Abstract: A device for separating particles according to their respective masses includes a substantially cylindrical wall of inner radius, “Rwall”, that surrounds a chamber and defines a longitudinal axis. A multi-species plasma having relatively cold ions is initiated at a first end of the chamber within a relatively small radius, “rsource”, from the longitudinal axis. A hollow cylinder having an outer radius, “Router”, is positioned at the second end of the chamber and centered on the axis. Cross electric and magnetic fields (E×B) are established in the chamber that are configured to send ions of relatively high mass on trajectories having a radial apogee, rapogee, that is greater than the cylinder's outer radius (r>Router). After reaching apogee, these ions lose energy and strike the cylinder where they are collected. Low mass ions are placed on small radius helical trajectories and pass through the hollow cylinder.

Abstract: A band gap mass filter for separating particles of mass (M1) from particles of mass (M2) in a multi-species plasma includes a chamber defining an axis. Coils around the chamber generate an axially aligned magnetic field defined (B=B0+B1 sin ?t), with an antenna generating the sinusoidal component (B1 sin ?t) to induce an azimuthal electric field (E?) in the chamber. The resultant crossed electric and magnetic fields place particles M2 on unconfined orbits for collection inside the chamber, and pass the particles M1 through said chamber for separation from the particles M2. Unconfined orbits for particles M2 are determined according to an ?-? plot ( ? = ? 0 2 + ? 1 2 / 2 4 ? ? 2 , and ? ? ? ? = ? 0 ? ? 1 8 ? ? 2 ) , where ?0 is the cyclotron frequency for particles with mass/charge ratio M, and wherein ?0=B0/M and ?1=B1/M.