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Stephan Brunner

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Publications associées (128)

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Linearized Coulomb Collision Operator for Simulation of Interpenetrating Plasma Streams

Stephan Brunner

We present an extension of a linearized Coulomb collision operator, previously used in several Eulerian kinetic codes for like-species collisions and unlike-species collisions in the case where the backgrounds about which the linearization is made all are ...

IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC2019

How eigenmode self-interaction affects zonal flows and convergence of tokamak core turbulence with toroidal system size

Stephan Brunner, Gabriele Merlo, Justin Richard Ball, Julien Stanislas Pierre Dominski, Ajay Chandrarajan Jayalekshmi

Self-interaction is the process by which a microinstability eigenmode that is extended along the direction parallel to the magnetic field interacts non-linearly with itself. This effect is particularly significant in gyrokinetic simulations accounting for ...

Cambridge University Press2020

Global gyrokinetic stability of collisionless microtearing modes in large aspect ratio tokamaks

Laurent Villard, Stephan Brunner

Linear full radius gyrokinetic calculations show the existence of unstable microtearing modes (MTMs) in purely collisionless, high temperature, large aspect ratio tokamak plasmas. The present study takes into account fully gyrokinetic highly passing ions a ...

Amer Inst Physics2014

A portable platform for accelerated PIC codes and its application to GPUs using OpenACC

Laurent Villard, Stephan Brunner, Emmanuel Lanti, Trach-Minh Tran, Claudio Gheller

We present a portable platform, called PIC_ENGINE, for accelerating Particle-In-Cell (PIC) codes on heterogeneous many-core architectures such as Graphic Processing Units (GPUs). The aim of this development is efficient simulations on future exascale syste ...

Elsevier Science Bv2016

New insights into the decay of ion waves to turbulence, ion heating, and soliton generation

Stephan Brunner

The decay of a single-frequency, propagating ion acoustic wave (IAW) via two-ion wave decay to a continuum of IAW modes is found to result in a highly turbulent plasma, ion soliton production, and rapid ion heating. Instability growth rates, thresholds, an ...

Amer Inst Physics2014

The transition from thermally driven to ponderomotively driven stimulated Brillouin scattering and filamentation of light in plasma

Stephan Brunner

The dispersion properties of ion acoustic waves and their nonlinear coupling to light waves through ponderomotive and thermal forces are sensitive to the strength of electron-ion collisions. Here, with the neglect of electron-electron collisions, the growt ...

2005

Global collisional gyrokinetic simulations of ITG microturbulence starting from a neoclassical equilibrium

Olivier Sauter, Laurent Villard, Stephan Brunner, Trach-Minh Tran, Alberto Bottino, Sébastien Jolliet, Ben McMillan, Thibaut Vernay

Linearized operators describing inter-species and like-species collisions have been discretized and implemented in the gyrokinetic Particle-In-Cell (PIC) code ORB5 [S. Jolliet, Comp. Phys. Comm. 177, 409 ( 2007)] based on the delta-f approach. Simulation r ...

Iop Publishing Ltd, Dirac House, Temple Back, Bristol Bs1 6Be, England2010

Linear multispecies gyrokinetic flux tube benchmarks in shaped tokamak plasmas

Olivier Sauter, Laurent Villard, Stephan Brunner, Yann Camenen, Emiliano Fable, Gabriele Merlo, Alice Burckel

Verification is the fundamental step that any turbulence simulation code has to be submitted in order to assess the proper implementation of the underlying equations. We have carried out a cross comparison of three flux tube gyrokinetic codes, GENE [F. Jen ...

2016

Identifying the role of non-adiabatic passing electrons in ITG/TEM microturbulence by comparing fully kinetic and hybrid electron simulations

Stephan Brunner, Julien Stanislas Pierre Dominski

The response of passing electrons in Ion Temperature Gradient (ITG) and Trapped Electron Mode (TEM) microinstability regimes is investigated in tokamak geometry making use of the flux-tube version of the gyrokinetic code GENE [Jenko et al. 2000 Phys. Plasm ...

IOP Publishing Ltd2012

Collisional damping rates for electron plasma waves reassessed

Stephan Brunner, Trach-Minh Tran

Collisional damping of electron plasma waves, the primary damping for high phase velocity waves, is proportional to the electron-ion collision rate, nu(ei,th). Here, it is shown that the damping rate normalized to nu(ei,th) depends on the charge state, Z, ...

Amer Physical Soc2017

Linear theory of electron-plasma waves at arbitrary collisionality

Paolo Ricci, Stephan Brunner, Rogério Manuel Cabete De Jesus Jorge

The dynamics of electron-plasma waves is described at arbitrary collisionality by considering the full Coulomb collision operator. The description is based on a Hermite–Laguerre decomposition of the velocity dependence of the electron distribution function ...

Cambridge University Press2019

Towards the optimization of a gyrokinetic Particle-In-Cell (PIC) code on large-scale hybrid architectures

Laurent Villard, Stephan Brunner, Emmanuel Lanti, Trach-Minh Tran, Noé Thomas Elie Ohana, Claudio Gheller

With the aim of enabling state-of-the-art gyrokinetic PIC codes to benefit from the performance of recent multithreaded devices, we developed an application from a platform called the "PIC-engine" [1, 2, 3] embedding simplified basic features of the PIC me ...

2016

Experimental characterization of drift-interchange instabilities in a simple toroidal plasma

Ambrogio Fasoli, Ivo Furno, Benoît Labit, Stephan Brunner, Mario Ludovico Podesta, Francesca Maria Poli, Gennady Plyushchev

Low frequency electrostatic instabilities are investigated on TORPEX [Fasoli, Labit, McGrath, Muller, Podesta, and Poli, Bull. Am. Phys. Soc. 48, 119 (2003)], a toroidal device for basic plasma physics experiments with a toroidal magnetic field 100 mT and ...

2006

Kinetic simulations and reduced modeling of longitudinal sideband instabilities in non-linear electron plasma waves

Stephan Brunner, Loïc Hausammann

Kinetic Vlasov simulations of one-dimensional finite amplitude Electron Plasma Waves are performed in a multi-wavelength long system. A systematic study of the most unstable linear sideband mode, in particular its growth rate gamma and quasi- wavenumber de ...

Amer Inst Physics2014

Mode excitation by an antenna in global gyrokinetic simulations

Laurent Villard, Stephan Brunner, Emmanuel Lanti, Alberto Bottino, Ben McMillan, Noé Thomas Elie Ohana

In order to get a better understanding of the linear and non-linear plasma interaction of microinstabilities and associated turbulence with different specific modes, an antenna is implemented in the global gyrokinetic code ORB5. It consists in applying an ...

2018

Resonance between heat-carrying electrons and Langmuir waves in inertial confinement fusion plasmas

Stephan Brunner

In ignition scale hot plasmas, temperature gradients and thermal transport modify electron distributions in a velocity range resonant with Langmuir waves typical of those produced by stimulated Raman scattering. We examine the resultant changes to the Land ...

Amer Inst Physics2016

Multi-dimensional Vlasov simulations and modeling of trapped-electron-driven filamentation of electron plasma waves

Stephan Brunner

Kinetic simulations of two-dimensional finite-amplitude electron plasma waves are performed in a one-wavelength long system. A systematic study of the most unstable linear sideband mode, in particular its growth rate gamma and wavenumber k(y), is carried o ...

Amer Inst Physics2015

Collisional effects on positive and negative triangularity through local and global temperature gradient-driven and flux-driven gyrokinetic simulations

Laurent Villard, Stephan Brunner, Moahan Murugappan, Giovanni Di Giannatale, Alessandro Balestri

In this work, we explore the effects of collisions on turbulent transport, focusing on two different TCV magnetic equilibria featuring positive and negative triangularity. The investigation is conducted using gyrokinetic modeling. Both gradient-driven and ...

2025

Ultra long turbulent eddies, magnetic topology, and the triggering of internal transport barriers in tokamaks

Stephan Brunner, Justin Richard Ball, Arnas Volcokas

Local nonlinear gyrokinetic simulations of tokamak plasmas demonstrate that turbulent eddies can extend along magnetic field lines for hundreds of poloidal turns when the magnetic shear is very small. By accurately modeling different field line topologies ...

IOP Publishing Ltd2023

Gyrokinetic simulations on many- and multi-core architectures with the global electromagnetic Particle-In-Cell Code ORB5

Laurent Villard, Stephan Brunner, Emmanuel Lanti, Noé Thomas Elie Ohana, Claudio Gheller

Gyrokinetic codes in plasma physics need outstanding computational resources to solve increasingly complex problems, requiring the effective exploitation of cutting-edge HPC architectures. This paper focuses on the enabling of ORB5, a state-of-the-art, fir ...

2021