Publications de Basil Duval | EPFL Graph Search

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The impurity concentration in the tokamak divertor plasma is a necessary input for predictive scaling of divertor detachment, however direct measurements from existing tokamaks in different divertor plasma conditions are limited. To address this, we have a ...

Irradiations with 14 MeV fusion neutrons are planned at Joint European Torus (JET) in DT operations with the objective to validate the calculation of the activation of structural materials in functional materials expected in ITER and fusion plants. This st ...

With the increasing demand for analogue channel acquisition on the TCV tokamak, a new PCI based acquisition has been specified, designed, built and installed into our MDSplus acquisition environment. The design criteria were to not only improve the cost/channel, as compared to our conventional hub based acquisition (CAMAC), but to provide some distributed processing power to avoid the associated acquisition server saturation, both in terms of CPU and network bandwidth. These units were initially intended to

Fusion plasma regimes with a strongly radiating magnetic 𝑋 point are promising candidates to tackle the outstanding power exhaust challenge in reactor-scale devices. In this Letter, we report on a new type of 𝑋-point radiator, the XPTR (𝑋-point target radi ...

Plasma diagnostics often employ computerized tomography to estimate emissivity profiles from a finite, and often limited, number of line-integrated measurements. Decades of algorithmic refinement have brought considerable improvements, and led to a variety of employed solutions. These often feature an underlying, common structure that is rarely acknowledged or investigated. In this paper, we present a unifying perspective on sparse-view tomographic reconstructions for plasma imaging, highlighting how many i

This paper presents experimental results on the accessibility and the properties of plasmas with improved confinement in TCV. First, the H-mode threshold power is measured in Ohmic plasmas. Above an Ohmic threshold density, the threshold power increases with the density. A lower threshold density is found when additional electron cyclotron heating (ECH) is applied. At these low densities, the threshold power increases dramatically with decreasing density. Only a small fraction of the wide operational domain

On the Tokamak a Configuration Variable (TCV), electron internal transport barriers (eITBs) can be formed during a gradual evolution from a centrally peaked to a hollow current profile while all external actuators are held constant. The formation occurs ra ...

We present simultaneous profiles of the poloidal distribution of electron temperature and density (Te, ne), the poloidal emissivity distributions of a range of spectral lines together with the corresponding ion temperatures, Ti, in the TCV divertor plasma. ...

In this paper, we analyze heat transport in the JET tokamak using data from its high resolution ECE diagnostic and analyses based on the transfer entropy (TE). The analysis reveals that heat transport is not smooth and continuous, but is characterized by ' ...

The pressure gradient of the high confinement pedestal region at the edge of tokamak plasmas rapidly collapses during plasma eruptions called edge localised modes (ELMs), and then re-builds over a longer time scale before the next ELM. The physics that con ...

Tritium accumulation in fusion reactor materials is considered a serious radiological issue, therefore a lot of effort has been concentrated on the development of radiometric techniques. A novel method, based on gradual dissolution, for the determination o ...

Experiments with high-power electron cyclotron heating (ECH) and current drive (ECCD) in the TCV tokamak are discussed. Power up to 2.7 MW from six gyrotrons is delivered to the tokamak at the second-harmonic frequency (82.7 GHz) in X-mode. The power is transmitted to the plasma by six independent launchers, each equipped with steerable mirrors that allow a wide variety of injection angles in both the poloidal and toroidal directions. Fully non-inductive operation of the tokamak has been achieved in steady

A new gas puff imaging diagnostic has been installed on the TCV tokamak, providing two-dimensional insights into scrape-off-layer (SOL) turbulence dynamics above, at and below the magnetic X-point. A detailed study in L-mode, attached, lower single-null di ...

The Super-X Divertor (SXD) is an alternative divertor configuration leveraging total flux expansion at the Outer Strike Point (OSP). While the extended 2-Point Model (2PM) predicts facilitated detachment access and control in the SXD configuration, these a ...

Alfven eigenmodes driven by energetic particles are routinely observed in tokamak plasmas. These modes consist of poloidal harmonics of shear Alfven waves coupled by inhomogeneity in the magnetic field. Further coupling is introduced by 3D inhomogeneities ...

Results from the last FTU campaigns on RE mitigation strategies for quiescent and post-disruption RE beams are presented. We provide experimental evidence that for some RE quiescent scenarios D-2 solid pellets achieve complete RE suppression capability, ma ...

A multispectral camera setup is used to infer a 2D map of plasma parameters in a tokamak from spectral emissions. However, the light measured by these cameras is line integrated in the toroidal direction, whereas emissivities on the poloidal plane are nece ...

In DEMO reactor to produce electricity, a total installed power up to 150 MW is considered. In the heating mix, neutral beam (NB) injectors of high neutral particle energy (0.8-1 MeV) with high wall-plug efficiency (η in the range of 50% to 60%) will be required. Present design considered a NB system delivering in total 50 MW. In the Siphore NB concept [1], one of the promising candidates to meet these challenging requirements, negative ions will be extracted from a long, thin ion source 3 m high and 15 cm

The self-consistent core-pedestal prediction model of a combination of EPED1 type pedestal prediction and a simple stiff core transport model is able to predict Type I ELMy (edge localized mode) pedestals of a large JET-ILW (ITER-like wall) database at the ...

This paper focuses on interpreting variations in the NPA measured energy distribution of neutral fluxes from the TCV high density H-mode plasma discharges with strong third harmonic electron cyclotron heating (P_{X3}>P_{\Omega}). Two quasi-stationary regim ...

Basil Duval

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An assessment of nitrogen concentrations from spectroscopic measurements in the JET and ASDEX upgrade divertor

Activation Inventories After Exposure To Dd/Dt Neutrons In Safety Analysis Of Nuclear Fusion Installations

128 channel PCI-based data acquisition system for MDSplus

𝑋-Point Target Radiator Regime in Tokamak Divertor Plasmas

Tomography for plasma imaging: a unifying framework for Bayesian inference

Accessibility and properties of ELMy H-mode and ITB plasmas in TCV

Safety factor profile requirements for electron ITB formation in TCV

Interpretation of divertor ion temperature measurements from an attached towards a detached regime

Radial variation of heat transport in L-mode JET discharges

Pedestal evolution physics in low triangularity JET tokamak discharges with ITER-like wall

Novel method for determination of tritium depth profiles in metallic samples

High-power ECH and fully non-inductive operation with ECCD in the TCV tokamak

X-point and divertor filament dynamics from gas puff imaging on TCV

Parallel flows as a key component to interpret Super-X divertor experiments

Modification of the Alfven wave spectrum by pellet injection

Results on quiescent and post-disruption runaway electrons studies at Frascati Tokamak Upgrade: RE mitigation via solid deuterium pellets and anomalous Doppler instability

Machine learning enhanced tomographic reconstruction for multispectral imaging on TCV

A novel helicon plasma source for negative ion beams for fusion

Self-consistent pedestal prediction for JET-ILW in preparation of the DT campaign

Ion Temperature Fluctuations in ELMy H-mode of the X3 EC-heated Plasmas on TCV