Publications de Jean-Marc Moret

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Kinetic equilibrium reconstruction (KER) in tokamaks is the solution of the free-boundary MHD equilibrium that best fits the external magnetic measurements and the internal plasma profiles as imposed from modeling and/or available internal measurements. In ...

Resonant magnetic perturbation (RMP) and error field correction (EFC) produced by toroidally and poloidally distributed coil systems can be optimized if each coil is powered with an independent power supply. A 3D multi-mode geometry-independent Lagrange me ...

Research into neural networks has gained a large following in recent years. In spite of the long term timescale of this Artificial Intelligence research, the tools which the community is developing can already find useful applications to real practical problems in experimental research. One of the main advantages of the parallel algorithms being developed in Al is the structural simplicity of the required hardware implementation, and the simple nature of the calculations involved. This makes these technique

Confinement in TCV electron cyclotron heated discharges was studied as a function of plasma shape, i.e. as a function of elongation, 1.1 < kappa < 2.15, and triangularity, -0.65 less than or equal to delta less than or equal to 0.55. The electron energy confinement time was found to increase with elongation, owing in part to the increase of plasma current with elongation. The beneficial effect of negative triangularities was most effective at low power and tended to decrease at the higher powers used. The l

The TCV tokamak has obtained ohmic H-modes in virtually all diverted plasmas with the ion del B drift directed towards an X-point and in several elongated limiter plasmas. Troyon factors (beta(tor)aB/l(p)) up to 2 and line average densities up to 2.2 x 10(20) m(-3), corresponding to the Greenwald limit, have been obtained in diverted ELM-free H-modes. Quasi-stationary H-modes lasting for the entire current flat top (1.5 s) have been obtained in the presence of regular ELMs. The occurrence and magnitude of E

The analysis and interpretation of perturbative modulated electron cyclotron heating (MECH) discharges for power deposition localization using different diagnostics, such as electron cyclotron emission (ECE) and soft x-ray (SXR) measurements, are presented. In particular, the experimental determination of the MECH power deposition is investigated, which is a fundamental requirement, for example, for heat transport studies. The most important problem is related to the coupling between the MECH and the sawtoo

Alfven eigenmodes and other magnetohydrodynamic phenomena have been studied in tokamak plasmas at the Joint European Torus (JET) using a new eight-channel, 4 s, 1 MHz, 12-bit data acquisition system (KC1F) in conjunction with the JET fast Mirnov magnetic fluctuation pickup coils. To this end, the JET magnetic pickup coils were calibrated in the range 30-460 kHz using a new remote calibration technique which accounts for the presence of the first few LRC circuit resonances. Signal processing software has bee

The measurement performance of the baseline system design for the ITER high-frequency magnetic diagnostic has been analyzed using an algorithm based on the sparse representation of signals. This algorithm, derived from the SparSpec code [S.Bourguignon et a ...

Measurement of the plasma generated diamagnetic flux on tokamak a configuration variable (TCV) is used to derive the plasma pressure, as on other magnetic confinement experiments. However, specificities of the device make the measurement more difficult: for passive stabilization of the vertical position of highly elongated plasmas, the vessel has a low electrical resistivity, leading to large image currents in the vessel. For the same reason the plasma must also be kept close to the conducting wall, so that

The TCV tokamak (R = 0.88 in, a < 0.25 in, BT < 1.54 T) is equipped with six 0.5 MW gyrotron sources operating at 82.7 GHz for second harmonic X mode ECH. By distributing the ECCD current sources over the discharge cross section, fully driven stationary plasmas with I-p = 210 kA, n(e0) = 2 x 10(19) m(-3), T-e0 approximate to 4 keV, were obtained for the full discharge duration of 2 s. Highly peaked electron temperature profiles with T-e0 up to 12 keV were obtained in central counter-current drive scenarios

The stability of the vertical position control system in TCV is analysed using two different plasma models, a deformable plasma model (DPM) and a rigid plasma model (RPM). The open loop growth rates and closed loop stability are computed, as functions of various plasma parameters, for both models. It is found that the difference between the open loop growth rates predicted by the two models depends significantly on plasma elongation and triangularity. Growth rates are also computed using the NOVA-W code, an

A new paradigm is presented to reconstruct the plasma current density profile in a tokamak in real-time. The traditional method of basing the reconstruction on real-time diagnostics combined with a real-time Grad-Shafranov solver suffers from the difficult ...

Magnetic diagnostics are essential for the operation and understanding of a magnetic fusion device. Magnetic data are used in real time to measure and control the current, shape, and position of the discharge; the thermal energy of the plasma; the confinin ...

The operating space of the TCV tokamak has been extended to higher elongation, kappa = 2.8, and higher normalized current, I-N = I-p/aB = 3.6MA/mT, than were previously attainable. This has been achieved by optimizing the parameters of the vertical position control system and by optimizing the plasma shape. Experimental current and beta limits were found to be consistent with ideal MHD stability calculations, using measured plasma shapes and profiles. The sawtooth period was measured as a function of elonga

The measurement performance of the baseline system design for the ITER high-frequency magnetic diagnostic system and attempts at its optimization have been performed using an innovative method based on the sparse representation of signals and the minimizat ...

The TCV tokamak (B-T < 1.5 T, R approximate to 0.88 m, a < 0.25 m) has produced a wide variety of plasma configurations, both diverted and limited, with elongations kappa(a), ranging from 0.9 to 2.58, triangularities delta(a) from -0.7 to 1 as well as discharges with nearly rectangular cross sections. Plasma currents of 1 MA have been obtained in elongated discharges (kappa(a) approximate to 2.3). Ohmic discharges with delta(a) < 0 have smaller sawteeth and higher levels of MHD mode activity than plasmas wi

In the first results of electron Bernstein wave heating (EBWH) via O-X-B double mode conversion in a medium aspect ratio tokamak performed in TCV, the total power absorption efficiency was typically 60% and the deposition was made off-axis to avoid the central sawteeth perturbation that would prevent a clear detection of the deposition location. Central power deposition is however needed to maximize the global EBWH effects. Therefore, initial experiments have been started to optimize central deposition usin

Starting from a standard single null X-point configuration, a second order null divertor (snowflake (SF)) has been successfully created on the Tokamak à Configuration Variable (TCV) tokamak. The magnetic properties of this innovative configuration have bee ...

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 a previous paper, a Self-Organizing Map had proven to be able to identify the regions of the plasma operative space characterizing the pre-disruptive phase at JET without relying on any a priori information. One of the strengths of this disruption predictor lies in its inherent self-organization capability. The Self-Organizing Map discovers non-trivial relationships and captures the complicated interplay of device diagnostics on the internal plasma states directly from the experimental data. Moreover, th

Jean-Marc Moret

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First demonstration of real-time kinetic equilibrium reconstruction on TCV by coupling LIUQE and RAPTOR

A 3D multi-mode geometry-independent RMP optimization method and its application to TCV

Neural Networks in Front-End Processing and Control

Energy confinement and MHD activity in shaped TCV plasmas with localized electron cyclotron heating

Ohmic H-modes in the TCV tokamak

Signal processing techniques based on singular value decomposition applied to modulated ECH experiments

Fast magnetic fluctuation diagnostics for Alfven eigenmode and magnetohydrodynamics studies at the Joint European Torus

Functional Performance Analysis and Optimization for the High-Frequency Magnetic Diagnostic System in ITER - I: Overview of the Results

Fast single loop diamagnetic measurements on the TCV tokamak

Overview of TCV results

Stability analysis of the vertical position control loop in TCV using rigid and deformable plasma models

Real-time physics-model-based simulation of the current density profile in tokamak plasmas

Magnetic Diagnostics

Stability and energy confinement of highly elongated plasmas in TCV

Functional Performance Analysis and Optimization for the High-Frequency Magnetic Diagnostic System in ITER - II: Detailed Overview of the Analysis Method and of the Test Calculations

Effect of plasma shape on confinement and MHD behaviour in TCV

Electron Bernstein Wave Core Deposition via O-X-B Double Mode Conversion in TCV

Snowflake Divertor Plasmas on TCV

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

A procedure for rule extraction from a Self-Organising plasma disruption predictor for JET