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Laurent Villard

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Related publications (144)

Mode excitation by an antenna in global gyrokinetic simulations

Stephan Brunner, Laurent Villard, Alberto Bottino, Ben McMillan, Emmanuel Lanti, 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

Experimental observations of modes with geodesic acoustic character from the core to the edge in the TCV tokamak

Stephan Brunner, Laurent Villard, Stefano Coda, Benoît Labit, Christian Gabriel Theiler, Zhouji Huang, Gabriele Merlo

2018

Investigating the radial structure of axisymmetric fluctuations in the TCV tokamak with local and global gyrokinetic GENE simulations

Stephan Brunner, Laurent Villard, Stefano Coda, Laurie Porte, Julien Stanislas Pierre Dominski, Gabriele Merlo, Matteo Fontana

2018

Gradient- and flux-driven global gyrokinetic simulations of ITG and TEM turbulence with an improved hybrid kinetic electron model

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

2018

Prediction of the Inter-Node Communication Costs of a New Gyrokinetic Code with Toroidal Domain

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

We consider the communication costs of gyrokinetic plasma physics simulations running at large scale. For this we apply virtual decompositions of the toroidal domain in three dimensions and additional domain cloning to existing simulations done with the OR ...

SPRINGER INTERNATIONAL PUBLISHING AG2018

Verification of Gyrokinetic codes: Theoretical background and applications

Laurent Villard, Alberto Bottino

In fusion plasmas, the strong magnetic field allows the fast gyro-motion to be systematically removed from the description of the dynamics, resulting in a considerable model simplification and gain of computational time. Nowadays, the gyrokinetic (GK) code ...

Amer Inst Physics2017

An arbitrary wavelength solver for global gyrokinetic simulations. Application to the study of fine radial structures on microturbulence due to non-adiabatic passing electron dynamics

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

The influence of the fine layers of the non-adiabatic passing electron response on electrostatic turbulent transport, previously studied systematically in flux tube geometry [Dominski et al., Phys. Plasmas 22, 062303 (2015)], is pursued in global geometry ...

Amer Inst Physics2017

Modelling of advanced three-ion ICRF heating and fast ion generation scheme for tokamaks and stellarators

Wilfred Anthony Cooper, Laurent Villard, Jonathan Graves, David Pfefferlé, Jonathan Marc Philippe Faustin, Samuel Lanthaler

Absorption of ion-cyclotron range of frequencies waves at the fundamental resonance is an efficient source of plasma heating and fast ion generation in tokamaks and stellarators. This heating method is planned to be exploited as a fast ion source in the We ...

2017

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

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

The negative triangularity tokamak: stability limits and prospects as a fusion energy system

Ambrogio Fasoli, Olivier Sauter, Laurent Villard, Andrei Martynov

The paper discusses edge stability, beta limits and power handling issues for negative triangularity tokamaks. The edge magnetohydrodynamic stability is the most crucial item for power handling. For the case of negative triangularity the edge stability pic ...

IOP Publishing Ltd2015

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

Status of the benchmark activity of ICRF full-wave codes within EUROfusion WPCD and beyond

Olivier Sauter, Laurent Villard

As follow-up of the benchmark activity of ICRF full-wave codes within the EUROfusion Code Development for Integrated Modelling project (WPCD), a simple-to-complex approach has been devised for verification of the European ICRF codes, imported in the Europe ...

Amer Inst Physics2015

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

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

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