Analysis of ripple and error field due to using the ferritic steel insert in EAST

Chinese Experimental Advanced Superconducting Tokamak (EAST) is ITER-like Superconducting (SC) Tokamak with divertor configuration. However, EAST device has 16 toroidal field coils (TFCs) whose ripple amplitude is 0.67% higher than 0.3% of acceptable level of ITER at separatrix point. In order to improve the plasma control and confinement and have more contribution to ITER Physics, it is expected to reduce the TF ripple to ITER acceptable level. In this contribution, it was preliminarily investigated for installation of the appropriate ferristic steel insert inside EAST vacuum vessel to reducing the ripple based on electromagnetic analyses. Results indicated the ripple amplitude could be achieved to the expected level of less than 0.3%. Simultaneously, the error fields introduced due to installation of the ferristic steel insert was analyzed and not beyond scope of physics requirement.