99549 - APPLIED SUPERCONDUCTIVITY FOR ENERGY TRANSITION M

Learning outcomes

This course aims to illustrate the fundamental concepts related to the analysis and synthesis of magnetic systems and large-scale applications of superconductivity for the energy transition. The electrical and magnetic properties that characterize the behavior of low and high critical temperature superconducting materials are introduced. The most relevant technological issues concerning electromagnetic, thermal (cryogenics) and mechanical aspects of superconducting devices are treated in the course. The working principles and design criteria of the main large-scale applications of superconductivity are described, with particular reference to magnet technology (controlled thermonuclear fusion machines, accelerators, magnetic resonance imaging systems, mag-netic levitation) and to the power systems (cables, electrical machines).

Course contents

Magnet Technology and Engineering

Type I and type II superconducting materials.History and theories of superconductivity . Critical surface. High and low critical temperature materials. Last generation superconducting materials. Alternating current losses.

Magnetic field generating systems: permanent magnets, resistive electromagnets, superconducting eletromagnets.

Geometric configurations: Solenoid, toroidal, saddle, racetrack, cos (q), Bitter type electromagnets. Permanent magnets and Halbach arrays.

Winding methods: helix, pancake, double pancakes.

Type of conductors: LTS and HTS wires and tapes. Rutherford cables, Cable in Conduit Conductors (CICC), Roeble conductors, CORC.

Electromagnetics: magnetization of superconducting filaments, wires and cables.

Cryogens and cooling techniques. Helium phase diagram. Cooling methods. Conduction cooled (cryogen free) superconducting magnets.

Thermal Stability: Transition from superconducting to normal state (quench). Minimum Quench Energy (MQE) and Minumum Propagating Zone. Quench detection and protection systems.

Applications

Magnetic Resonance Imaging: Working Principle. Uniformity and intensity of the field, signal to noise ratio. Gradient coils. Stray field shielding.

Superconducting Magnets for Controlled Termonuclear Fusion: tokamak and stellarator configurations. Magnetic system for a tokamak: toroidal field magnets, central solenoid, corrector magnets. ITER project.

Magnets for Particle Accelerators: the CERN LHC Project. Field harmonics and the problems of field quality. Field errors due to geometry, non linearity of iron (saturation) and non-linearity of superconductors (magnetization). Dipoles, quadruples and correcting magnets. Magnets for the Particle Detectors.

High field magnets (above 30 T): Bitter magnets, non-distructive pulses, distructive pulses.

Power Applications

Superconductive AC and DC power cables.

Superconductive current limiters for power systems: resistive, inductive and hybrid limiters.

Superconducting Magnetic Energy Storage Systems (SMES): Operating principle, design criteria. Charge and discharge dynamics, ripple and protection systems. Superconducting permanent magnets for rotating electric machines: superconductive bulks, in situ or ex situ location magnetization. Torque density.

Magnetic separation: principle of operation. Open Gradient or High Gradient Configuration. Applications in the mining and steel industries.

Superconductive systems for induction heating in industrial environments.

Critical high-temperature superconducting cable design methods. Vacuum techniques and cryogenic systems.

Magnetic Levitation: Active and passive levitation. Trains MAGLEV. Magnetic bearings. Levitation stability.

 

Readings/Bibliography

1. M. Wilson, “Superconducting Magnets”, Clarendon Press Oxford, New York, 1982
2. Kratz and Wyder, “Principles of pulsed magnet design”, Springer, 2002
3. G. Krabbes, G. Fuchs, W.-R. Canders, H. May, R. Palka, “High Temperature Superconductor Bulk Materials”, Wiley-VCH, 2006
4. Y. Iwasa, “Case Studies in Superconducting magnets”, Plenum Press, 1994
5. Thome and Tarrh, “MHD and Fusion Magnets”, J.Wyley, 1992.
6. P. Tixador, “Les supraconducteurs”, Hermes, Paris, 1995.

Teaching methods

The course contents are illustrated during the lectures. Three computer practices will be carried out during the course, aimed at a better understanding of the design methodology of solenoids, of the field harmonics in accelerator magnets and of the quench initiation and propagation in superconducting magnets.

Assessment methods

The exam will consist of an oral examination at the end of the course. No partial exams are foreseen during the course. During the oral examination the topic discussed during the course will be treated by the student. The examination will be aimed at assessing that the student is able to adopt a correct technical language and has reached an organic knowledge of the topics developed during the course. The ability of the student to apply the acquired knowledge to the solution of new problems will be verified. The final mark will depend on the degree of fulfilling of the aforementioned requisites.

Teaching tools

The lecture notes of the course are available on the website Virtuale of the University of Bologna (https://virtuale.unibo.it). Presentations given during the course are also available on this website.

Office hours

See the website of Marco Breschi

See the website of Antonio Morandi