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Research project title

Development of 3-D finite element models of superconducting cables for high field magnets

Education level

Doctorate

Director/co-director

Director: Frédéric Sirois

Co-director(s): Xiaorong Wang, Lawrence Berkeley National Laboratory, California, U.S.A.

End of display

March 31, 2023

Areas of expertise

Unit(s) and department(s)

Department of Electrical Engineering

Laboratory of Superconductivity and Magnetism (LSM)

Lawrence Berkeley National Laboratory, California, U.S.A.

Conditions

Background:  Undergraduate and masters in a field comprising a strong component of physics and/or mathematics.

Skills and interests: Numerical methods, electromagnetism and physics in general.

Personal qualities: Autonomy, critical thinking and creativity. Recommendations from referees (to be sent with the application form) should provide specific comments on each of these aspects.

Working language: We seek a candidate with fluent English, both written and spoken, since the project is realized with a U.S. laboratory. A working knowledge of French, although not mandatory in this project, would help the candidate, since Polytechnique Montréal is a French-speaking institution. In the framework of this project, the thesis will have to be written in English.

Admission procedure and forms

Detailed description

This project is a joint project between Polytechnique Montreal and the LBNL (Lawrence Berkeley National Laboratory), located in California, U.S.A. The main objective is to develop a complete simulation model of the "quench" (i.e. thermal runaway) in superconducting cables intended for electromagnets with strong magnetic fields. Strong field electromagnets are used in particle accelerators, magnetic resonance imaging systems and possibly in nuclear fusion reactors.

Polytechnique Montréal has a cutting-edge expertise in finite element modeling of electromagnetic and thermal modeling of superconducting wires and cables, having developed the most efficient models to date (the most recent results are currently being published). In addition, Polytechnique Montreal has played a pioneering role in the development of approaches to protect superconducting wires against quench, notably by introducing the concept of "Current Flow Diverter" (CFD), patented in U.SA. As part of this project, this expertise will be used to accelerate the development of superconducting cables for high-field electromagnets, coordinated by the American consortium Magnet Development Program (MDP, see https: // usmdp. lbl.gov/why-usmdp/), lead by the LBNL.

More specifically, the new models to be developed will have to push the limits of the existing models even further in order to take into account the following aspects:

i) The inhomogeneity of the critical current along the superconducting tapes that make up the cables;

ii) The contact resistances between the various superconducting tapes, as well as between the metallic parts of the cables (these resistances also exhibit spatial inhomogeneities);

iii) Mechanical pressure (internal stress) exerted between the different surfaces in play.

The approach envisioned is pursue with the strength of the current Polytechnique’s models, which assimilate the conductive and insulating thin layers in play by interfacial physics models in the finite element problem, thus making it possible to solve problems of a very high complexity (millions of degrees of freedom) with a greatly reduced computational effort. For example, with this approach, it is possible to simulate an electromagnet of several thousand turns in just a few hours, whereas this problem was still impossible to simulate five years ago.

The doctoral student will work in close collaboration with LBNL researchers in order to validate his results and calibrate his models with experimental results. The experiments will be carried out by experienced researchers, in a specialized infrastructure devised for this purpose.

Financing possibility

A financial support is available for the successful candidate (only top level candidates will be considered for this position). The amount of financial assistance will be at the level proposed by Polytechnique Montréal, i.e. at least 22000 $ per year (Canadian dollars), for at most 4 years, in order to allow the candidate to work full time on his thesis. Additional funds will cover the stays in California.

A student who obtains his own scholarship (NSERC, FRQNT or other) will be granted a bonus (typically 25% of the amount of the scholarship, to discuss case by case).

Frédéric Sirois

Frédéric Sirois

Full Professor

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