Chinese Acad Sci, Inst High Energy Phys, Beijing 100049, Peoples R China
In this paper the influence of the space magnetic field on the performance of a superconducting niobium bulk cavity is introduced briefly. And an effective magnetic shielding method for superconducting cavity vertical test is presented. The initial permeabilities of eight different kinds of Fe-Si and Fe-Ni materials at liquid helium or liquid nitrogen temperature has been measured to compare with those at room temperature. The measurement data are given also. Based on it a double layers cylinder magnetic shield has been developed for the cryostat of 1.3GHz superconducting cavity.