  The development of stellarators that use permanent magnet arrays to shape
their confining magnetic fields has been a topic of recent interest, but the
requirements for how such magnets must be shaped, manufactured, and assembled
remain to be determined. To address these open questions, we have performed a
study of geometric concepts for magnet arrays with the aid of the newly
developed MAGPIE code. A proposed experiment similar to the National Compact
Stellarator Experiment (NCSX) is used as a test case. Two classes of magnet
geometry are explored: curved bricks that conform to a regular grid in
cylindrical coordinates, and hexahedra that conform to the toroidal plasma
geometry. In addition, we test constraints on the magnet polarization. While
magnet configurations constrained to be polarized normally to a toroidal
surface around the plasma are unable to meet the required magnetic field
parameters when subject to physical limitations on the strength of present-day
magnets, configurations with unconstrained polarizations are shown to satisfy
the physics requirements for a targeted plasma.
