X-IFU magnetic field modelling including multi-stage ADR and FPA using a hybrid 2D axisymmetric- and 3D-approach

This work describes the magnetic modelling process of the X ray Integral Field Unit (X-IFU) multi-stage ADR last stage cooler and its effect on the Focal Plane Assembly (FPA) for the Athena X-ray observatory. Superposition of 2D axis-symmetric non-linear magnetic models are used to predict magnetic field levels outside the ADR cooler in absence of the FPA. Spatial variations of the relative permeability inside the ADR stage iron shields at different coil current levels is used to create a 3D linearized magnetic model. The FPA and its magnetic shields are added to this 3D model to make final predictions for the magnetic field inside the FPA produced by the multi-stage ADR at various points during the operation cycle.