CHAPTER 2: Magnets

This chapter explains some of the basic principles that are used in the construction of a homogeneous superconducting magnet for magnetic resonance, including the basic physics of magnetic field generation, as well as superconducting materials and their properties. Concentrating on magnet design for human MRI, the chapter describes how the stray-field of a magnet can be controlled and how the magnetic field is stabilised. The cryogenic design and practical considerations for the operation of a magnet system are included with a number of key safety recommendations. Finally, the article discusses future developments, in particular operation of human systems at field strengths in excess of 10 T, and cryogen-free systems.