The propagation of an intense neutralized ion beam (v∼5 × 10 8 cm/sec, n∼1010 cm-3) through a large insulated vacuum chamber is measured as a function of magnetic field strength and direction. When the beam propagates parallel to the applied field, beam divergence is reduced. When the beam propagates perpendicular to the applied field, the downstream beam density decreases with increasing field strength. When the beam velocity vector intersects the magnetic field at an oblique angle, beam propagation is determined primarily by the perpendicular component of the field. © 1992 American Institute of Physics.