Publications by Stefano Coda | EPFL Graph Search

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The TCV tokamak has the dual mission of supporting ITER and exploring alternative paths to a fusion reactor. Its most unique tools are a 4.5 MW electron cyclotron resonance heating system with seven real-time controllable launchers and a plasma control system with 16 independent shaping coils. Recent upgrades in temperature, density and rotation diagnostics are being followed by new turbulence and suprathermal electron diagnostics, and a new digital real-time network has been commissioned. The shape control

Electromagnetic waves that resonate with the cyclotron motion of electrons in a magnetized plasma can efficiently transfer their momentum and energy to the plasma. This is routinely used to heat or drive current in tokamak plasmas. The impact of this local ...

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 ...

Electron cyclotron resonance heating (ECRH) and current drive (ECCD), disruptive events, and sawtooth activity are all known to produce suprathermal electrons in fusion devices, motivating increasingly detailed studies of the generation and dynamics of this suprathermal population. Measurements have been performed in past years in the TCV tokamak using a single pinhole hard-X-ray (HXR) camera and electron-cyclotron-emission (ECE) radiometers, leading in particular to the identification of the crucial role o

We present a model for the particle balance in the post-disruption runaway electron plateau phase of a tokamak discharge. The model is constructed with the help of, and applied to, experimental data from TCV discharges investigating the so-called 'low-Z be ...

The problem of avoiding saturation of the coil currents is critical in large tokamaks with superconducting coils like ITER. Indeed, if the current limits are reached, a loss of control of the plasma may lead to a major disruption. Therefore, a current limi ...

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 ...

The 1MW power of the neutral beam injector (NBI) enters the plasma of the Tokamak a Configuration Variable (TCV) through a duct. The original beam propagation model predicted a maximal heat flux on the internal faces of the duct below 350 kW/m(2), leading ...

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 ...

During a recent reversed toroidal field (B-T) campaign at the Joint European Torus (JET), experiments were performed to investigate the effect on sawteeth of neutral beam injection (NBI)-driven toroidal plasma rotation counter to the direction of the toroi ...

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 ...

A Doppler backscattering (DBS) diagnostic has recently been installed on the Tokamak & agrave; Configuration Variable (TCV) to facilitate the study of edge turbulence and flow shear in a versatile experimental environment. The dual channel V-band DBS syste ...

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 ...

Electron cyclotron current drive (ECCD) is an important prospective tool for tailoring the current profile in nextstep devices. To fill the remaining gaps between ECCD theory and experiment, especially in the efficiency and localization of current drive, a better understanding of the physics of suprathermal electrons appears necessary. In TCV the fast electron population is diagnosed by a multichordal, spectrometric hard x-ray camera and by a highfield side electron cyclotron emission radiometer. The main m

This paper presents the first application to real JET data of the new equilibrium code NICE which enables the consistent resolution of the inverse equilibrium reconstruction problem in the framework of non-linear free-boundary equilibrium coupled to the St ...

The sawtooth control mechanism in plasmas employing toroidally propagating ion cyclotron resonance waves is extended. The asymmetrically distributed energetic passing ions are shown to modify the ideal internal kink mode when the position of the minority i ...

Reliable algorithms for disruption avoidance and prediction are foreseen to play a fundamental role in the JET control system for the successful operation of the machine in the upcoming deuterium-tritium campaigns. The integration of such algorithms is exp ...

The electron temperature and density pedestals tend to vary in their relative radial positions, as observed in DIII-D (Beurskens et al 2011 Phys. Plasmas 18 056120) and ASDEX Upgrade (Dunne et al 2017 Plasma Phys. Control. Fusion 59 14017). This so-called ...

Experimental evidence from the JET tokamak is presented supporting the predictions of a recent theory (Graves et al 2009 Phys. Rev. Lett. 102 065005) on sawtooth instability control by toroidally propagating ion cyclotron resonance waves. Novel experimenta ...

Recently, an experimental campaign has been launched on TCV with the aim of exploring and extending the limits of the operating space. The vertical position control system has been optimized, with the help of extensive model calculations, in order to allow operation at the lowest possible stability margin. In addition, the growth rate of the axisymmetric instability has been minimized by choosing optimum values for the plasma triangularity and squareness and by operating close to the current limit imposed b

Stefano Coda

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Progress and Scientific Results in the TCV Tokamak

Electron-cyclotron resonance heating and current drive source for flux-driven gyrokinetic simulations of tokamaks

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

Suprathermal electron studies in the TCV tokamak: design of a tomographic hard-X-ray spectrometer

An upper pressure limit for low-Z benign termination of runaway electron beams in TCV

Implementation of an Iter-relevant Qp-based Current Limit Avoidance Algorithm in the Tcv Tokamak

MHD spectroscopy of JET plasmas with pellets via Alfven eigenmodes

Beam duct for the 1 MW neutral beam injector on TCV

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

Exploring a small sawtooth regime in Joint European Torus plasmas with counterinjected neutral beams

Non-Maxwellian fast particle effects in gyrokinetic GENE simulations

Survey of the Edge Radial Electric Field in L-mode Tcv Plasmas Using Doppler Backscattering

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

Electron cyclotron current drive and suprathermal electron dynamics in the TCV tokamak

Equilibrium reconstruction at JET using Stokes model for polarimetry

A new sawtooth control mechanism relying on toroidally propagating ion cyclotron resonance frequency waves: Theory and Joint European Torus tokamak experimental evidence

A First Analysis of JET Plasma Profile-Based Indicators for Disruption Prediction and Avoidance

Effect of the relative shift between the electron density and temperature pedestal position on the pedestal stability in JET-ILW and comparison with JET-C

Experimental verification of sawtooth control by energetic particles in ion cyclotron resonance heated JET tokamak plasmas

Extension of the TCV operating space towards higher elongation and higher normalized current