Parametric Study on Effect of Friction and Overbanding in Screening Current Stress of LBC Magnet

Magnetic stress is of particular concern for ultra high field magnets, especially, peak hoop stress of those magnets may be locally concentrated by the screening current stress (SCS). For instance, the Little Big Coil (LBC), which was designed, constructed, and operated by a collborate team led by NHMFL, generated the world record magnetic field of 45.5 T, but the conductor in LBC experienced plastic deformation due to excessive SCS. In this paper, to further analyze details of the mechanical stress behavior of LBC magnet, the effect of friction coefficient and overband radial build on stress alleviation is investigated by the parametric study. First, total current density with screening current is calculated by using the H-formulation together with domain homogenization method. Later, the entire magnet structure is modeled by the 2D finite element method to represent preload and axial i…