Diameter Change of Dry Wound REBCO Solenoid Pancake Coil by Winding Tension

Winding stress plays a key role in maintaining the initial position of the winding pack in manufacturing superconducting magnets. In this paper, we study the effect of winding tension on radial dimension change of dry wound solenoid pancake coils(PCs). By comparing experiment and simulation of winding results for 150 turn stainless steel and REBCO dry wound pancake coil, effective radial Young's modulus of winding pack is estimated to be 0.5–1.6 GPa and 0.28–0.39 GPa for stainless steel(SS) and REBCO PC depending on the winding tension. Lower effective Young's modulus than the material stiffness(195 GPa for SS and 169 GPa for REBCO) and the increasing trend of Young's modulus with higher tension may be explained by the compressible characteristics of rough surfaces in contact. After that, we found irreversible radial dimension change of REBCO dry wound PCs, while not for SS one. This phenomenon may be originated from the flattening of the REBCO conductor by winding pressure against the intrinsic height difference of REBCO conductor.