Conducteur (électricité)

Résumé

Un conducteur d'électricité est un corps capable de laisser passer un courant électrique. Souvent, un bon conducteur d’électricité est aussi un bon conducteur de la chaleur. À l'opposé, un isolant électrique est un corps qui ne laisse pas passer le courant électrique. Un isolant est souvent également un mauvais conducteur de chaleur. thumb|Conducteurs électriques en cuivre entourés de leur isolant en plastique blanc. Matériaux conducteurs Plusieurs types de matériaux sont de très bons conducteurs :

généralement, les métaux sont conducteurs d’électricité, les meilleurs étant l'argent, le cuivre et l'or, mais du fait de leur prix, l'argent et l'or sont rarement utilisés comme conducteurs d’électricité. Cependant en informatique et en électronique l'or est utilisé, en couche mince, pour recouvrir et protéger de la corrosion les conducteurs en cuivre ou en argent des circuits imprimés ainsi que leurs connecteurs (ce qui permet de supprimer les résistances d

Source officielle

https://fr.wikipedia.org/wiki/Conducteur_(%C3%A9lectricit%C3%A9)

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The topics covered by the course are concepts of fluid mechanics, waves, and electromagnetism.

Comprendre les principes physiques utilisés dans les capteurs. Vue générale des différents principes de transduction et de l'électronique associée. Montrer des exemples d'application.

This course covers the metallurgy, processing and properties of modern high-performance metals and alloys (e.g. advanced steels, Ni-base, Ti-base, High Entropy Alloys etc.). In addition, the principles of computational alloy design as well as approaches for a sustainable metallurgy will be addressed

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The aim of this thesis is to investigate the mechanical and thermal behaviour of HTS coated conductor cables for EUROfusion DEMO magnets.One of the issue in large HTS magnets is the safety against a quench. A quench is a sudden thermal runway in which the energy stored in the magnet is turned into heat in a localized volume of the magnet. If no countermeasures are applied, the localized temperature increment might damage the magnet. A Quench Experiment has been carried out to provide experimental data on the full quench evolution in sub-size HTS cables for fusion application. The SULTAN facility has been upgraded. This upgrade allows us to provide large power to the conductor for indefinite time. Previously, the maximum power was limited to few W for few seconds. Four different sub-size conductors designed for the Central Solenoid magnet of EU DEMO have been fabricated with REBCO coated conductors. All the cables are based on a triplet of round strands, each strand is composed of two half-round copper profiles surrounding a stack of tapes. The copper profiles and the tapes are soldered together. The triplet is insert in steel jacket to obtain forced-flow conductors. The quench is triggered by sending hot helium in the conductor and the temperature evolutions of the conductor components (jacket, helium) have been measured up to temperatures of 150 K. Due to the gradients between cable, He and jacket, the maximum estimated temperature value on the cable is above 200 K, depending on the specific cable design. The experimental results of the different conductors have been interpreted with the support of a multi-physics code (THEA). It has been seen that decreasing the transverse thermal resistance between strand and jacket of one order of magnitude leads to a decrease in the temperature rise rate from tens of K/S to just few K/s: the heat produced in the cable can be better absorbed by the large thermal inertia of the jacket. The he multi-physics model indicates that, in case of the quench is caused by hot helium flow, the voltage rises much faster in case of homogenous magnetic field, leading to a lower hot spot temperature at the quench detection.The combination of large current and high magnetic field results in very large transverse stress on the cable. The superconducting ceramic material is brittle, and the mechanical limit for coated conductors depends on the direction of the force. When the limit is exceeded, the current carrying ability of the cable is compromised. We quantified the critical transverse pressure at which the performance of the cable is decreased. Various round strands were fabricated, exploring different reinforcement options. The critical transverse pressure is measured on a strand by testing it at liquid nitrogen temperature, applying the force thanks to an anvil. The measured critical transverse pressure values indicate which strand designs should be discarded, i.e. when the measured critical transverse pressure values are lower than the nominal ones foreseen in the full cable design. For one of the reinforcement options, a finite element mechanical model was developed to better understand the mechanics and to propose improvement to the cable design. It was found that the performance might be improved by wrapping the strand with a wire whose thermal expansion coefficient is higher than the of copper. The strand is precompressed during the cool down, decreasing the stress that causes the rupture of the tapes.

EPFL2022

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Three design concepts, namely, WP#1, WP#2, and WP#3, for the low-T-c superconductor DEMO toroidal field coil was proposed in 2014. This paper is focused on the thermal-hydraulic analysis of all the designs using simplified models, which includes: 1) hydraulic analysis-calculation of the mass flow rates in each conductor at operating conditions during the dwell time; 2) heat removal analysis-calculation of the steady-state mass flow rates and temperature profiles in each conductor as functions of the nuclear heat deposition rate; and 3) estimation of the maximum quench temperature and pressure in each conductor assuming the extreme scenario for the maximum pressure. The detailed analysis of the WP#1 design in burn and in quench conditions using the THEA code was also carried out. It took into account the expected electromagnetic and heat load maps along each conductor and different quench initiation scenarios leading to the maximum hot spot temperature or to the maximum pressure. Our analysis shows that the temperature margin in the WP#1 andWP#3 conductors is sufficiently large, but it is too small in some WP#2 conductors. The hot spot temperatures in some WP#1 cables calculated with THEA are too high. These results provide information for further improvements of the conductors' design.

Institute of Electrical and Electronics Engineers2016

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High current conductors for superconducting fusion magnets

2000

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EPFL2022