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Stephan Brunner

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Publications associées (134)

Vlasov simulations of electron-ion collision effects on damping of electron plasma waves

Stephan Brunner, Trach-Minh Tran

Collisional effects can play an essential role in the dynamics of plasma waves by setting a minimum damping rate and by interfering with wave-particle resonances. Kinetic simulations of the effects of electron-ion pitch angle scattering on Electron Plasma ...

Amer Inst Physics2016

Padé approximation of the adiabatic electron contribution to the gyrokinetic quasi-neutrality equation in the ORB5 code

Stephan Brunner, Laurent Villard, Ben McMillan, Emmanuel Lanti, Julien Stanislas Pierre Dominski

This work aims at completing the implementation of a solver for the quasineutrality equation using a PadÃ© approximation in the global gyrokinetic code ORB5. Initially [Dominski, Ph.D. thesis, 2016], the Pade approximation was only implemented for the kine ...

2016

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

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

Linear multispecies gyrokinetic flux tube benchmarks in shaped tokamak plasmas

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

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

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

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

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

A bucket sort algorithm for the particle-in-cell method on manycore architectures

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

The Particle-In-Cell (PIC) method is effectively used in many scientific simulation codes. In order to optimize the performance of the PIC approach, data locality is required. This relies on efficient sorting algorithms. We present a bucket sort algorithm ...

Springer2016

How non-adiabatic passing electron layers of linear microinstabilities affect turbulent transport

Stephan Brunner, Laurent Villard, Julien Stanislas Pierre Dominski

The response of passing electrons in ion temperature gradient and trapped electron mode microturbulence regimes is investigated in tokamak geometry making use of the flux-tube version of the gyrokinetic code GENE. Results are obtained using two different e ...

Amer Inst Physics2015

Investigating profile stiffness and critical gradients in shaped TCV discharges using local gyrokinetic simulations of turbulent transport

Stephan Brunner, Olivier Sauter, Laurent Villard, Yann Camenen, Alessandro Marinoni, Gabriele Merlo

The experimental observation made on the TCV tokamak of a significant confinement improvement in plasmas with negative triangularity (delta < 0) compared to those with standard positive triangularity has been interpreted in terms of different degrees of pr ...

Iop Publishing Ltd2015

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

Collisionless microtearing modes in hot tokamaks: Effect of trapped electrons

Stephan Brunner, Laurent Villard

Collisionless microtearing modes have recently been found linearly unstable in sharp temperature gradient regions of large aspect ratio tokamaks. The magnetic drift resonance of passing electrons has been found to be sufficient to destabilise these modes a ...

Amer Inst Physics2015

Quantitative study of the trapped particle bunching instability in Langmuir waves

Stephan Brunner

The bunching instability of particles trapped in Langmuir waves is studied using Vlasov simulations. A measure of particle bunching is defined and used to extract the growth rate from numerical simulations, which are compared with theory [Dodin et al., Phy ...

Amer Inst Physics2015

Demonstrating the saturation of stimulated Brillouin scattering by ion acoustic decay using fully kinetic simulations

Stephan Brunner

The saturation of stimulated Brillouin scattering (SBS) by the decay to turbulence of the ion acoustic wave (IAW) that participates in the three-wave SBS interaction is demonstrated using a quasinoiseless one-dimensional numerical solution to the Vlasov-Ma ...

Amer Inst Physics2015

Generalized radiation boundary conditions in gyrotron oscillator modeling

Stephan Brunner, Stefano Alberti, Minh Quang Tran, Trach-Minh Tran, Jean-Philippe Hogge, Jérémy Genoud

A numerical procedure to implement a frequency-independent generalized non-reflecting radiation boundary conditions, GNRBC, based on the Laplace Transform, is described in details and tested successfully on a simple 2 frequency test problem. In the case of ...

Springer2015

Turbulence and zonal flow structures in the core and L-mode pedestal of tokamak plasmas

Stephan Brunner, Olivier Sauter, Trach-Minh Tran, Laurent Villard, Ben McMillan, Julien Stanislas Pierre Dominski, Gabriele Merlo

Zonal flows (ZF) play a crucial role in regulating ion temperature gradient (ITG) turbulence. In previous global gyrokinetic simulations [1] using the ORB5 code with the adiabatic electron model, it was observed that long-lived ZF structures, leading to a ...

IOP Publishing2014

On the non-stiffness of edge transport in L-mode tokamak plasmas

Stephan Brunner, Roland Behn, Basil Duval, Timothy Goodman, Olivier Sauter, Stefano Coda, Alexander Karpushov, Yann Camenen, Lucia Isabel Federspiel, Doohyun Kim, Gabriele Merlo, Antoine Pierre Emmanuel Alexis Merle, Donghyun Kim

Transport analyses using first-principle turbulence codes and 11/2-D transport codes usually study radial transport properties between the tokamak plasma magnetic axis and a normalized minor radius around 0.8. In this region, heat transport shows significa ...

Amer Inst Physics2014

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

Stephan Brunner, Laurent Villard

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

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

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

Finite ballooning angle effects on ion temperature gradient driven mode in gyrokinetic flux tube simulations

Stephan Brunner

This paper presents effects of finite ballooning angles on linear ion temperature gradient (ITG) driven mode and associated heat and momentum flux in Gyrokinetic flux tube simulation GENE. It is found that zero ballooning angle is not always the one at whi ...

Amer Inst Physics2014

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