Structural Finite Element Evaluation of Twisted Stacked-Tape Cables for High-Field Magnets

Structural characteristics of twisted stacked-tape cables (TSTC) for high-field magnet applications were investigated using finite-element analysis. Conductor support structures for high-field magnets are very important because magnet conductors require bendability during coil winding but at the same time must be supported against the large electromagnetic Lorentz loads experienced during magnet operation. In this paper, we discuss a numerical analysis of an untwisted 40-tape TSTC subjected to transverse loads as high as 300 kN/m (20 kA, 15 T). Two conductor support methods were investigated: a solid cylindrical copper core and a solder filled copper tube. The influence of the stack orientation angle with respect to the applied transverse load was studied to take into consideration the twisting of the tape stack in a real TSTC magnet conductor. The solid core support method was found to provide better structural support compared to the solder filled tube method and a lower stress in the tape stack particularly at a stack orientation of 45 ° was observed. A design optimization study was also performed for the solder filled tube configuration. A stronger tube material, larger tube diameter, and greater tube thickness were all found to reduce the stress in the tape stack.