3D Field Quality in the SIS100 Dipole Magnet during Fast Ramping

In order to calculate the field quality in the aperture of the SIS100 dipole magnet, a finite element discretization based on a tetrahedral mesh is applied. An anisotropic nonlinear material model resulting from a homogenization of the laminated iron yoke is necessary to model the effects of ferromagnetic saturation [1]. The excitation current in the superconducting coils amounts to 48 kA and varies with time according to cycle 2c corresponding to a ramp rate of 4 T/s for the magnetic flux density [2]. In the numerical model used for the simulations (Fig.1(a)), yoke modifications such as air slots and negative pole shimming (Fig.1(b)) are considered while the yoke length is shortened from 3.002 m to 0.5 m. Furthermore, the conductive