This series of academic training lectures will introduce the key topics related to the future of superconducting magnet technology based upon “high temperature superconductors” which have the potential to generate much higher magnetic fields than NbTi and Nb3Sn.
The series is comprised of five lectures. The first two will introduce some of the basic physics of the phenomenon of superconductivity, including the discovery of superconductivity, the difference between type I and type II superconductors, the thermodynamics of the superconducting state, magnetic vortices, magnetic flux pinning, the Bean critical state model and magnetization. The physics discussion will not focus on detailed quantitative rigor, but instead on conceptualization of the behavior.
The third lecture will introduce the technical superconducting materials that are used in conductors and magnets. After a brief overview of NbTi and Nb3Sn, the focus of this lecture will be on the emerging high temperature superconductors which have potential for future high energy physics magnets: (RE)BCO coated conductors and Bi2212 round wires. Each of these materials will be introduced, including their crystal structures (and how their intrinsic anisotropy influences their behaviors), how they are formed, and the challenges that must be overcome for them to become useful in high field magnets. Although these two materials have some similarities, from the perspective of technical challenges they are quite different; these differences will be presented and explored. Future directions that are likely to lead to significant improvements will also be presented.
The fourth lecture will focus primarily on the how technical superconductors respond to mechanical stress and stain, i.e., their electromechanical behavior. Again, after a brief overview of the behavior of of NbTi and Nb3Sn, the focus will be on (RE)BCO and Bi2212 conductors. For each material, their known behavior will be presented, including the performance limiting failure modes, the underlying causes of degradation and failure, and future directions that may lead to significant improvements.
The final lecture will discuss quench protection issues for HTS magnets. In this lecture, the focus will be on the unique challenges of HTS magnets, including the very slow quench propagation velocity and the uncertain failure limits. Potential solutions and current research directions will be discussed.
Kobe Steel Distinguished Professor
Head, Department of Materials Science and Engineering
North Carolina State University - USA