Considerations against a force compensated coil

The cost of structural components in a large superconducting coil such as SMES may well exceed the coil and cryostat cost. As a result, the idea of constructing a system composed of two different coil types assembled in such a way that the forces balance and reduce the total structural requirement is often proposed. A suitable geometry has never been found for the fundamental reason that there can be no force-compensated solution. The general problem is presented, and an analysis of the energy stored and stresses produced in the structure is described in a fundamental way. Finally, relation between structural mass M and stored energy E that is valid for all magnetic systems is developed