A study of segmented superconductive energy storage solenoids

The concept and development of magnetic energy storage has been studied recently. It has been found that large single-layer superconductive energy storage solenoids are economically attractive if they are buried in tunnels in bedrock. The radial forces can be transferred directly through low-thermal-conductivity, high-compression stress struts. To reduce the cold structure required to support axial forces, the concept of segmented solenoids was proposed at the University of Wisconsin. In this paper a study of various cost parameters regarding the solenoid aspect ratio and the separation distances between tunnels is presented. The amount of axial structure required is calculated by the virtual work method. To reduce the mechanical strain in the conductor, it has been suggested that the conductor be rippled: an analytical expression for the increase in the magnetic field due to rippling is derived. (author)