Design considerations for Force-Balanced Coil applied to SMES

Strong electromagnetic farce caused by high magnetic field and large coil c urrent is a serious problem in Superconducting Magnetic Energy Storage (SME S) systems. rn facing this problem, we proposed the concept of Force-Balanc ed Coil (FBC) which is a helical-winding toroidal coil and can reduce the c entering force of Toroidal Field Coil (TFC). The helical-winding of the FBC is modulated in order to reduce the torsional force. This paper describes the cost-related parameters of the FBC in terms of the dimension of the coi l, the ampere-meters of superconductors and the surface area of the coil co mpared with the TFC and the solenoid. Moreover, we discuss the structure re quirements by the virial theorem and improve the concept of PBC in terms of the further optimization of SMES through the structural analysis.