plasma between 20 and 200 keV. A description of the tomography as well as its performance in the a

Tokamak plasmas operating at high performance are limited by several MHD instabilities. The sawtooth instability limits the core plasma pressure and can drive the neoclassical tearing mode unstable, but also prevents accumulation of impurities in the core. ...

The impact of plasma shaping on electron heat transport is investigated in TCV L-mode plasmas. The study is motivated by the observation of an increase in the energy confinement time with decreasing plasma triangularity which may not be explained by a chan ...

Stefano Coda

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Effects of nitrogen seeding on core ion thermal transport in JET ILW L-mode plasmas

Negative Triangularity Tokamak Operation in TCV

Snowflake Divertor Plasmas on TCV

Real time control of the plasma current and elongation in tokamaks using ECRH actuators

Electron heat transport in shaped TCV L-mode plasmas

Improvements to standard diagnostic preparation and data-quality monitoring in the TCV tokamak

Overview of the TCV digital real-time plasma control system and its applications

High field side measurements of non-thermal electron cyclotron emission on TCV plasmas with ECH and ECCD

Suprathermal electron transport studies in radio-frequency-heated tokamak plasmas

Overview of physics studies on ASDEX Upgrade

Numerical investigation of optimal divertor gas baffle closure on TCV

First mirror test in JET for ITER: Complete overview after three ILW campaigns

A procedure for rule extraction from a Self-Organising plasma disruption predictor for JET

Recent Advances in Sawtooth Control

Overview of first JT-60SA plasma operation and plans in view of ITER and DEMO

Overview of the EUROfusion Tokamak Exploitation programme in support of ITER and DEMO

Observation of enhanced ion particle transport in mixed H/D isotope plasmas on JET

Hard X-ray CdTe tomography of tokamak fusion plasmas

Real time control of the sawtooth period using EC launchers

Impact of plasma triangularity and collisionality on electron heat transport in TCV L-mode plasmas