Publications by Yves Martin | EPFL Graph Search

Chat with Graph Search

Ask any question about EPFL courses, lectures, exercises, research, news, etc. or try the example questions below.

DISCLAIMER: The Graph Chatbot is not programmed to provide explicit or categorical answers to your questions. Rather, it transforms your questions into API requests that are distributed across the various IT services officially administered by EPFL. Its purpose is solely to collect and recommend relevant references to content that you can explore to help you answer your questions.

The D-alpha emission time-series from the TCV tokamak was investigated fora large set of ELMy discharges, to determine whether fluctuations in the time delay between ELMs are the result of noise only, or whether a deterministic process in a chaotic state exists, as suggested by results on JT-60U (Bak et al 1999 Phys. Rev. Lett. 83 1339). This study was carried out by searching the time-series of each discharge for transient sequences that are generic to chaotic systems, called unstable periodic orbits (UPOs

A set of experiments was carried out in JET ILW (Joint European Torus with ITER-Like Wall) L-mode plasmas in order to study the effects of light impurities on core ion thermal transport. N was puffed into some discharges and its profile was measured by act ...

Growth rates of the axisymmetric instability of elongated plasmas in TCV are measured, in open loop configuration, for a wide variety of plasma shapes with elongations and triangularities in the ranges 1.3 < kappa < 2.2 and -0.3 < delta < 0.6, respectively, and for stability margins covering the range 1.03 < f < 1.60. In addition, the stability of the vertical position control system is investigated experimentally, under closed loop conditions, by varying the feedback gains and by measuring the oscillation

In the moderate magneticfield of TCV (1.5T), the recently installed X3 system (3 gyrotrons @118 GHz, 0.45 MW/each, 2s) broadens the operational space with the possibility of heating plasmas at high density, well above the cutoff density of the X2 system (X ...

The First Mirror Test for ITER has been carried out in JET with mirrors exposed during: (i) the third ILW campaign (ILW-3, 2015-2016, 23.33 h plasma) and (ii) all three campaigns, i.e. ILW-1 to ILW-3: 2011-2016, 63,52 h in total. All mirrors from main cham ...

The upgrade project for TCV (Tokamak à Configuration Variable) includes the installation of a set of saddle coils, namely the saddle coil system (SCS), located and powered such as to create a helical magnetic perturbation. Using independent power supplies, ...

During the first two years of operation, the TCV tokamak has produced a large variety of plasma shapes and magnetic configurations, with 1.0 less than or equal to B-tor less than or equal to 1.46T, I-p less than or equal to 800kA, kappa less than or equal to 2.05, -0.7 less than or equal to delta less than or equal to 1. A new shape control algorithm, based on a finite element reconstruction of the plasma current in real time, has been implemented. Vertical growth rates up to 1000 s(-1) have been stabilized

Particle transport in tokamak plasmas has been intensively studied in the past, particularly in relation to density peaking and the presence of anomalous inward particle convection in L-and H-modes. While in the L-mode case the presence of the anomalous in ...

Magnetic triggering of edge localized modes (ELMs) was reported first from TCV in ohmic plasmas showing type-III ELMs. This method, showing successful locking of the ELM frequency to an imposed vertical plasma oscillation, has now also been demonstrated in the ITER-relevant type-I ELM regime in ASDEX Upgrade. Our experiments showed the ELM frequency becoming identical to the driving frequency in steady state for an applied motion of only about twice the value caused by an intrinsic ELM event. Triggered ELMs

Empirical estimates indicate that the transient divertor power load induced by type-I ELMs in the standard H-mode ITER scenario might result in intolerably short target life times. Significant experimental effort has been put on the exploration of recipes ...

Precise control of the shape and position of double-null divertor configurations in the TCV tokamak has been used to trigger reliably the transition from ELM-free to ELMy ohmic H mode and back. Preprogrammed modulation of the magnetic axis height (+/- 1.25 cm), with fixed shaping field, caused the plasma to evolve, during a single discharge, between double-null-upper, double-null and double-null-lower configurations, with the secondary X point remaining close to the separatrix. The transition from ELM-free

The overlap of pulses in the pedestal database and the global H-mode confinement database has been increased. This has resulted in a new improved combined dataset with core and pedestal energy data. Regression analysis of this dataset indicates that in ELMy H-mode the pedestal energy scales differently from the core energy and degrades strongly with plasma pressure β. Using these regression results to estimate the pedestal energy in the full ELMy dataset of the global H-mode confinement database, a new two-

An analysis of the effect of magnetic geometry on heat flux in a wide range of single null diverted discharge configurations with 1.5 < κ(95) < 2.2, 0.2 < δ(95) < 0.45 suggests that elongation is beneficial for confinement. If heat diffusivities are assumed not to depend on plasma shape., the predicted exponent for a power law scaling with elongation is alpha(kappa) approximate to 0.74, based on the configurations in the study. This is very close to dependences from the ITER database for dischar

L-mode to H-mode (LH) transitions are observed in a large variety of plasma conditions in TCV Ohmic plasmas. The power flowing through the separatrix at the LH transition differs by up to a factor of two from the predicted H-mode threshold power. Variations in this deviation are due to the large operational domain covered by the transitions as well as from the different scenarios identified to access the H-mode regime. LH. transitions obtained during the plasma current ramp at low plasma current, elongation

Current profile tailoring has been performed by application of electron cyclotron heating (ECH) and electron cyclotron current drive, leading to improved energy confinement in the plasma core of the TCV tokamak. The improved confinement is characterized by a substantial enhancement (H-factor) of the global electron energy confinement time relative to the prediction of the RLW scaling law (Rebut P H et al 1989 Proc. 12th Int. Conf. of Plasma Physics and Controlled Fusion Research (Nice, 1988) vol 2 (Vienna:

During plasma excitation by high power Alfven waves at TCA, signals at harmonics of the generator frequency are observed in the plasma scrape-off layer. In this paper, experimental investigations of the sheath effect and the excitation efficiency and dispersion properties of the harmonics are reported. The results indicate that the harmonics arise, either directly or indirectly, through the driven Alfven waves and not through the sheath effect at the exciting antenna. The RF ion saturation current is observ

Block-structured mesh generation techniques have been well addressed in the CFD community for automobile and aerospace studies, and their applicability to magnetic fusion is highly relevant, due to the complexity of the plasma-facing wall structures inside ...

Within the range of plasma shapes and plasma currents investigated, the electron confinement time, Tau_E increases with density, elongation and negative triangularity (-0.4

The aim of this paper is to present a signal processing algorithm that, applied to the raw Locked Mode signal, allows us to obtain a disruption indicator in principle exploitable on different tokamaks. A common definition of such an indicator for different ...

ERO is a 3D Monte-Carlo impurity transport and plasma-surface interaction code. In 2011 it was applied for the ITER first wall (FW) life time predictions [1] (critical blanket module BM11). After that the same code was significantly improved during its app ...

Yves Martin

Chat with Graph Search

Dynamics of edge localized modes in the TCV tokamak

Effects of nitrogen seeding on core ion thermal transport in JET ILW L-mode plasmas

Vertical position control in TCV: Comparison of model predictions with experimental results

Third-harmonic X-mode, real-time controlled top-launch ECW experiments on TCV tokamak

First mirror test in JET for ITER: Complete overview after three ILW campaigns

Physics design of a saddle coil system for TCV

Recent Results from the Tcv Tokamak

Observation of enhanced ion particle transport in mixed H/D isotope plasmas on JET

Frequency control of type-I ELMs by magnetic triggering in ASDEX Upgrade

Local 3D perturbation experiments for probing the ELM stability

Elm Control During Double-Null Ohmic H Modes in Tcv

Development of a two-term model for the confinement in ELMy H-modes using the global confinement and pedestal databases

On the dependence of energy confinement on elongation in single null divertor plasmas

H-mode threshold power in TCV Ohmic plasmas

Control of electron internal transport barriers in TCV

An Experimental-Study of the Harmonics Generated During Alfven-Wave Heating at Tca

A wall-aligned grid generator for non-linear simulations of MHD instabilities in tokamak plasmas

Preliminary Confinement Studies during ECRH in TCV

A locked mode indicator for disruption prediction on JET and ASDEX upgrade

Improved ERO modelling of beryllium erosion at ITER upper first wall panel using JET-ILW and PISCES-B experience