The present work concerns the study of pulsed laser systems containing a fiber amplifier for boosting optical output power. In this paper, this fiber amplification device is included into a MOPFA laser, a master oscillator coupled with fiber amplifier, usually a cladding-pumped high-power amplifier often based on an ytterbium-doped fiber. An experimental study has established that the observed nonlinear effects (such as Kerr effect, four waves mixing, Raman effect) could behave very differently depending on the characteristics of the optical source emitted by the master laser. However, it has not yet been possible to determine from the experimental data if the statistics of the photons is alone responsible for the various nonlinear scenarios observed. Therefore, we have developed a numerical simulation software for solving the generalized nonlinear Schrödinger equation with a stochastic source term in order to validate the hypothesis that the coherence properties of the master laser are mainly liable for the behavior of the observed nonlinear effects.

The main form of electrical discharge in long air gaps is broken down by leader mechanism. The leader development in rod-rod gaps under positive switching impulse was investigated by using two high-speed CCD cameras. The clearer and more particular colorized physical morphology of the leader propagation process than the traditional image converter cameras was recorded and the leader development parameters were also obtained. As a comparative study, an improved simplified model for rod-rod configuration was performed to simulate the leader development. The numerical simulations of leader development characteristics were in a close agreement with that of experimental measurements.

In particle accelerators, the bending magnets have to be wound with flared ends. This particular shape induces an inhomogeneity in the magnetic field in the ends, which degrades the particle beam stability. This paper proposes a 3D modeling for conductors with rectangular cross-sections. The coil is first divided into blocks (parallelepipeds and arcs). Then the magnetic field is evaluated in every point of space by means of analytical formulas which allow an accurate computation. This method is also faster than numerical integrations of Biot and Savart law. Some optimization examples are finally presented and show that it is possible to minimize, with a few degrees of freedom only, the first field harmonics, integrated along the beam tube.

This paper proposes a design approach of an electrical power supply intended to offer an especially well-suited supply mode, through the efficient control of the current injected into a DBD setup. The proposed topology is aimed at controlling the operating point of the electrical discharge, thereby allowing favoring the homogeneous regime, and maximizing the electrical power injected into the plasma. The power supply structure is designed on the basis of causality criteria and of an analytical analysis of the electrical waveforms, which are derived from an equivalent circuit model of the DBD. Design issues of this electrical generator are detailed and experimental analysis of its operation, together with actual performances are presented. A very good agreement is obtained by comparing simulation and experiments. Effective ability to control the power transfers by means of its two degrees of freedom (current magnitude and frequency) is highlighted.

This article presents an explicit model of electromagnetic (EM) coupling between electronic circuits and metallic wire placed above the ground plane. The model is based on the interaction between the EM near-field (NF) that has been treated with plane wave spectrum (PWS) and the Taylor model. The routine process illustrating the methodology is addressed is this article. The practicability of the model developed was upheld with different analytical and real demonstrators. First, the NF coupling between a straight transmission line (TL) and 1 GHz Wilkinson power divider (PWD) designed and implemented in planar technology was provided. Subsequently, simulations with a powerful commercial tool and measurements from 0.2 GHz to 2 GHz revealed a good agreement between the coupling voltages from the proposed model. As a second proof of concept, a printed circuit board incorporating a 40 MHz RF oscillator was placed 5 mm above the grounded TL. Once again, coupling voltages matched measurements were observed with magnitude relative difference lower than 5 dB. The hereby model presents huge benefits not only in terms of flexibility in the design process but it can also be run with very less computation time compared to the existing standard simulators. The model can be potentially a good candidate for investigating complex systems EMC engineering.

This article presents a time domain discontinuous Galerkin method applied for solving the con-servative form of Maxwells’ equations and computing the radiated fields in electromagnetic compatibility problems. The results obtained in homogeneous media for the transverse magnetic waves are validated in two cases. We compare our solution to an analytical solution of Maxwells’ equations based on characteristic method. Our results on shielding effectiveness of a conducting wall are same as those obtained from analytical expression in frequency domain. The propagation in heterogeneous medium is explored. The shielding effectiveness of a composite wall partially filled by circular conductives inclusions is computed. The proposed results are in conformity with the classical predictive homogenization rules.

Accurate monitoring of energy consumption is key for electrical energy management in industry This implies the use of low-cost and easy-to-install measuring chains that can be placed directly around three-phase cables without interrupting power delivery. This paper describes an innovative current measurement method using a magnetic sensor array dispatched around three-conductor cables. Analytical solution is given for the measurement problem and results from simulations.

Non-destructive testing of heritage mural paintings by means of stimulated infrared thermography has now become rather efficient [1–14]. However, pigments, which form a pictorial layer, have contrasting radiative properties possibly leading to artifact detection. In this paper, attempts to alleviate this difficulty are presented. Based on the spectroscopic study of different paint layers, one can argue that, in the medium infrared field, this radiative disparity decreases significantly. Then, with similar settings, it can be shown that ceramic radiative sources allow reaching this wavelength band. Finally, on the basis of a study carried out on an academic sample and a partial copy of a fresco from the cathedral of Angers, combining ceramic heat sources with a laboratory SAMMTHIR experimental setup enables to make real headway in terms of defects’ detection.

In this paper an approach for the modeling of the eddy current testing of a conductive part with flat printed coils is proposed. The overlapping finite element method is implemented for this purpose. It is shown that this approach allows simplifying the modeling of eddy current testing configurations that use this kind of coil.

Semi-analytical models developed at Cea List for the simulation of Eddy current non-destructive testing are currently based on the volume integral equation formalism. This method is very effective for canonical geometries such as planes or cylinders since the analytical expressions of Green’s dyads are known. This approach requires three steps: the computation of the quasi-static fields induced by the probe in the workpiece without flaw, the determination of the interaction between the primary field and the defect and finally, the calculation of the response of the eddy current sensor, resulting from this interaction. In order to generalize this approach to more complex configurations, in this paper, we focus on the first step: the computation of quasi-static fields induced by an eddy current probe in a conductor with a rough surface. The semi-analytical model we generalize here is based on Maxwell’s equations, written in a non-orthogonal coordinate system resulting in the writing of the boundary conditions at the interface by using a simple analytical expression. Starting from the second-order vector-potential formalism dedicated to non-orthogonal curvilinear coordinate systems, two scalar potentials are expressed as a modal expansion, satisfying the outgoing wave condition. Finally, the coefficients of the modal expansion are determined by applying boundary conditions at the complex interface. First numerical results, obtained considering a specific configuration, are compared to other Finite Element data.

A double-layered membrane model is proposed to explain raft formation and induction on extracellular (outer) and cytoplasmic (inner) leaflets of plasma membranes in a situation where only the outer layer has a tendency to phase-separate. In the model, lipid exchange with the surrounding medium is allowed on both layers, but lipid exchange between layers is not allowed. Simulations display domain stabilization on both layers. The effect of the lipid recycling frequencies on stationary domain sizes is also investigated. It is found that stationary domain sizes decrease when lipid recycling frequencies are stronger. Linear stability analysis is used to verify the results.

This paper proposes a criterion for locating obstacles by time reversal (TR) of electromagnetic (EM) waves based on the analysis of the density of EM energy map in time domain. Contrarily to a monochromatic study of the TR, the wide-band approach requires to determine the instant of the wave focus. This enables us to locate the focal spots that are indicative of the positions. The criterion proposed is compared to the inverse of the minimum entropy criterion as used in the literature [X. Xu, E.L. Miller, C.M. Rappaport, IEEE Trans. Geosci. Remote Sens. 41, 1804 (2003)]. An application for the localization of 3D metal targets is proposed using finite integration technique (FIT) as computational tool at the modeling stage. An experimental validation is presented for canonical three-dimensional configurations with two kinds of metal objects.

The morphological parameter of a thin film surface can be characterized by power spectral density (PSD) function which provides a better description on topography rather than the root mean square (RMS) and super structure contributions. Through the present study, nanoparticle copper-carbon composite films were prepared by co-deposition of RF-sputtering and RF-PECVD method using acetylene gas and copper target. These films’ surface roughnesses were determined by using an atomic force microscope (AFM). The carbon content of the films was obtained by Rutherford back scattering (RBS) which was varied from 5% to 73%. The power values of PSD for the AFM data were determined by the fast Fourier transform (FFT) algorithms. The effect of carbon on the surface roughness of thin films was investigated. Changes in the relationship between the resistivity and fractal dimension were observed for investigating films.

In order to model thin conductive non-magnetic shells, an original surface integral formulation is proposed. The method is based on a surface impedance condition which takes into account the field variation through depth due to skin effect. It is general and enables the modeling of various problems whatever their skin depth and avoiding the meshing of the air region. The formulation is compared with another integral formulation recently proposed by authors and is validated thanks to an axisymmetric finite-element method (FEM). Advantages and drawbacks of this new formulation are discussed.

In order to reduce the computation time of a quasi-static problem solved by the finite element method, methods of model order reduction can be applied. In this context, two approaches, the proper orthogonal decomposition and the proper generalized decomposition, are applied to the vector poten-tial formulation used to solve the quasi-static problem. The developed methods are compared on an academic example.

This paper calculates the electric and magnetic fields and the Poynting vector around two infinitely long parallel cylindrical conductors, carrying a DC current. Also the charges on the surface of the wire are calculated, and their distribution is visualized. The wire is assumed to be perfectly electrically conducting. Furthermore, the Hall effect is ignored. In the literature [S.J. Orfanidis, Electromagnetic waves and antennas, 2008], the problem of determining the electric field is usually tackled using an equivalent model consisting of two line charge densities, producing the same electric field. In this work, the Laplace equation is rigorously solved. The authors found no work explaining the solution of the Laplace equation with boundary conditions for this problem and hence thought it was useful to dedicate a paper to this topic. The method of separation of variables is employed and a bipolar coordinate system is used. After solving the appropriate Sturm-Liouville problems, the scalar potential is obtained. Taking the gradient yields the electric field.

A subproblem h-conformal eddy current finite element method is proposed for correcting the inaccuracies inherent to thin shell models. Such models replace volume thin regions by surfaces but neglect border effects in the vicinity of their edges and corners. The developed surface-to-volume correction problem is defined as a step of the multiple subproblems that can split a complete problem, consisting of inductors and magnetic or conducting regions, some of these being thin regions. The general case of multiply connected thin regions is considered.

This paper presents 2D and 3D homogenization techniques for laminated iron cores in the frequency domain. In 2D, two approaches (analytical and numerical) are compared in terms of complex reluctivity considering tangential magnetic field to laminations. The analytical approach is generalized to 3D problems. The validation performed on homogenized block gives satisfactory results only in case of closed-core or thin air gap open-core. Thus, we have a correct approximation only when the magnetic field is essentially parallel to laminations. In order to remediate the poor approximation of losses due to non parallel magnetic field component and model large air gap devices, we propose an alternative to block homogenization. A validation is done on a laminated open-core inductance.