A magnetic solar sail is a large
superconducting coil, tens of kilometers across, that carries a large electric current that forms a huge magnetic field. It was investigated by
Robert Zubrin with a grant from NASA Institute for Advanced Concepts (
NIAC).
Unlike a conventional solar sail, the magnetic solar sail would not interact with the sunlight itself as light is unaffected by magnetic fields.
Instead, this huge magnetic field reflects the many charged particles in the solar wind and gives a tiny kick to the vehicle; providing thrust. By angling the coil relative to the sun, thrust at an angle to the Sun (rather than straight out) can be produced.
The main idea of the magnetic solar sail is to try to have the maximum possible area, using a magnetic field that weighs essentially nothing. Projections show that the huge size of the coil gives better performance than conventional solar sails.