Abstract
The superconducting magnet operates in conditions of complex electromagnetics, which could cause hysteresis loss and coupling losses, the so-called AC losses. In this chapter, the AC losses calculation of superconductor will be discussed in detail. Usually, the superconducting magnets are wound by superconducting coils, which are twisted by superconducting wires. The length of superconducting wires is hundreds of meters, while the length of coils is millions of meters; thus, joints are needed to join the coils. The design of different patterns of joints, such as twin-box joint, butt joint, and petal overlap joint, will be introduced in detail. Joule heat and AC losses in the joint may cause locality quench, and if the design stability margin of the magnet could not cover the joule heat and losses, the locality quench will cause global quench of the magnet. The temperature rise caused by joule heat and AC losses will be discussed in detail. Furthermore, the magnetic Lorentz force and mechanical displacement could cause locality quench, which may cause a global quench, once the coolant could not take away the heating pulse. The simulation of the stability and quench behavior of the superconducting cable-in-conduit conductor will be introduced in detail.