Publications by Olivier Sauter

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The ITER ECRH system consists of 24 gyrotrons with up to 24 MW installed millimeter wave heating power at 170 GHz, power supplies, control system, transmission lines, one Equatorial and the four Upper Launchers. With its high frequency and small beam focus ...

Retrieving spatial distribution of plasma emissivity from line integrated measurements on tokamaks presents a challenging task due to ill-posedness of the tomography problem and limited number of the lines of sight. Modern methods of plasma tomography ther ...

A series of experimental observations of light impurity profiles was carried out in JET (Joint European Torus) ITER-like wall (ILW) L-mode plasmas in order to investigate their transport mechanisms. These discharges feature the presence of He-3, Be, C, N, ...

An overview of recent results obtained at the tokamak ASDEX Upgrade (AUG) is given. A work flow for predictive profile modelling of AUG discharges was established which is able to reproduce experimental H-mode plasma profiles based on engineering parameter ...

Measurements are reported of electromagnetic emission close to the cyclotron frequency of energetic ions in JET plasmas heated by waves in the ion cylotron range of frequencies (ICRF). Hydrogen was the majority ion species in all of these plasmas. The meas ...

A high-density, ELM-free, 'enhanced Dalpha' (EDA) H-mode has been demonstrated with Ohmic or RF heating on the Alcator C-Mod device. An allied 'low particle confinement' H-regime was also observed previously in 'Mk0' divertor experiments on JET. Initial attempts to recover similar states in the JET 'MkIIGB' divertor configuration are reported, employing appropriately shaped magnetic equilibria. Comparisons between cases with and without divertor cryopumping show enhanced edge sources tend to increase ELM fr

Turbulence and Transport Reduction with Negative Triangularity : Correlation ECE Measurements in TCV Due to turbulence, core energy transport in fusion devices such as tokamaks generally exceeds collisional transport by at least an order of magnitude. It is therefore crucial to understand the instabilities driving the turbulent state and to find ways to control them. Plasma shape is one of these fundamental tools. In low collisionality plasmas, such as in a reactor, changing the plasma shape from Dee-shape

After a 26-month vent ASDEX Upgrade (AUG) went back in operation with a newly designed upper W-divertor suitable for alternative divertor configurations (featuring in-vessel coils and cryo-pump). Parameter scans and an extensive set of measurements were obtained and their interpretation is ongoing. Prompted by the ITER wall change, dedicated experiments on non-boronized plasma startup were contrasted to that employing asymmetric and more symmetric boronizations. The asymmetric boronization proved to be as b

A new set of analytical formulae for calculating the bootstrap current and the neoclassical conductivity in tokamak experiments is presented. Previous works comparing the widely used Sauter model with results of recently developed numerical neoclassical so ...

Localized electron heating and current drive, like those produced by electron cyclotron heating (ECH) systems, are powerful tools for controlling the sawtooth period. They allow the direct modification of the plasma parameters which determine the sawtooth stability. In this paper we report a set of new experimental results obtained in the TokamakConfiguration Variable (TCV) and a set of related simulations obtained applying a sawtooth period model in a transport code. The TCV device, equipped with a very fl

The plasma control system (PCS) of a long-pulse tokamak must be able to handle multiple control tasks simultaneously, and must be capable of robust event handling with a limited set of actuators. For ITER, this is particularly challenging given the large n ...

Global gradient driven gyrokinetic simulations performed with the Gyrokinetic Electromagnetic Numerical Experiment (GENE) code are used to investigate Tokamak a configuration variable (TCV) plasmas with negative triangularity. Considering limited L-mode pl ...

Interaction of waves in the ion cyclotron range of frequencies (ICRF) with a plasma has a number of key properties that make them attractive beyond pure heating. First, the waves can interact resonantly with either the plasma ions or electrons. In the case of ion cyclotron damping, a small number of resonant ions are often accelerated to high energies. These ions, apart from heating the bulk plasma via Coulomb collisions, can increase fusion reactivity, affect plasma stability and drive current. They have a

Understanding the details of the correlation between time series is an essential step on the route to assessing the causal relation between systems. Traditional statistical indicators, such as the Pearson correlation coefficient and the mutual information, ...

Electron cyclotron emission (ECE) diagnostics on Tokamak a Configuration Variable (TCV) allow study of the electron temperature evolution in time with good spatial and temporal resolution at the high field side and low field side at various lines of sight. ...

Neoclassical tearing modes are one of the most serious concerns for operation on a next-step tokamak device. The modes occur on present tokamaks at normalized pressure (beta (N)) values comparable to those envisaged For baseline scenarios in future devices, such as ITER-FEAT. Further, empirical scalings based on data from many of the present machines point to much lower thresholds on a larger device. However, physics-based models indicate an important role for the seed island mechanisms, which may in fact g

Estimation of the dynamic evolution of the electron plasma density during a tokamak discharge is crucial since it directly affects the plasma performance, confinement and stability. Therefore it needs to be monitored and controlled. Knowledge of the densit ...

Diagnostic alkali atom (e.g., lithium) beams are routinely used to diagnose magnetically confined plasmas, namely, to measure the plasma electron density profile in the edge and the scrape off layer region. A light splitting optics system was installed int ...

Two high performance JET-ILW pulses, pertaining to the 2016 experimental campaign, have been numerically simulated with the self-consistent code COREDIV with the aim of predicting the ELM-averaged power load to the target when extrapolated to DT plasmas. T ...

The density limit is investigated in the DIII-D negative triangularity plasmas which lack a standard H-mode edge. We find the limit may not be a singular disruptive boundary but a multifaceted density saturation phenomenon governed by distinct core and edge transport mechanisms. Sustained, non-disruptive operation is achieved at densities up to 1.8 times the Greenwald limit ( n G ) until the termination of auxiliary heating. Systematic power scans show distinct power scalings for the core ( n e ∝ P SOL 0.27

Olivier Sauter

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Nearing final design of the ITER EC H&CD Upper Launcher

Current Research into Applications of Tomography for Fusion Diagnostics

Light impurity transport in JET ILW L-mode plasmas

Progress from ASDEX Upgrade experiments in preparing the physics basis of ITER operation and DEMO scenario development

Observations and modelling of ion cyclotron emission observed in JET plasmas using a sub-harmonic arc detection system during ion cyclotron resonance heating

ELM moderation with ICRF heating on JET

Transport and turbulence reduction with negative triangularity : Correlation ECE measurements in TCV

Overview of the ASDEX Upgrade results

A new set of analytical formulae for the computation of the bootstrap current and the neoclassical conductivity in tokamaks

Effects of localized electron heating and current drive on the sawtooth period

Tokamak-agnostic actuator management for multi-task integrated control with application to TCV and ITER

Nonlocal effects in negative triangularity TCV plasmas

Application of ICRF waves in tokamaks beyond heating

On the Use of Transfer Entropy to Investigate the Time Horizon of Causal Influences between Signals

Recent electron cyclotron emission results on TCV

Neoclassical tearing modes

Model-based electron density estimation using multiple diagnostics on TCV

Sub-millisecond electron density profile measurement at the JET tokamak with the fast lithium beam emission spectroscopy system

COREDIV numerical simulation of high neutron rate JET-ILW DD pulses in view of extension to JET-ILW DT experiments

Disentangling core and edge mechanisms of the density limit in DIII-D negative triangularity plasmas