Publications de Olivier Sauter

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Numerical computations of ITER equilibria in the hybrid scenario using a three-dimensional (3D) magnetohydrodynamic equilibrium code with nested magnetic flux surfaces demonstrate the formation of internal 3D helical cores similar to saturated ideal intern ...

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 ...

Tokamaks allow to confine fusion plasma with magnetic fields. The prediction/reconstruction of the last closed-flux surface (LCFS) is one of the primary challenges in the control of the magnetic configuration. The evolution in time of the LCFS is determine ...

A common feature of the Vlasov equation is that it develops fine-scale filamentation as time evolves, as observed, for example, in global nonlinear simulations of the ion-temperature-gradient instability. From a numerical point of view, it is not trivial t ...

In the TCV tokamak, the m/n = 2/1 island is observed in low-density discharges with central electron-cyclotron current drive. The evolution of its width has two distinct growth phases, one of which can be linked to a "conventional" tearing mode driven unstable by the current profile and the other to a neoclassical tearing mode driven by a perturbation of the bootstrap current. The TCV results provide the first clear observation of such a destabilization mechanism and reconcile the theory of conventional and

Reliable algorithms for disruption avoidance and prediction are foreseen to play a fundamental role in the JET control system for the successful operation of the machine in the upcoming deuterium-tritium campaigns. The integration of such algorithms is exp ...

Neoclassical tearing modes (NTMs) are magnetic islands which increase locally the radial transport and therefore degrade the plasma performance. They are self-sustained by the bootstrap current perturbed by the enhanced radial transport. The confinement de ...

JET returned to deuterium-tritium operations in 2023 (DTE3 campaign), approximately two years after DTE2. DTE3 was designed as an extension of JET’s 2022-2023 deuterium campaigns, which focused on developing scenarios for ITER and DEMO, integrating in-dept ...

The ideal stability of the internal kink mode is analysed for realistic tokamak geometry. Accurate numerical results demonstrate convergence with Bussac's toroidal solution (Bussac M N, Pellat R Edery D and Soule J L 1975 Phys. Rev. Lett. 35 1638) for inve ...

The electron temperature and density pedestals tend to vary in their relative radial positions, as observed in DIII-D (Beurskens et al 2011 Phys. Plasmas 18 056120) and ASDEX Upgrade (Dunne et al 2017 Plasma Phys. Control. Fusion 59 14017). This so-called ...

Recently, an experimental campaign has been launched on TCV with the aim of exploring and extending the limits of the operating space. The vertical position control system has been optimized, with the help of extensive model calculations, in order to allow operation at the lowest possible stability margin. In addition, the growth rate of the axisymmetric instability has been minimized by choosing optimum values for the plasma triangularity and squareness and by operating close to the current limit imposed b

The impact of the finite grid size in SOLPS-ITER edge plasma simulations is assessed for JET H-mode discharges with a metal wall. For a semi-horizontal divertor configuration it is shown that the separatrix density is at least 30% higher when a narrow scra ...

Carbon impurity transport is studied in the TCV tokamak using a charge exchange recombination diagnostic. TCVs flexible shaping capabilities were exploited to extend previous impurity transport studies to negative triangularity (delta < 0). A practical way ...

An optimized plasma current ramp-down strategy is critical for safe and fast termination of plasma discharges in a tokamak demonstration fusion reactor (DEMO), both in planned and emergency scenarios, avoiding plasma disruptions and excessive heat loads to ...

Simulations of the plasma current density evolution in electron internal transport barrier discharges on the Tokamak a Configuration Variable (TCV) have been performed, in order to determine the relationship between the safety-factor profile and the electr ...

The first experimental evidence of parallel momentum transport generated by the up-down asymmetry of a toroidal plasma is reported. The experiments, conducted in the Tokamak a` Configuration Variable, were motivated by the recent theoretical discovery of i ...

The paper describes the operation and upgrade of the Heating Neutral Beam Injection (HNBI) system as well as the related infrastructure at the Tokamak Configuration Variable (TCV) during the last years. In 2023, the installation of new TCV neutron shieldin ...

Recent studies (Maggi et al 2015 Nucl. Fusion 55 113031; Maggi et al 2017 Nucl. Fusion 57 116012) have shown that on JET with the Be/W ITER-like wall (JET-ILW) in high beta discharges with high D-2 gas rates, the inter-ELM temperature pedestal growth is sa ...

In a tokamak fusion reactor the energetic alpha particles will transiently stabilize the magnetohydrodynamic activity causing sawtooth oscillations. The crash events terminating long sawtooth free periods can provide seed islands for neoclassical tearing modes [O. Sauter et al., Phys. Rev. Lett. 88, 105001 (2002)]. To shorten the sawtooth periods localized current drive near the q=1 surface is a possibility. This Letter provides the first experimental evidence for the effectiveness of this method in the dif

We aim to simulate the bootstrap current for a MAST-like spherical tokamak using two approaches for magnetic equilibria including externally caused 3D effects such as resonant magnetic perturbations (RMPs), the effect of toroidal ripple, and intrinsic 3D e ...

Olivier Sauter

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Helical ITER hybrid scenario equilibria

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

A machine-learning-based tool for last closed-flux surface reconstruction on tokamaks

Fine-scale structures and negative-density regions: Comparison of numerical methods for solving the advection equation

From current-driven to neoclassically driven tearing modes

A First Analysis of JET Plasma Profile-Based Indicators for Disruption Prediction and Avoidance

On the Requirements to Control Neoclassical Tearing Modes in Burning Plasmas

Overview of the third JET deuterium-tritium campaign

The stability of the ideal internal kink mode in realistic tokamak geometry

Effect of the relative shift between the electron density and temperature pedestal position on the pedestal stability in JET-ILW and comparison with JET-C

Extension of the TCV operating space towards higher elongation and higher normalized current

On the role of finite grid extent in SOLPS-ITER edge plasma simulations for JET H-mode discharges with metallic wall

Study of impurity C transport and plasma rotation in negative triangularity on the TCV tokamak

Scenario optimization for the tokamak ramp-down phase in RAPTOR. Part B: safe termination of DEMO plasmas

Current density evolution in electron internal transport barrier discharges in TCV

Experimental Evidence of Momentum Transport Induced by an Up-Down Asymmetric Magnetic Equilibrium in Toroidal Plasmas

Present status of heating neutral beam injection system at TCV

Inter-ELM evolution of the edge current density in JET-ILW type I ELMy H-mode plasmas

Destabilization of fast-ion-induced long sawteeth by localized current drive in the JET tokamak

Simulation of bootstrap current in 2D and 3D ideal magnetic fields in tokamaks