Design of a force-free inductive storage coil

Abstract

Force-free coils have been considered for various applications as energy storage devices. A novel energy storage system consisting of both toroidal and poloidal coils has been developed. In this system, the Lorentz forces on the two coils are in opposition and can be made to cancel by having the proper ratio of ampere-turns in the two coils. A general discussion of force-free coil design is given,and the toroidal-poloidal coil system is described. The materials costs of magnets constructed with this and other geometries are compared. The conclusions are that conductor cost of this system lies between those of solenoids and toroids, and that the costs of structural material may be considerably less than either of these simpler coils.

Preliminary investigation of force-reduced superconducting magnet configurations for advanced technology applications

“…One of these configurations, shown in Figure 10, has been proposed by Mawardi (1975). In this configuration the poloidal and toroidal components have been decomposed by setting a coil carrying a poloidal current inside a toroidal shell which supports coils carrying a toroidal current.…”

“…Coi! carrying poloidalcurrent Thome, 1982) " Mawardi (1975) analysis revealed that no significant gains are made at low energy storage, but beyond I M J, substantial gains (40%) could be achieved with force-free coils.…”

“…Reduced force energy storage concept. The poloidal coils produce outward forces which are in opposition to the inward forces of the toroidal coils (Mawardi, 1975)…”