Publications by Stephan Brunner

Modelling of ETG turbulent transport in the TCV pedestal

Stefano Coda, Stephan Brunner, Benoît Labit, Oleg Krutkin

Results of the first gyrokinetic simulations of the TCV pedestal are presented. Two discharges at varying levels of gas puffing are considered as input parameters for the local GENE simulations. Linear and nonlinear simulations are carried out for electron ...

2025

Particle-in-cell methods in edge plasma physics: the PICLS code

Laurent Villard, Stephan Brunner, Giovanni Di Giannatale

Over the past decades, multiple gyrokinetic codes have shown to be able to simulate turbulence and associated transport in the core of Tokamak devices. However, their application to the edge and scrape-off layer (SOL) region presents significant challenges ...

2025

A Quasilinear Model for Momentum Transport Including Rotation and Electron-scale Turbulence

Stephan Brunner, Haomin Sun, Justin Richard Ball

In a previous paper, a new gyrokinetic quasilinear model was proposed to study turbulent momentum transport in tokamaks with up-down asymmetric plasma shaping and toroidal flow shear (Sun et al 2024 Nuclear Fusion 64 036026). In this work, we start by appl ...

IOP Publishing Ltd2025

Numerical study of turbulent eddy self-interaction in tokamaks with low magnetic shear. Part I: Linear simulations

Stephan Brunner, Justin Richard Ball, Arnas Volcokas

This study examines the impact of low and zero magnetic shear, along with rational values ofsafety factor, on linear mode behavior in tokamak plasmas. We focus on how magnetic field linetopology and parallel domain length influence linear mode structures a ...

IOP Publishing Ltd2025

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

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

Global electromagnetic gyrokinetic simulations of internal transport barriers in reversed-shear tokamaks

Laurent Villard, Stephan Brunner, Justin Richard Ball, Moahan Murugappan, Giovanni Di Giannatale, Arnas Volcokas

Internal transport barriers (ITB) form through turbulence suppression, often observed when the safety factor profile exhibits an off-axis minimum. This work aims at improving our understanding of the conditions enabling the development of an ITB, using a m ...

2025

Reducing Turbulent Transport in Tokamaks by Combining Intrinsic Rotation and the Low Momentum Diffusivity Regime

Stephan Brunner, Haomin Sun, Justin Richard Ball

Based on the analysis of a large number of high-fidelity nonlinear gyrokinetic simulations, we propose a novel strategy to improve confinement in spherical tokamak plasmas by combining up-down asymmetric flux surface shaping with the Low Momentum Diffusivi ...

IOP Publishing Ltd2025

Effects of Kinetic Ballooning Modes on the electron distribution function in the core of high-performance tokamak plasmas

Stephan Brunner

This article is dedicated to study the physical causes of a long-standing issue experienced in different tokamak devices throughout the last decades: the observed discrepancies between electron cyclotron emission (ECE) and Thomson Scattering (TS) diagnosti ...

IOP Publishing Ltd2025

Nonlinear Effects in Fluctuation Short Pulse Reflectometry

Stefano Coda, Stephan Brunner, Oleg Krutkin

The fluctuation short pulse reflectometry diagnostic is simulated with the full-wave CUWA code for ad-hoc turbulence and simplified geometry. The nonlinear effects on the measurements are investigated while accounting for the plasma curvature, probing angl ...

IOP Publishing Ltd2025

Numerical study of turbulent eddy self-interaction in tokamaks with low magnetic shear. Part II: Nonlinear simulations

Stephan Brunner, Justin Richard Ball, Arnas Volcokas

Using local nonlinear gyrokinetic simulations and building up on linear results from acompanion paper (Volcokas 2024 Submitted for publication), we demonstrate that turbulenteddies can extend along magnetic field lines for hundreds of poloidal turns in tok ...

IOP Publishing Ltd2025