Publications by Bertrand Dutoit

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The adjunction of constrictions along the meander of a superconducting Fault Current Limiter (FCL) greatly improves its behavior thanks to a better distribution of the dissipative zones at the occurrence of a short circuit. This design works perfectly for ...

The use of carbon ions in particle therapy can enhance the treatment quality, introducing higher biological effectiveness compared to photons and protons. Rotating gantries are nowadays used to deliver particle beams from different directions to obtain pre ...

Superconducting fault current limiters (SFCLs) can be used to limit fault currents in both meshed DC and AC grids by transitioning from superconducting to resistive state, in the presence of high currents. While the device is theoretically a great way to p ...

This paper describes quantitatively the magnetic field inside the windings of a HTS transformer. The results are obtained by means of finite element method simulations, using the electromagnetic software package Flux2D. The transformer design has been made by ŠKODA in the European project BIG-POWA. The ratings of the transformer are U1 = 400 V, I1 = 47 A, U2 = 133 V, I2 = 140 A (rms values). The magnetic field in the superconducting windings has been calculated in the steady state regime at 50 Hz. It is non

Different measurement techniques have demonstrated that due to better alignment during the manufacturing process, the central filaments in multifilamentary Bi-2223 tapes have higher critical current density than the outer filaments. A numerical model of non-twisted tapes has been used in Finite-Element-Method simulations. The model incorporates non-uniform lateral Jc distribution in accordance with direct Ic measurements, made along the width of a Bi-2223 tape. Two types of simulations are performed on 7 an

This paper presents results from numerical modelling of BSCCO conductors performed with finite element method software. The AC losses are calculated and compared for conductors of different geometry and aspect ratio – an elliptical tape with anisotropic Jc(B) and a round wire with isotropic Jc(B), in external magnetic field of various angles. The difference in the losses of the wire and the tape is found to be significant and depends on the applied field’s magnitude and orientation. Studied is also the effe

Using 3D finite element method (FEM) modelling, the present work investigates the coupling effect between two finite superconductors through a resistive matrix. This effect, related to the finite length of the conductors, is typically three-dimensional and cannot be analyzed by the widely utilized 2D models. Superconductors are modelled with the non linear power law E=Ec(J/Jc)^n, which has been implemented in the FEM software. The main focus is to demonstrate the feasibility of such calculations and to esta

The engineering critical current (Ic) of the high temperature superconducting coated conductors (HTS-CCs), today available on the market, is not a uniform parameter and varies significantly along the length of the conductors. Moreover, commercial HTS-CCs h ...

The classic Preisach model is used to describe a general hysteretic behaviour, and as most nonlinear systems, its output contains higher harmonics. A Fourier analysis of a specific class of weighting functions for the Preisach model relates some free parameters with the frequency contents of the output. This enables an identification of the parameters from higher harmonics, by which hysteretic losses can be separated from losses in linear elements.

We present an experimental study of the current induced destruction of superconductivity in films of type-1 superconductors. The most interesting aspect of these experiments is the possibility to observe and investigate different mechanisms of the superconductivity destruction depending on the ratio of the sample thickness d to the coherence length xi(T). If d/xi(T) < 4.5 we observe, above a critical current value, a resistive state throughout the section of the film, but in the case of d/xi(T) > 4.5 the de

The use of HTSC tapes as main components in future power applications requires better understanding of their AC loss behaviour. Previous studies have lead to conclusions that eddy current loss is a significant loss factor at high frequency in self-field. In this paper we present a Finite Elements Method electromagnetic simulation of the current density and magnetic field distribution in the tape for 59Hz and 1kHz. The Ac losses due to eddy currents in the silver sheath are calculated for a mono and multicor

We present an experimental study of the current induced destruction of superconductivity in cylindrical indium films. The most interesting aspect of these experiments is the possibility to observe and investigate different mechanisms of the superconductivity destruction depending on the ratio of the sample thickness d to the coherence length xi(T). If d/xi(T)4.5 the destruction o

We present the results of an advanced numerical model for fault current limiter (FCL) based on HTS thin films in which both thermal and electromagnetic aspects are taken into account. This model allows simulating the behavior of FCL in the over-critical cu ...

Understanding the electro-thermal behavior of high-temperature superconductor (HTS) materials is a critical aspect for designing efficient and reliable applications. In order to optimize cost and performance, one needs to understand the role played by the ...

Study of the quench phenomenon is crucial for the design of Resistive Fault Current Limiters (RFCLs) based on high temperature superconducting coated conductors (HTS-CCs). An optimal stabilization of the tape is required to achieve both an economic device and a safe quench. In this context we developed an electro-thermal model that describe the HTS-CCs quench behavior for different degrees of inhomogeneity, both in terms of critical current and of thickness stabilizer. The critical current inhomogeneity for

This paper describes quantitatively the influence of the self-field and the cross-sectional geometry on the effective critical current and the ac losses in transport current applications of non-twisted multifilamentary Bi-2223/Ag conductors. The results are obtained with finite element method simulations. The numerical implementation includes an anisotropic model for the dependence of the critical current density Jc and the power index n on the local parallel and perpendicular magnetic field components. The

An identification method for Preisach-type models of hysteresis is presented. By using a phenomenological Preisach-type model for hysteresis we can obtain an exact model for the magnetisation hysteresis in the cases of tapes with strip and with elliptical cross section geometries. With a parametrisation by Maclaurin series, it is possible to identify such a model for any other geometry. An additional advantage of this method is that the parameters are identified from the measurements of energy losses per cy

We present an experimental study of the current induced destruction of superconductivity in thick cylindrical indium films. The most interesting aspect of these experiments is the possibility to observe and investigate different mechanisms of the superconductivity destruction depending on the ratio of the sample thickness d to the coherence length xi(T). If d/xi(T)4.5 the destruction of superconductivity starte

The electrical resistivity of coated conductors is strongly related to the inter-dependent set of parameters (J, H, T), respectively current density, magnetic field and temperature. On the one hand, it is difficult to isolate the contribution of each of th ...

We have made a software electromagnetic simulation of eddy current effects in Bi(2223)Ag sheathed tapes with applied AC transport current in a broad frequency range. We have used simple models of monocore and multicore tapes. Calculated is the power distribution (W/m3) within the metal sheath using the geometry of real tapes. The numerical simulation is carried out with Finite-element-method software. The paper also describes the influence of the tape cross-sectional architecture and the sheath resistivity

Bertrand Dutoit

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Thermally Assisted Transition in Thin Film Based FCL: A Way to Speed Up the Normal Transition Across the Wafer

Feasibility Study of GaToroid Gantries for Carbon Ions

Fast Hotspot Detection in SFCLs by Exploiting Strain Response in Optical Fiber Sensing

Modelling the magnetic field effects in a high-Tc superconducting transformer

Numerical modelling of Bi-2223 multifilamentary tapes with position-dependent Jc

Modelling of BSCCO conductors with anisotropic and position-dependent Jc

Finite element method analysis of the coupling effect between superconducting filaments of different aspect ratio

Impact of the Normal Zone Propagations Velocity of High Temperature Superconducting Coated Conductors on Resistive Fault Current Limiters

Preisach model identification from higher harmonics

Current-Induced Resistive State in Cylindrical Superconducting Films .2. 2-Dimensional Mixed-State of Type-1 Superconductors

Magnetic and electric simulation of eddy currents in Ag sheathed Bi2223 tapes

Current-Induced Resistive States in Superconducting Films

Computer Modeling of YBCO Fault Current Limiter Strips Lines in Over-Critical Regime With Temperature Dependent Parameters

Overcritical Current Resistivity of YBCO-Coated Conductors Through Combination of PCM and Finite-Element Analysis

Modelling of the quench behaviour of HTS-CCs for RFCLs

Self-field and geometry effects in transport current applications of multifilamentary Bi-2223/Ag conductors

Preisach-type hysteresis modelling in Bi-2223 tapes

Current-Induced Resistive States in Superconducting Films

Evaluation of the Applicability of Phenomenological HTS Models for Numerical Analysis of Quenches in Coated Conductors: Simulations vs. Experiments

Effect of the sheath resistivity and tape geometry on eddy current loss in Bi(2223) tapes