Publications associées à Stellar corona

Impact of microwave beam scattering by density fluctuations on the electron-cyclotron power deposition profile in tokamaks

Stefano Coda, Joan Decker, Oleg Krutkin, Umesh Kumar, Jean Arthur Cazabonne

Electron-cyclotron waves are a tool commonly used in tokamaks, in particular to drive current. Their ability to drive current in a very localized manner renders them an optimal tool for MHD mode mitigation. However, such applications require high accuracy ...

IOP Publishing Ltd2024

Shedding light on the MRI-driven dynamo in a stratified shearing box

Abhijit Bhausaheb Bendre

We study the magneto-rotational instability (MRI) dynamo in a geometrically thin disc (H/R < 1) using stratified zero net (vertical) flux shearing box simulations. We find that mean fields and electromotive forces (EMFs) oscillate with a primary frequency ...

2024

Nonlinear interaction of Alfvénic instabilities and turbulence via the modification of the equilibrium profiles

Laurent Villard, Alberto Bottino, Xiao Wang

Nonlinear simulations of Alfvén modes (AMs) driven by energetic particles (EPs) in the presence of turbulence are performed with the gyrokinetic particle-in-cell code ORB5. The AMs carry a heat flux, and consequently they nonlinearly modify the plasma temp ...

Cambridge University Press2023

Gyrokinetic simulation of low-n Alfvenic modes in tokamak HL-2A plasmas

Javier García Hernández, Samuele Mazzi

The turbulence characteristics of plasmas with internal transport barriers in the HL-2A tokamak are analyzed by means of linear gyrokinetic simulations. It is found that turbulence is dominated by the ion temperature gradient (ITG) mode together with large ...

2023

Excitation of toroidal Alfvén eigenmodes with counter-current NBI in the TCV tokamak

Laurie Porte, Matteo Vallar, Alexander Karpushov, Samuele Mazzi

In TCV, unstable modes excited by resonant interaction between the shear Alfvèn waves in con- tinuum gaps and energetic particles have been observed in scenarios with Neutral Beam Injection (NBI). TCV is a middle-size device (R 0 /a = 0.88/0.25) equipped w ...

IOP Publishing Ltd2023

Nonlinear interactions of ion acoustic waves explored using fast imaging decompositions

Fast camera imaging is used to study ion acoustic waves propagating azimuthally in a magnetized plasma column. The high-speed image sequences are analyzed using proper orthogonal decomposition and 2D Fourier transform, allowing to evaluate the assets and d ...

2023

Present design of the Steering Mirror Assembly (SMA) for ITER ECHUL

Timothy Goodman, René Chavan, Anastasia Xydou

In the ITER Tokamak, four Electron Cyclotron Heating Upper Launchers (ECHUL) are needed to control plasma instabilities at the rational surfaces, most importantly the q = 3/2 and q = 2/1 neoclassical tearing modes (NTMs). Each ECHUL is equipped with a set ...

2023

How accurate are flux-tube (local) gyrokinetic codes in modeling energetic particle effects on core turbulence?

Olivier Sauter, Alberto Bottino, Emanuele Poli

Flux-tube (local) gyrokinetic codes are widely used to simulate drift-wave turbulence in magnetic confinement devices. While a large number of studies show that flux-tube codes provide an excellent approximation for turbulent transport in medium-large devi ...

IOP Publishing Ltd2023

Solar Wind Protons in the Diamagnetic Cavity at Comet 67P/Churyumov-Gerasimenko

Lucie Anemone Scharré

The plasma environment at a comet can be divided into different regions with distinct plasma characteristics. Two such regions are the solar wind ion cavity, which refers to the part of the outer coma that does not contain any solar wind ions anymore; and ...

AMER GEOPHYSICAL UNION2023

Predictive modeling of Alfvén eigenmode stability in inductive scenarios in JT-60SA

Javier García Hernández, Matteo Vallar, Antonio José Pereira de Figueiredo

The JT-60SA device offers unique conditions before ITER for the study of the interaction of energetic particles with plasma waves. With similar dimensions to JET, e.g., a major radius but with a slightly more elongated plasma volume, JT-60SA is used as a h ...

Frontiers Media Sa2023

On the Ohmic-dominant heating mode of capacitively coupled plasma inverted by boundary electron emission

Guang-Yu Sun, Haomin Sun

Electron emission from the boundary is ubiquitous in a capacitively coupled plasma (CCP) and precipitates nonnegligible influence on the discharge properties. Here, we present Particle-in-Cell/Monte Carlo Collision simulation of an Ohmic-dominant heating m ...

AIP American Institute of Physics2022

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

Olivier Sauter, Basil Duval, Stefano Coda, Patrick Blanchard, Benoît Labit, Joan Decker, Umar Sheikh, Cristian Galperti, Gergely Papp

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 ...

IOP Publishing Ltd2022

The Alfvenic nature of chromospheric swirls

Aleksi Antoine Bossart, Andrea Francesco Battaglia

Context. Observations show that small-scale vortical plasma motions are ubiquitous in the quiet solar atmosphere. They have received increasing attention in recent years because they are a viable candidate mechanism for the heating of the outer solar atmos ...

EDP SCIENCES S A2021

Edge turbulence in ISTTOK: a multi-code fluid validation

Paolo Ricci, Davide Galassi, Fabio Riva, Rogério Manuel Cabete De Jesus Jorge, Eric Serre

Fluid models used to study the edge plasma region need to be benchmarked against similar conditions given that models can strongly differ in complexity and therefore the results they produce. Via this validation study undertaken through the framework of EU ...

2021

Design optimization of the Upper Steering Mirror Assembly (USMA) for ITER ECHUL in view of disruptive events

Timothy Goodman, René Chavan, Matteo Vagnoni, Anastasia Xydou

Four Electron Cyclotron Heating Upper Launchers (ECHUL) will be used at ITER to counteract magneto-hydrodynamic plasma instabilities by targeting them with up to 20 MW of mm-wave power at 170 GHz. The millimeter waves are guided through a set of fixed mirr ...

2021

Plasma heating and generation of energetic D ions with the 3-ion ICRF + NBI scenario in mixed H-D plasmas at JET-ILW

Henri Weisen, Javier García Hernández

Dedicated experiments were conducted in mixed H-D plasmas in JET to demonstrate the efficiency of the 3-ion ICRF scenario for plasma heating, relying on injected fast NBI ions as the resonant ion component. Strong core localization of the RF power depositi ...

IOP Publishing Ltd2020

Impact of a companion and of chromospheric emission on the shape of chromosome maps for globular clusters

Carmela Lardo

Context. Globular clusters (GCs) host multiple populations of stars that are well-separated in a photometric diagram - the chromosome map - built from specific Hubble Space Telescope (HST) filters. Stars from different populations feature at various locati ...

EDP SCIENCES S A2020

First demonstration of real-time kinetic equilibrium reconstruction on TCV by coupling LIUQE and RAPTOR

Olivier Sauter, Jean-Marc Moret, Federico Alberto Alfredo Felici, Antoine Pierre Emmanuel Alexis Merle, Cristian Galperti, Francesco Carpanese

Kinetic equilibrium reconstruction (KER) in tokamaks is the solution of the free-boundary MHD equilibrium that best fits the external magnetic measurements and the internal plasma profiles as imposed from modeling and/or available internal measurements. In ...

IOP Publishing Ltd2020

Manufacturing, installation, commissioning, and first results with the 3D low-temperature co-fired ceramic high-frequency magnetic sensors on the Tokamak a Configuration Variable

Duccio Testa

Innovative high-frequency magnetic sensors have been designed and manufactured in-house for installation on the Tokamak a Configuration Variable (TCV), which are now routinely operational during the TCV experimental campaigns. These sensors combine the Low ...

2020

Kinetic-MHD stability of virtually collisionless plasmas

Samuel Lanthaler

The stability of pressure driven modes such as the 1/1 internal kink is known to depend sensitively on a multitude of physical effects such as toroidal rotation, kinetic effects due to thermal and suprathermal particle species and finite Larmor radius effe ...

EPFL2020