Publications de Jean-Marc Moret

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Analysis of magnetic fluctuations is important for understanding the magneto-hydrodynamic (MHD) properties of fusion plasmas. These properties affect nearly all aspects of behaviour of magnetic confinement, and thus are of interest in topics ranging from global plasma stability, control, and disruption avoidance, to more subtle areas such as MHD spectroscopy. Mode number analysis is generally accomplished by interpreting signals from a finite number of Mirnov coils, which typically are unevenly spaced in th

The original TCV control system was designed in the late 1980s to be inherently network based in that all control operations were performed from X-windows terminals and the control computers were networked. Using VMS-VAX technology, the acquisition system (CAMAC) and control system (BITBUS) were connected to controllers situated in the machine bus of these machines that were linked homogeneously by the VMS 'cluster' technology. Although the computing power and network bandwidth have improved considerably ov

Improvement in the performance of magnetic confinement devices for nuclear fusion relies on the optimization of the geometry of the plasma: either the two-dimensional (2D) cross-section shape in tokamaks with toroidal symmetry or the 3D magnetic configurat ...

Fusion power is the most significant prospects in the long-term future of energy in the sense that it composes a potentially clean, cheap, and unlimited power source that would substitute the widespread traditional nonrenewable energies, reducing the geogr ...

Magnetic diagnostics for the new generation fusion reactor “ITER” are required to be extremely reliable since they provide measurements essential for reactor operation and protection, plasma control and for measurement of several parameters fundamental to ...

Fusion power may be seen as the energy of the future in the sense that it composes a potentially clean, cheap and unlimited power source that would reduce the worldwide dependency on non-renewable energies. Nevertheless, while nowadays the fusion reaction ...

Recent Lower Hybrid Current Drive (LHCD) experiments in TORE SUPRA and JET are reported. Large multijunction launchers have allowed the coupling of 5 MW to the plasma for several seconds with a maximum of 3.8 kw/cm2. Measurements of the scattering matrices of the antennae show good agreement with theory. The current drive efficiency in TORE SUPRA is about 0.2 x 10(20) Am-2/W with LH power alone and reaches 0.4 x 10(20) Am-2/W in JET thanks to a high volume-averaged electron temperature (1.9 keV) and also to

The high-frequency (HF) magnetic sensors for ITER are currently based on a conventional, Mirnov-type, pick-up coil, with an effective area in the range 0.03

This contribution describes the results of impurity seeding experiments using neon gas injection into the private fl zone of an ohmically heated TCV single null lower, deuterium fuelled, open divertor configuration. In these first experiments, neon has been injected under feedback control on the intensity of the UV NeVIII line at 77 nm. Measurements of the dependence of edge temperature and density on ii, at the outboard divertor target show the divertor in the absence of neon to be operating in the low rec

The most efficient and promising operational regime for the International Thermonuclear Experimental Reactor tokamak is the high-confinement mode. In this regime, however, periodic relaxations of the plasma edge can occur. These edge-localized modes pose a ...

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 ...

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

The ITER high-frequency (HF) magnetic sensor is currently intended to be a conventional, Mirnov-type, pickup coil, designed to provide measurements of magnetic instabilities with magnitude as low as |dB|~10e-4G at the position of the sensors and up to freq ...

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 TCV Tokamak was designed to create a large variety of plasma shapes. Such a large flexibility requires high precision magnetic measurements with a good spatial coverage. This article gives a detailed description of the magnetic sensor geometry, fabrication, calibration, the associated electronics, and the diagnostic operation and monitoring. A substantial effort has been made to quantify the precision in the measurements and a novel method has been developed to derive corrections in the sensor position

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

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

The additional power absorbed by the plasma can be determined from the time derivative of the total plasma energy, which can be estimated from the diamagnetic flux of the plasma using a diamagnetic loop. The main difficulty in using diamagnetic measurements to estimate the kinetic energy is the compensation of the flux measurement sensitivity to poloidal magnetic fields, which is not always easy to adjust. A method based on the temporal variations of the diamagnetic flux of the plasma during modulated elect

The large variety of plasma shapes produced in the TCV tokamak places unique demands on the plasma facing surfaces. In particular, the central column graphite armour tiles are solicited during the creation of all TCV plasmas and function as power handling surfaces for both limited and diverted discharges. The higher power flux densities accompanying the addition of electron cyclotron heating systems have necessitated a new, optimized, design for these tiles. The optimization process and the subsequent new t

Jean-Marc Moret

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Astrophysics and Fusion Plasmas: application of the SparSpec algorithm to the data analysis and design of the ITER high-frequency Mirnov coil diagnostic system

Evolution not revolution in the TCV tokamak control and acquisition system

A software package to manipulate space dependencies and geometry in magnetic confinement fusion

A Variable Structure Control Scheme Proposal for the Tokamak a Configuration Variable

3D Thermal and CFD Simulations of the Divertor Magnetic Coils for ITER

Sliding Surface Based Schemes for the Tokamak a Configuration Variable

Lower Hybrid Current Drive in Tore Supra and Jet

Prototyping Conventionally Wound High-Frequency Magnetic Sensors for ITER

Experimental investigation of the effects of neon injection in TCV

Effect of energetic ions on edge-localized modes in tokamak plasmas

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

Safety factor profile requirements for electron ITB formation in TCV

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

Prototyping a High-Frequency Inductive Magnetic Sensor Using the Nonconventional, Low-Temperature Co-Fired Ceramic Technology for Use in ITER

ECH physics and new operational regimes on TCV

Magnetic measurements on the TCV Tokamak

A saddle coil system for TCV and RMP spectrum optimisation

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

Modulated ECH power absorption measurements using a diamagnetic loop in the TCV tokamak

The design of central column protection tiles for the TCV tokamak