Publications associées à Nappe de courant

Exploration of the parameter space for the excitation and saturation of Edge Harmonic Oscillations

This thesis presents advancements in the understanding of the plasma conditions leading to the excitation and saturation of the Edge Harmonic Oscillations (EHOs) observed during QH-mode operation in tokamak plasmas. Such operations represent a safer altern ...

EPFL2023

Numerical study of delta-function current sheets arising from resonant magnetic perturbations

Joaquim Loizu Cisquella, Yao Zhou

General three-dimensional toroidal ideal magnetohydrodynamic equilibria with a continuum of nested flux surfaces are susceptible to forming singular current sheets when resonant perturbations are applied. The presence of singular current sheets indicates t ...

2022

Rapid optimization of stationary tokamak plasmas in RAPTOR: demonstration for the ITER hybrid scenario with neural network surrogate transport model QLKNN

Olivier Sauter, Federico Alberto Alfredo Felici, Michele Marin, Simon Van Mulders

This work presents a fast and robust method for optimizing the stationary radial distribution of temperature, density and parallel current density in a tokamak plasma and its application to first-principle-based modeling of the ITER hybrid scenario. A new ...

IOP Publishing Ltd2021

Potential of Radio Telescopes as High-Frequency Gravitational Wave Detectors

Valerie Fiona Domcke

In the presence of magnetic fields, gravitational waves are converted into photons and vice versa. We demonstrate that this conversion leads to a distortion of the cosmic microwave background (CMB), which can serve as a detector for MHz to GHz gravitationa ...

2021

Poloidal asymmetry in the narrow heat flux feature in the TCV scrape-off layer

Basil Duval, Christian Gabriel Theiler, Stefano Coda, Ivo Furno, Paolo Ricci, Holger Reimerdes, Benoît Labit, Joaquim Loizu Cisquella, Jan Horacek, Federico Nespoli, Federico David Halpern, Cedric Kar-Wai Tsui

Heat flux profiles inferred from a reciprocating probe at the outer midplane of the TCV tokamak during inner wall limited discharges feature radial fall-off lengths that shorten near the last closed flux surface (LCFS) consistent with the so-called narrow ...

American Institute of Physics (AIP)2017

High-beta, steady-state hybrid scenario on DIII-D

Holger Reimerdes

The potential of the hybrid scenario (first developed as an advanced inductive scenario for high fluence) as a regime for high-beta, steady-state plasmas is demonstrated on the DIII-D tokamak. These experiments show that the beneficial characteristics of h ...

IOP Publishing Ltd2016

The Science Program of the TCV Tokamak: Exploring Fusion Reactor and Power Plant Concepts

Stefano Coda

TCV is acquiring a new 1 MW neutral beam and 2 MW additional third-harmonic electron cyclotron resonance heating (ECRH) to expand its operational range. Its existing shaping and ECRH launching versatility was amply exploited in an eclectic 2013 campaign. A ...

IOP Publishing Ltd2015

Tokamak coordinate conventions: COCOS

Olivier Sauter

Dealing with electromagnetic fields, in particular current and related magnetic fields, yields "natural" physical vector relations in 3-D. However, when it comes to choosing local coordinate systems, the "usual" right-handed systems are not necessarily the ...

Elsevier Science Bv2013

Magnetohydrodynamic helical structures in nominally axisymmetric low-shear tokamak plasmas

Olivier Sauter, Jonathan Graves, Wilfred Anthony Cooper, Holger Reimerdes, Antoine Pochelon, Federico David Halpern, Daniele Brunetti

The primary goal of hybrid scenarios in tokamaks is to enable high performance operation with large plasma currents whilst avoiding MHD instabilities. However, if a local minimum in the safety factor is allowed to approach unity, the energy required to ove ...

Iop Publishing Ltd2013

Real-time physics-model-based simulation of the current density profile in tokamak plasmas

Olivier Sauter, Basil Duval, Stefano Coda, Timothy Goodman, Jean-Marc Moret, Federico Alberto Alfredo Felici, James Paley

A new paradigm is presented to reconstruct the plasma current density profile in a tokamak in real-time. The traditional method of basing the reconstruction on real-time diagnostics combined with a real-time Grad-Shafranov solver suffers from the difficult ...

IOP Publishing Ltd2011

Blob current structures in TORPEX plasmas: experimental measurements and numerical simulations

Ambrogio Fasoli, Ivo Furno, Paolo Ricci, Christian Gabriel Theiler, Nicola Vianello, Davoud Iraji, Diane Virginie Marie Lançon

In the simple magnetized torus TORPEX, field-aligned blobs originate from ideal interchange waves and propagate radially outward due to del B and curvature induced drifts. Time-resolved two-dimensional measurements of the field-aligned current density J(pa ...

2011

Magnetic Reconnection Triggering Magnetohydrodynamic Instabilities during a Sawtooth Crash in a Tokamak Plasma

Wilfred Anthony Cooper, Jonathan Graves

Thomson scattering measurements with subcentimeter spatial resolution have been made during a sawtooth crash in a Mega Ampere Spherical Tokamak fusion plasma. The unparalleled resolution of the temperature profile has shed new light on the mechanisms that ...

APS2010

Lower hybrid assisted plasma current ramp-up in ITER

Jonathan Bryan Lister, Sun Hee Kim

Lower hybrid (LH) assisted plasma current ramp-up in ITER is demonstrated using a free-boundary full tokamak discharge simulator which combines the DINA-CH and CRONOS codes. LH applied from the initial phase of the plasma current ramp-up increases the safe ...

2009

Current density evolution in electron internal transport barrier discharges in TCV

Olivier Sauter, Stefano Coda, Timothy Goodman, Emiliano Fable, Costanza Zucca

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 ...

2009

Gyrokinetic particle-in-cell global simulations of ion-temperature-gradient and collisionless-trapped-electron-mode turbulence in tokamaks

Sébastien Jolliet

The goal of thermonuclear fusion research is to provide power plants, that will be able to produce one gigawatt of electricity. Among the different ways to achieve fusion, the tokamak, based on magnetic confinement, is the most promising one. A gas is heat ...

EPFL2009

Study of the solar anisotropy of cosmic ray primaries of about 200 GeV energy with the L3+C muon detector

Aurelio Bay, Qian Wang, Horst Vogel, Eduardo Sanchez, Zhirui Xu, Werner Lustermann, Liang Sun, Jian Zhao, Yu Lei, Ji Hyun Kim, Zheng Wang, Matthias Weber, Xiao Wang, Yifei Guo, Xuan Yang

Context. Primary cosmic rays experience multiple deflections in the non-uniform galactic and heliospheric magnetic fields which may generate anisotropies. Aims. A study of anisotropies in the energy range between 100 and 500 GeV is performed. This energy r ...

2008

Analytical Solution for Rotor Eddy-Current Losses in a Slotless Permanent-Magnet Motor: The Case of Current Sheet Excitation

Yves Perriard, Miroslav Markovic

We present an analytical solution for the magnetic field, induced eddy currents, and the corresponding losses generated in the rotor of a slotless permanent-magnet (PM) motor. The field excitation is a current sheet placed at the stator interior surface. T ...

Institute of Electrical and Electronics Engineers2008

Current profile tailoring using localized electron cyclotron heating in highly elongated TCV plasmas

Olivier Sauter, Stefano Coda, Timothy Goodman, Stefano Alberti, Patrick Blanchard, Laurie Porte, Antoine Pochelon, Yann Camenen, Andrea Scarabosio, Gilles Arnoux

Radially localized electron cyclotron heating (ECH) at the 2nd harmonic (X2) is used to tailor the current profile through the modification of the temperature, and hence conductivity, profiles. The optimal conditions for current profile broadening are inve ...

IOP Publishing Ltd2007

Recent electron cyclotron emission results on TCV

Olivier Sauter, Basil Duval, Stefano Coda, Timothy Goodman, Patrick Blanchard, Laurie Porte, Xavier Llobet, Christian Schlatter, Henri Weisen, Emiliano Fable, Philippe Marmillod, Pierre-François Isoz, Igor Klimanov

Electron cyclotron emission (ECE) diagnostics on Tokamak a Configuration Variable (TCV) allow study of the electron temperature evolution in time with good spatial and temporal resolution at the high field side and low field side at various lines of sight. ...

2007

Sawtooth behaviour in highly elongated TCV plasmas

Olivier Sauter, Ivo Furno, Holger Reimerdes, Antoine Pochelon, Andrei Martynov

The effect of plasma elongation kappa on the sawtooth behaviour is studied in ohmically heated TCV plasmas up to values of kappa = 2.8. Above a certain value of kappa, which varies from 2.2 to 2.6 and depends on the current profile, the sawtooth oscillatio ...

2006