Electromagnetic, complex image model of a large area RF resonant antenna as inductive plasma source

A large area antenna generates a plasma by both inductive and capacitive coupling; it is an electromagnetically coupled plasma source. In this work, experiments on a large area planar RF antenna source are interpreted in terms of a multi-conductor transmission line coupled to the plasma. This electromagnetic treatment includes mutual inductive coupling using the complex image method, and capacitive matrix coupling between all elements of the resonant network and the plasma. The model reproduces antenna input impedance measurements, with and without plasma, on a 1.2x1.2 m2 antenna used for large area plasma processing. Analytic expressions are given, and results are obtained by computation of the matrix solution. This method could be used to design planar inductive sources in general, by applying the termination impedances appropriate to each antenna type

La question du commissariat d’exposition

Paul-Louis Rinuy, entretien réalisé le 18 juin 2009 Q : L’œuvre d’art peut-elle se passer de commentaire ? P.L.R : Je ne pense pas que l’œuvre puisse se passer de commentaire car tout rapport à l’œuvre passe par une verbalisation, explicite ou implicite. Le commentaire utile, juste est celui qui prépare une rencontre expérimentale de l’œuvre. Et cette expérience de l’œuvre ne se réduit pas au commentaire. La question n’est donc pas : faut-il ou non un commentaire mais comment faire un bon ..

Helicon wave-generated plasmas for negative ion beams for fusion

In the next generation of fusion reactors, such as DEMO, neutral beam injectors (NBIs) of high energy (0.8-1 MeV) deuterium atom swith high wall-plug efficiency (>50%) will be required to reach burning plasma conditions and to provide a significant amount of current drive.The present NBI system for DEMO assumes that 50 MW is delivered to the plasma by 3 NBIs. In the Siphore NBI concept, negative deuterium ions are extracted from a long, thin ion source 3 m high and 15 cm wide, accelerated and subsequently photo-neutralized. This requires the development of a new generation of negative ion sources. At the Swiss Plasma Center, a novel radio frequency helicon plasma source, based on a resonant network antenna source delivering up to 10 kW at 13.56 MHz, has been developed and is presently under study on the Resonant Antenna Ion Device (RAID). RAID is a linear device (1.9 m total length, 0.4 m diameter) and is equipped with an extensive set of diagnostics for full plasma characterization. In this work, the principles of operation of resonant antennas as helicon sources areintroduced. Wepresent absolute spectroscopy, Langmuir probe, and interferometry measurements on helicon plasmas. We characterize the performanceof the source in terms of hydrogen/deuterium dissociation and negative ion production as a function of the input power. Furthermore, first results with the helicon birdcage antenna installed on the Cybele negative ion source at CEA-IRFM arepresented, as a first step towards the validation of the Siphoreconcept

Dual Langmuir-probe array for 3D plasma studies in TORPEX

We have designed and installed a new Langmuir-probe (LP) array diagnostic to determine basic three-dimensional (3D) features of plasmas in TORPEX. The diagnostic consists of two identical LP arrays, placed on opposite sides of the apparatus, which provide comprehensive coverage of the poloidal cross section at the two different toroidal locations. Cross correlation studies of signals from the arrays provide a basic way to extract 3D information from the plasmas, as experiments show. Moreover, the remarkable signal-to-noise performance of the front-end electronics allows us to follow a different approach in which we combine information from all probes in both arrays to reconstruct elementary 3D plasma structures at each acquisition time step. Then, through data analysis, we track the structures as they evolve in time. The LP arrays include a linear-motion mechanism that can displace radially the probes located on the low field side for experiments that require fine-tuning of the probe locations, and for operational compatibility with the recently installed in-vessel toroidal conductor

Modélisation de réseaux de distribution (DISGRID) comme outil d'étude prospectif de la combinaison de solutions de flexibilité à l'échelle transnationale

L’analyse des défis de fonctionnement des réseaux électriques dans un système à forte pénétration d’énergies renouvelables variables est un des enjeux principaux de leur décarbonation. Les réseaux électriques devront ainsi s’adapter à la nouvelle localisation des unités de production et à l’évolution des flux d’énergie. Ce papier présente la modélisation et l’analyse de réseaux de distribution électrique dans un couplage des modèles POLES et Backbone afin d’évaluer le rôle des réseaux de distribution dans la combinaison des solutions de flexibilité au sein d’une étude prospective du réseau électrique européen. Ce choix de granularité de modélisation permet une meilleure compréhension des dynamiques d’évolution des réseaux électriques. Une comparaison avec le modèle EUTGRID et les données réelles est utilisée pour montrer comment le modèle développé permet une réduction des temps de calcul et une précision intéressante

Impacts of the distribution grid on the European energy system prospective scenarios

To achieve decarbonization of the energy sector, the analysis of the power grid behavior under a high share of renewable energies is fundamental. However, in its current state, the electrical grid is not adapted to such a scenario due to volatile/uncertain profiles and limited hosting capacities in “weak” grid areas. Energy models and long-term prospective studies are needed to adapt the power grid to new paradigms and to reshape the grid and the electricity mix jointly considering the economic, technical, and environmental constraints

Splicing efficiency of minor introns in a mouse model of SMA predominantly depends on their branchpoint sequence and can involve the contribution of major spliceosome components

International audienceSpinal muscular atrophy (SMA) is a devastating neurodegenerative disease caused by reduced amounts of the ubiquitously expressed Survival of Motor Neuron (SMN) protein. In agreement with its crucial role in the biogenesis of spliceosomal snRNPs, SMN-deficiency is correlated to numerous splicing alterations in patient cells and various tissues of SMA mouse models. Among the snRNPs whose assembly is impacted by SMN-deficiency, those involved in the minor spliceosome are particularly affected. Importantly, splicing of several, but not all U12-dependent introns has been shown to be affected in different SMA models. Here, we have investigated the molecular determinants of this differential splicing in spinal cords from SMA mice. We show that the branchpoint sequence (BPS) is a key element controlling splicing efficiency of minor introns. Unexpectedly, splicing of several minor introns with suboptimal BPS is not affected in SMA mice. Using in vitro splicing experiments and oligonucleotides targeting minor or major snRNAs, we show for the first time that splicing of these introns involves both the minor and major machineries. Our results strongly suggest that splicing of a subset of minor introns is not affected in SMA mice because components of the major spliceosome compensate for the loss of minor splicing activity