AVIS DE SOUTENANCE
Monsieur Romain Babouche
« Sciences pour l’ingénieur » : spécialité « Energétique »
Soutiendra publiquement ses travaux de thèse intitulés :
« Coupling losses and induced instabilities in superconducting cables for fusion : multiphysics modelling and experimental validation »
dirigés par Dr. Frédéric TOPIN
Soutenance prévue le jeudi 14 décembre 2023 à 13h00
Lieu : IRFM – René Gravier – Centre de Cadarache 13115 Saint Paul Lez Durance
Et par SKYPE (voir lien ci-dessous)
Composition du jury proposé :
|
Dr. Marco BRESCHI |
University of Bologna (IT) |
Rapporteur |
|
Dr. Kamil SEDLAK |
EPFL, Swiss Plasma Centre (CH) |
Rapporteur |
|
Dr. Yannick MARANDET |
Aix-Marseille Université |
Examinateur externe |
|
Dr. Hélène FELICE |
CEA Saclay / IRFU |
Examinatrice externe |
|
Dr. Alfredo PORTONE |
Fusion for Energy (ESP) |
Examinateur externe |
|
Dr. Carmine SENATORE |
Université de Genève (CH) |
Examinateur externe |
|
Dr. Arend NIJHUIS |
University of Twente (NL) |
Invité |
|
Dr. Ion TISEANU |
INFLPR (RO) |
Invité |
|
Dr. Frédéric TOPIN |
Aix-Marseille Université |
Directeur de thèse |
|
Dr. Louis ZANI |
CEA Cadarache / IRFM |
Encadrant CEA |
Keywords :
Nuclear fusion, cable in conduit conductors, AC loss, coupling loss, X-ray tomography, modelling, measurements.
Abstract :
This thesis is part of the ongoing research on fusion by magnetic confinement in reactors called tokamak. The generation of strong magnetic fields relies on superconducting magnets wound with Cable-in-Conduit Conductors which gather several hundreds or even thousands of strands twisted into stages.
Within the tokamak, numerous and large magnetic field variations are induced either to generate, maintain and control the plasma or during rapid discharges of the current contained in the coils. These variations induce current loops in the conductors passing from strand to strand through resistive zones and dissipating energy. These are the variable field losses also called coupling losses or AC losses. They are essential to take into account since the cooling design of these magnets must be adapted.
The objective of this thesis is to contribute to the modelling and the measurement of these losses on different conductors already used in a tokamak or at the prototype stage. These losses are modelled using the COLISEUM and MPAS models, both developed at CEA Cadarache. COLISEUM aims at predicting coupling losses solely from the geometric and electrical properties of the considered cable. In this thesis, the objective is to continue the development of the model to enable the use of real input parameters measured on conductors via X-ray tomography and the measurement of inter-strand electrical resistances. To this end, dedicated measurement campaigns were organized in collaboration with two European laboratories. An extensive analysis of the tomography is conducted to determine the genuine geometric parameters of various cables and also to characterize their properties in the broad sense. These data subsequently made it possible to deduce the equivalent electrical network to one of these cables from the study of the inter-strand distances and contacts. This network based on physical properties that are difficult to predict was combined with inter-strand resistance measurements on the same cable from which it was derived. This integrated approach to the development of the COLISEUM model made it possible to determine real input parameters whose use leads to very promising results.
Conversely to COLISEUM, the MPAS model relies on the prior measurement of losses to deduce the associated modelling. Here, this model is used on the measurements carried out during this thesis and is applied to practical cases encountered during tokamak operations.
The other experimental part of this thesis is based on the measurement of AC losses at the JOSEFA facility located at CEA Cadarache. As part of this work, five samples were measured over a wide frequency range. At very low frequencies, these measurements made it possible to highlight an unexpected behaviour of the losses which was until then invisible due to the lack of such measurements. Subsequently, comparisons and applications with the COLISEUM and MPAS models are carried out. Mainly based on the conductor of the toroidal field coils of the JT-60SA tokamak, the loss measurements made it possible to highlight the influence of the field direction on the generated losses when it is applied perpendicular to one or the other face of this rectangular-shaped conductor. Such characterizations are essential to ensure the stability of the magnet during operations. Eventually, the first AC loss measurements on a large sample (CEA EU-DEMO TF) have been conducted and show the capability of the JOSEFA test facility to host various sample types to provide both low and high frequency characterisations.
………………………………………………………………………………………………………………………..
Participer à une Réunion Skype
Vous n’arrivez pas à rejoindre cette réunion ? Essayer l’app web Skype
Participer par téléphone
+33 1 69 35 55 10 (France) Français (France)
ID de conférence : 864612233
Vous avez oublié votre code confidentiel de connexion ? |Aide
Condition d’accès :
• Depuis un Poste CEA équipé de Skype Entreprise (*): Cliquer sur le lien ci-dessus.
• Depuis un navigateur web (sauf Internet Explorer. Le poste n’a pas besoin d’être CEA ni d’être connecté au réseau CEA. Les smartphones et postes Linux sont supportés) : aller à https://vc.cea.fr et appeler 99+ID de conférence . Exemple: ID=1234567–> 991234567
• Depuis une salle de visioconférence CEA : 99+ID de conférence (depuis une salle de visioconférence hors CEA, appeler au préalable )
• Pour l’audio seul : Appeler le 0169355510
– Saisir l’ID et valider par la touche #
– Ne pas saisir la touche * et ne pas s’identifier
– Attendre qu’un participant vous autorise à entrer en conférence
* L’usage de l’audio nécessite un micro et un haut-parleur ou un casque/micro
Pour que l’on vous voit (optionnel),votre appareil doit être équipé d’une caméra.
(*) – Seul l’organisateur doit impérativement être raccordé à l’intranet CEA (en direct ou via VPN) pour que la réunion se déroule.
———————-
Access conditions :
• From a workstation CEA with Skype for Business client installed (*): Click on the link above.
• From a web browser (except Internet Explorer. The workstation does not need to be CEA or to be connected to CEA network. Linux, smartphones and workstations are supported) : go to https://vc.cea.fr and call 99+Conf ID.
• From a CEA videoference room : call 99+Conf ID (from Internet, call before)
• From audio only : Call +33 1 69 35 55 10, enter the Conf ID when asked.
– Confirm with the # key.
– Do not enter the * key.
– Simply wait, a participant will authorize you to join the conference.
* Audio experience will be better with an headset but you can use the built-in microphone and speaker of your phone.
In order for you to be seen (optional), your device must be equipped with a camera.
(*) – Only the organizer must be connected to the CEA intranet (directly or via VPN) for the meeting to proceed.
[!OC([040c])!]
………………………………………………………………………………………………………………………..