A configuration of magnetic fields using properties of cylindrically symmetric permanent
magnets is presented as a candidate to produce a high purity charged particle source or
trap. Cylindrically symmetric hollow permanent magnets produce magnetic field point cusps
on the axis of symmetry. A magnetic field point cusp reflects all particles that lie outside a
narrow region of phase space, a region dependent on particle kinetic energies and on the
magnetic field intensity. An analysis of the phase space of positron trajectories entering and …