Publications de Stephan Brunner

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Experimental measurements of the turbulence amplitude utilizing a short pulse reflectometry method are presented. Two discharges with shaped plasma possessing opposite signs of triangularity are considered and a higher turbulence amplitude is found in the ...

The unique flexibility of TCV in plasma shaping has been exploited to address different aspects of tokamak physics in which the plasma shape may play a role. This paper summarizes the experiments undertaken in the TCV tokamak ("Tokamak à Configuration Variable") over the last decade in stability and transport and offers a comprehensive and integrated view of the various effects of plasma shape observed. For each of these effects, the relation between experimental results and theoretical predictions is stres

Electromagnetic waves that resonate with the cyclotron motion of electrons in a magnetized plasma can efficiently transfer their momentum and energy to the plasma. This is routinely used to heat or drive current in tokamak plasmas. The impact of this local ...

This work shows a self-consistent numerical model of ion cyclotron resonant heating (ICRH) in a plasma of arbitrary (2D or 3D) geometry. Effects of anisotropy and full shaping on both MHD equilibrium and the dielectric tensor are explored. In particular, it is shown that the dielectric tensor becomes dependent on poloidal angle. Also, the anisotropic effects dominate the dielectric tensor. Using single particle simulations it is demonstrated that anisotropy develops due to ICRH. The changing of the equilibr

In this paper, we investigate the effects of ion-scale turbulence-generated currents on the local safety factor profile under conditions of low magnetic shear and proximity to rational surfaces, relevant to internal transport barrier formation. Our results show that turbulent currents can generate stationary zonal magnetic potential corrugations, producing a stepped safety factor profile with extended regions of zero magnetic shear. This change significantly affects turbulence self-interaction, resulting in

A two-fold analysis of electromagnetic core tokamak instabilities in the framework of the gyrokinetic theory is presented. First principle theoretical foundations of the gyrokinetic theory are used to explain and justify the numerical results obtained with ...

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 ...

In order to address non-local effects in turbulent transport of magnetic-fusion devices, the gyrokinetic code GENE has been extended from a flux tube to a more global geometry. This global version of GENE includes radial variations of temperature and density profiles, as well as of magnetic equilibrium quantities. Non-periodic radial boundary conditions allow for profile evolution. Thanks to an interface with the MHD equilibrium code CHEASE, as well as the implementation of various types of source and sink

Kinetic effects have been implemented in the three-dimensional full-wave code LEMan. These allow modeling Landau damping as well as the Kinetic Alfvén Wave (KAW). Special attention has been taken on the exact computation of the parallel wave vector as it c ...

This manuscript discusses discretization of the Vlasov-Poisson system in 2D+2V phase space using high-order accurate conservative finite difference algorithms. One challenge confronting direct kinetic simulation is the significant computational cost associ ...

The mechanism for blob generation is detailed in the toroidal magnetized plasma of the TORPEX device [ Fasoli et al., Phys. Plasmas 13, 055902 (2006) ] using an experimental configuration, which features a plasma region dominated by a coherent wave and a r ...

In small-sized tokamaks, finite Larmor radius effects could lead to a significant discrepancy between gyrokinetic local flux-tube results and global ones. This has been highlighted by previous turbulent transport studies as in McMillan et al (2010 Phys. Re ...

The understanding and prediction of transport due to plasma microturbulence is a key open problem in modern plasma physics, and a grand challenge for fusion energy research. Ab initio simulations of such small-scale, low-frequency turbulence are to be base ...

JT-60SA is currently the world's largest superconducting tokamak. It accelerates the realization of fusion energy by supporting ITER exploitation and complementing it in addressing key physics and engineering issues for DEMO reactors. The main targets of JT-60SA are breakeven-equivalent high-temperature deuterium plasmas and high-βsteady-state plasmas. To achieve these goals, laser-aided diagnostics with high spatial resolution are essential for detailed physics studies. In Operation Phase 1, a tangential s

We introduce and derive the Fourier -enhanced 3D electrostatic field solver of the gyrokinetic full -f PIC code PICLS. The solver makes use of a Fourier representation in one periodic direction of the domain to make the solving of the system easily paralle ...

In tokamak experiments, sufficiently strong E x B flow shear reduces turbulent transport, thereby improving the prospects for fusion power plants. It is therefore of great importance to efficiently explore parameter space to find where strong plasma flow c ...

Considering the spectral problem of microinstabilities in a curved system, methods for solving the global gyrokinetic equation are presented for the simple case of a cylindrical plasma. They prove to be efficient for computing the full unstable spectrum of ion temperature gradient (ITG) type modes and have shown to be applicable to the two-dimensional integral equation of tokamak configurations. (C) 1998 American Institute of Physics.

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 ...

In the context of gyrokinetic flux-tube simulations of microturbulence in magnetized toroidal plasmas, different treatments of the magnetic equilibrium are examined. Considering the Cyclone DIII-D base case parameter set [Dimits et al., Phys. Plasmas 7, 96 ...

Stephan Brunner

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Validation of short-pulse reflectometry turbulence measurements with a synthetic diagnostic

Physics Insight and Performance Benefit from Plasma Shaping Experiments in MHD and Energy Transport in the TCV Tokamak

Electron-cyclotron resonance heating and current drive source for flux-driven gyrokinetic simulations of tokamaks

Monte Carlo ICRH simulations in fully shaped anisotropic plasmas

Turbulence-induced Safety Factor Profile Flattening at Rational Surfaces in Tokamaks with Low Magnetic Shear

First principles gyrokinetic analysis of electromagnetic plasma instabilities

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

Development of a Global Version of the Gyrokinetic Microturbulence Code GENE

Convolution and iterative methods applied to low frequency waves in 3D configurations

High-Order Accurate Conservative Finite Difference Methods For Vlasov Equations In 2D+2V

Mechanism for blob generation in the TORPEX toroidal plasma

Gyrokinetic analysis of radial dependence and global effects on the zero particle flux condition in a TCV plasma

The global version of the gyrokinetic turbulence code GENE

Laser-aided diagnostics of JT-60SA

Verification of the Fourier-enhanced 3D finite element Poisson solver of the gyrokinetic full-f code PICLS

A new quasilinear model for turbulent momentum transport in tokamaks with flow shear and plasma shaping

Global approach to the spectral problem of microinstabilities in a cylindrical plasma using a gyrokinetic model

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

Gyrokinetic simulations of shaping effects on turbulent heat and particle transport observed on the TCV tokamak

Clarifications to the limitations of the s-alpha equilibrium model for gyrokinetic computations of turbulence