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Boeuf J.-P.,CNRS LAPLACE Lab | Yang L.L.,Nanjing Southeast University | Pitchford L.C.,CNRS LAPLACE Lab
Journal of Physics D: Applied Physics | Year: 2013

It has been demonstrated experimentally that a non-equilibrium plasma column can be generated by discharge pulses in a helium jet surrounded by atmospheric-pressure air. The 'plasma jet' can be longer than 10 cm and fast imaging shows that most of the light emitted by the plasma jet is produced in a small 'plasma bullet' that propagates along the helium jet at speeds of several tens of km s-1. With the help of a simple fluid model of the discharge, we show that the plasma jet is very similar to a cathode streamer (ionization wave) guided by the helium jet. We discuss the properties of the helium streamer and of the plasma channel behind the streamer head as a function of parameters such as electrode geometry, voltage pulse waveform and preionization density. The model can reproduce qualitatively and explain most of the features observed experimentally. © 2013 IOP Publishing Ltd.

Lucia O.,University of Zaragoza | Maussion P.,CNRS LAPLACE Lab | Dede E.J.,University of Valencia | Burdio J.M.,University of Zaragoza
IEEE Transactions on Industrial Electronics | Year: 2014

Induction heating (IH) technology is nowadays the heating technology of choice in many industrial, domestic, and medical applications due to its advantages regarding efficiency, fast heating, safety, cleanness, and accurate control. Advances in key technologies, i.e., power electronics, control techniques, and magnetic component design, have allowed the development of highly reliable and cost-effective systems, making this technology readily available and ubiquitous. This paper reviews IH technology summarizing the main milestones in its development and analyzing the current state of art of IH systems in industrial, domestic, and medical applications, paying special attention to the key enabling technologies involved. Finally, an overview of future research trends and challenges is given, highlighting the promising future of IH technology. © 2013 IEEE.

Grodsky S.A.,University of Maryland University College | Reverdin G.,CNRS LAPLACE Lab | Carton J.A.,University of Maryland University College | Coles V.J.,University of Cambridge
Remote Sensing of Environment | Year: 2014

The fresh Amazon/Orinoco plume covers in excess of 106km2 in late summer-early fall forming a near-surface barrier layer that reduces exchange with the cooler, saltier water below. Barrier layers and higher water turbidity keep SST in the region high and thus are factors in the development of fall season hurricanes. Year to year changes in key properties of salinity and areal coverage may depend on a number of factors including river discharge, ocean rainfall, vertical entrainment rate, and horizontal advection. This study uses new sea surface salinity observations from the Aquarius/SACD and SMOS satellites to show that the plume was 1psu saltier in early fall 2012 than in the previous fall (despite a stronger Amazon discharge in 2012) and explores the possible causes. The study concludes that the most likely causes of the 2012 salinification are a relative deficit of rainfall over the inflow to the plume region well southeast of the plume in spring and a weaker North Brazil current in spring-summer. The results suggest that tracking spring rainfall can potentially contribute to forecasting the Amazon plume stratification during the fall hurricane season. © 2013 Elsevier Inc.

Li L.,University of Electronic Science and Technology of China | Lanteri S.,French Institute for Research in Computer Science and Automation | Perrussel R.,CNRS LAPLACE Lab
Journal of Computational Physics | Year: 2014

A Schwarz-type domain decomposition method is presented for the solution of the system of 3d time-harmonic Maxwell's equations. We introduce a hybridizable discontinuous Galerkin (HDG) scheme for the discretization of the problem based on a tetrahedrization of the computational domain. The discrete system of the HDG method on each subdomain is solved by an optimized sparse direct (LU factorization) solver. The solution of the interface system in the domain decomposition framework is accelerated by a Krylov subspace method. The formulation and the implementation of the resulting DD-HDG (Domain Decomposed-Hybridizable Discontinuous Galerkin) method are detailed. Numerical results show that the resulting DD-HDG solution strategy has an optimal convergence rate and can save both CPU time and memory cost compared to a classical upwind flux-based DD-DG (Domain Decomposed-Discontinuous Galerkin) approach. © 2013 Elsevier Inc.

Diaham S.,CNRS LAPLACE Lab | Locatelli M.-L.,CNRS LAPLACE Lab
Applied Physics Letters | Year: 2012

Space-charge-limited currents have been identified in thin polyimide film capacitor structures as the main conduction process in the very high temperature range from 320°C to 400°C before the breakdown. The transition field between the trap-filled-limit conduction and the trap-free conduction is reported versus temperature. Assuming an exponential distribution of the traps in the forbidden gap, both the characteristic temperature and trap energy are obtained at 446°C and 62meV, respectively. The total trap density is accurately estimated at 1.5×1017cm-3 using the Kumar approximation [Kumar, J. Appl. Phys. 94, 1283 (2003)]. Finally, the mobility temperature dependence of free charges is reported between 1.6×10 -6 and 2.3×10-6 cm2 V-1 s -1 in the range from 340°C to 400°C. © 2012 American Institute of Physics.

Cougo B.,CNRS LAPLACE Lab | Meynard T.,CNRS LAPLACE Lab | Gateau G.,CNRS LAPLACE Lab
IEEE Transactions on Power Electronics | Year: 2011

Parallel multilevel converters are now widely used in the industry, particularly in high-current applications such as voltage regulator modules. The reduction of the output current ripple and the increase of its frequency are possible due to the use of interleaving techniques and, as a consequence, the filters associated with the converter may be reduced. The current ripple reduction in each commutation cell of a parallel converter is possible by the use of intercell transformers (ICT). The design of such a special magnetic component depends very strongly on the magnetic flux flowing through their cores. In three-phase systems coupled by ICTs, the injection of zero-sequence signals in the output voltage reference changes this flux. The aim of this paper is to explain the influence of the most popular pulse width modulation (PWM) methods regarding the ICT flux for applications to three-phase loads. An optimal PWM method that minimizes the size of the ICT design is developed. Experimental results verify the analysis presented in this paper and validate the flux reduction provided by the developed optimal zero-sequence signals. © 2011 IEEE.

Boeuf J.-P.,National Polytechnic Institute of Toulouse | Boeuf J.-P.,CNRS LAPLACE Lab | Chaudhury B.,National Polytechnic Institute of Toulouse
Physical Review Letters | Year: 2013

The formation of a rotating instability associated with an ionization front ("rotating spoke") and driven by a cross-field current in a cylindrical magnetized plasma is shown and explained for the first time on the basis of a fully kinetic simulation. The rotating spoke is a strong double layer (electrostatic sheath) moving towards the higher potential region at a velocity close to the critical ionization velocity, a concept proposed by Alfvén in the context of the formation of the solar system. The mechanisms of cross-field electron transport induced by this instability are analyzed. © 2013 American Physical Society.

Unfer T.,National Polytechnic Institute of Toulouse | Unfer T.,CNRS LAPLACE Lab
Journal of Computational Physics | Year: 2013

This paper presents an asynchronous framework dedicated to the simulation of plasma discharges interacting or setting in motion the neutral gas. The method is based on Asynchronous Adaptive Mesh Refinement. Extensions of the asynchronous time integration to Runge Kutta method and centered schemes are given. The method is then applied to the simulation of the airflow generated by Surface Dielectric Barrier Discharges driven by sine or nanosecond pulses. © 2012 Elsevier Inc.

This paper has for objectives to present the radiative and the transport properties for people beginning in thermal plasmas. The first section will briefly recall the equations defined in numerical models applied to thermal plasmas; the second section will particularly deal with the estimation of radiative losses; the thirpart will quickly present the thermodynamics properties; and the last part will concern the transport coefficients (thermal conductivity, viscosity and electrical conductivity of the gas or mixtures of gases). We shall conclude the paper with a discussion about the validity of these results the lack of data for some specific applications, and some perspectives concerning these properties for non-equilibrium thermal plasmas. © 2015 Author(s).

Proceedings - ISIE 2011: 2011 IEEE International Symposium on Industrial Electronics | Year: 2011

This paper describes the main trends and future challenges of electrical networks embedded in more electrical aircraft especially in the fields of industrial electronics and energy conversion. In the first part, the current context and new standards are put forward, emphasizing the main evolutions on aircraft architectures, from AC fixed frequency networks, variable frequency to "Bleedless" architectures. The main characteristics of more electrical aircraft are discussed, especially in terms of power management rationalization, maintenance, health monitoring capacity, etc. The second part deals with the new trends and challenges of more and more electrical aircraft linked with power integration and new architecture with HVDC standard. Recent methodological orientations towards "Integrated Optimal Design"are discussed with representative examples. Finally, new trends towards reversible and hybrid HVDC networks including new storage devices are also emphasized. © 2011 IEEE.

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