Simulation of magnetic shielding for DIXE

As a pathfinder for HUBS, Diffuse X-ray Explorer (DIXE) is a proposed X-ray spectroscopic survey experiment for the China Space Station. The detector assembly contains the transition edge sensor (TES) microcalorimeter and readout electronics based on the superconducting quantum interference device (SQUID) on the cold stage. TES and SQUID are both sensitive to the magnetic field, so a hybrid shielding structure consisting of an outer Cryoperm shield and an inner niobium shield is used to attenuate the magnetic field. From a zero-field cooling (ZFC) simulation using COMSOL Multiphysics, the shielding factor reaches 105-106, taking into account the necessary openings. Dynamically, the field cooling (FC) process is simulated where a magnetic field is found to be trapped inside the Niobium shielding. Helmholtz coils are utilized to counteract the initial magnetic field. This paper will describe the design and simulations of magnetic shielding for DIXE.