Publications de Yves Martin | 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 ...

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 ...

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

An integrated radiative high performance scenario has been established at ASDEX Upgrade based on simultaneous feedback control of the average divertor neutral particle and power flux in combination with a high, pellet induced frequency of edge localized mo ...

Improvement of the spatial resolution of the TCV Thomson scattering system has permitted measurements of the pedestal height and gradient of electron density and temperature profiles near; the plasma boundary during ELMy H-mode. Measured profiles were fitt ...

In this study, beryllium tiles from Joint European Torus (JET) vacuum vessel wall were analysed and compared regarding their position in the vacuum vessel and differences in the exploitation conditions during two campaigns of ITER-Like-Wall (ILW) in 2011-2 ...

The addition of high power, low aspect ratio data from the NSTX and MAST experiments has motivated a new investigation of the effect of aspect ratio on confinement scaling. Various statistical methods, including those that incorporate estimates of measurem ...

The low temperature boundary layer plasma (scrape-off layer or SOL) between the hot core and the surrounding vessel determines the level of power loading, erosion and implantation of material surfaces, and thus the viability of tokamak-based fusion as an e ...

The physics of tokamak plasmas, in which electrons are heated by electron cyclotron heating (ECH) and whose current is driven by electron cyclotron current drive (ECCD), is investigated in this paper together with applications on tokamak A configuration variable (TCV) using modifications of the pressure and current profiles to improve the operational regimes. In order to explain the experimentally determined current drive efficiency and hard x-ray and electron cyclotron emission measurements, it is shown th

The prediction of the thermal energy confinement time, tau(th), for ITER size experiments is based on power law scalings obtained using data sets of present tokamak results in specific regimes, the most relevant being the ELMy H mode regime. A thorough statistical approach has provided a bust fit to these data with an estimation of the error bars which forms the basis for the ITER EDA design parameters. In this article the range of variation of the main parameters in the database are studied individually an

Accurate measurement of the nuclear environment within a test tritium breeding-blanket module of a fusion reactor is crucial to determine tritium production rates which are relevant to self-sufficiency of tritium fuel supply, tritium accountancy and also t ...

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 variety of techniques are being tested on ASDEX Upgrade for avoiding or reducing the divertor energy load caused by ELMs. Quiescent H-mode operation has been improved by operation with recently boronized vessel walls. Z(eff) values in QH-modes are now similar to2.5, comparable with those found in ELMy H-modes of similar density. Type It ELM operation has been generated in discharges with ICRF additional heating alone, thus demonstrating its compatibility with reactor-relevant low core momentum and particl

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, ...

A multi-purpose saddle coil system is proposed as part of a future upgrade of TCV (Tokamak à Configuration Variable). This system consists of 3 rows of 8 coils, each coil having independent power supplies, and provides simultaneously error field correction (EFC), resonant magnetic perturbation (RMP) and fast vertical control (VC). Other applications, like resistive wall mode (RWM) control and controlled plasma rotation, are also considered. Edge localized modes (ELM), related to the high confinement regime

Yves Martin

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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

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

Safety factor profile requirements for electron ITB formation in TCV

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

Integrated exhaust scenarios with actively controlled ELMs

Edge profiles of electron temperature and density during ELMy H-mode in ohmically heated TCV plasmas

Comparison of the structure of the plasma-facing surface and tritium accumulation in beryllium tiles from JET ILW campaigns 2011-2012 and 2013-2014

The role of aspect ratio and beta in H-mode confinement scalings

Investigation into the formation of the scrape-off layer density shoulder in JET ITER-like wall L-mode and H-mode plasmas

ECH physics and new operational regimes on TCV

Considerations on energy confinement time scalings using present tokamak databases and prediction for ITER size experiments

Testing of tritium breeder blanket activation foil spectrometer during JET operations

Current Research into Applications of Tomography for Fusion Diagnostics

ITER-relevant H-mode physics at ASDEX upgrade

Light impurity transport in JET ILW L-mode plasmas

A saddle coil system for TCV and RMP spectrum optimisation