Publications de Stefano Coda | EPFL Graph Search

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The impact of the finite grid size in SOLPS-ITER edge plasma simulations is assessed for JET H-mode discharges with a metal wall. For a semi-horizontal divertor configuration it is shown that the separatrix density is at least 30% higher when a narrow scra ...

Real time control of heating systems is essential to maximize plasma performance and avoid or neutralize instabilities under changing plasma conditions. Several feedback control algorithms have been developed on the Tokamak a Configuration Variable (TCV) t ...

Carbon impurity transport is studied in the TCV tokamak using a charge exchange recombination diagnostic. TCVs flexible shaping capabilities were exploited to extend previous impurity transport studies to negative triangularity (delta < 0). A practical way ...

JT-60SA is currently the world's largest superconducting tokamak. It accelerates the realization of fusion energy by supporting ITER exploitation and complementing it in addressing key physics and engineering issues for DEMO reactors. The main targets of JT-60SA are breakeven-equivalent high-temperature deuterium plasmas and high-βsteady-state plasmas. To achieve these goals, laser-aided diagnostics with high spatial resolution are essential for detailed physics studies. In Operation Phase 1, a tangential s

Simulations of the plasma current density evolution in electron internal transport barrier discharges on the Tokamak a Configuration Variable (TCV) have been performed, in order to determine the relationship between the safety-factor profile and the electr ...

The paper describes the operation and upgrade of the Heating Neutral Beam Injection (HNBI) system as well as the related infrastructure at the Tokamak Configuration Variable (TCV) during the last years. In 2023, the installation of new TCV neutron shieldin ...

Recent studies (Maggi et al 2015 Nucl. Fusion 55 113031; Maggi et al 2017 Nucl. Fusion 57 116012) have shown that on JET with the Be/W ITER-like wall (JET-ILW) in high beta discharges with high D-2 gas rates, the inter-ELM temperature pedestal growth is sa ...

In a tokamak fusion reactor the energetic alpha particles will transiently stabilize the magnetohydrodynamic activity causing sawtooth oscillations. The crash events terminating long sawtooth free periods can provide seed islands for neoclassical tearing modes [O. Sauter et al., Phys. Rev. Lett. 88, 105001 (2002)]. To shorten the sawtooth periods localized current drive near the q=1 surface is a possibility. This Letter provides the first experimental evidence for the effectiveness of this method in the dif

The TCV tokamak continues to leverage its unique shaping capabilities, flexible heating systems and modern control system to provide a stepladder approach for extrapolations of experimental results from different ma-chines to ITER and DEMO. TCV's configura ...

Runaway electrons (REs) are a concern for tokamak fusion reactors from discharge startup to termination. A sudden localized loss of a multi-megaampere RE beam can inflict severe damage to the first wall. Should a disruption occur, the existence of a RE see ...

An experimental study of the extraordinary mode (X mode) absorption at the third electron cyclotron harmonic frequency has been performed on the TCV tokamak in plasmas preheated by X mode at the second harmonic. Full single pass absorption of injected X3 power was measured with X2 preheating in co-current drive (CO-ECCD). The measured absorption exceeds that predicted by the linear ray tracing code TORAY-GA by more than a factor of 2 for the CO-ECCD case. Experimental evidence indicates that a large fractio

A power-balance model, with radiation losses from impurities and neutrals, gives a unified description of the density limit (DL) of the stellarator, the L-mode tokamak, and the reversed field pinch (RFP). The model predicts a Sudo-like scaling for the stel ...

A new modular, digital, distributed feedback control system has been developed and installed to control the TCV plasma. With many more inputs and outputs, it provides the possibility to build control algorithms using far more information on the plasma state than previously possible as well as the ability to control many more actuators, including the multi-megawatt, multi-launcher electron cyclotron heating and current drive system. This paper provides an overview of the new control system, its integration i

Improved electron energy confinement in tokamak plasmas, related to internal transport barriers, has been linked to nonmonotonic current density profiles. This is difficult to prove experimentally since usually the current profiles evolve continuously and ...

Post mortem analysis shows that mid and high atomic number metallic impurities are present in deposits on JET plasma facing components with the highest amount of Ni and W, and therefore the largest sink, being found at the top of the inner divertor. Source ...

A large superconducting machine, JT-60SA has been constructed to provide major contributions to the ITER program and DEMO design. For the success of the ITER project and fusion reactor, understanding and development of plasma controllability in ITER and DE ...

The actively cooled technology used for the plasma facing components demands monitoring and control of heat flux on ITER first wall (FW) panels. Intense heat loads are predicted on the FW, even well before the burning plasma phase. Thus, a real-time (RT) F ...

Full conversion from ohmic to runaway electron (RE) driven current was observed in the tokamak a configuration variable (TCV) following massive injection of neon through a disruption mitigation valve into a low-density limited circular plasma. Following a ...

The effects of plasma shape on confinement and sawtooth stability are studied for positive and negative discharge triangularity and for different elongations with 1.5 MW centrally deposited ECH power

Stefano Coda

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On the role of finite grid extent in SOLPS-ITER edge plasma simulations for JET H-mode discharges with metallic wall

From sawtooth to profile control: developing feedback control using ECRH/ECCD systems on the TCV tokamak

Study of impurity C transport and plasma rotation in negative triangularity on the TCV tokamak

Laser-aided diagnostics of JT-60SA

Current density evolution in electron internal transport barrier discharges in TCV

Present status of heating neutral beam injection system at TCV

Inter-ELM evolution of the edge current density in JET-ILW type I ELMy H-mode plasmas

Destabilization of fast-ion-induced long sawteeth by localized current drive in the JET tokamak

Upgrade of the neutral beam heating system on the TCV tokamak - second high energy neutral beam

Expulsion of runaway electrons using ECRH in the TCV tokamak

Full absorption of third harmonic ECH in TCV tokamak plasmas in the presence of second harmonic ECCD

A power-balance model of the density limit in fusion plasmas: application to the L-mode tokamak

Architecture and commissioning of the TCV distributed feedback control system

Inductive current density perturbations to probe electron internal transport barriers in tokamaks

Deposition of impurity metals during campaigns with the JET ITER-like Wall

Plasma physics and control studies planned in JT-60SA for ITER and DEMO operations and risk mitigation

Conditions for anomalous energy and momentum transfer from electrons to ions in ECCD discharges on TCV

Model-based real-time power flux estimator for the ITER first wall

Full conversion from ohmic to runaway electron driven current via massive gas injection in the TCV tokamak

Energy Confinement in Shaped TCV Plasmas with Electron Cyclotron Heating