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.

Intense fast-ion populations created by neutral-beam injection into a tokamak can destabilize toroidicity-induced Alfvén eigenmodes (TAE modes) or internal kink modes. Experimentally, these modes stabilize when fast ions are ejected from the plasma, producing a cycle of relaxation oscillations about the marginal stability point. A pair of coupled differential equations describes this cycle. This simple theoretical formalism successfully describes the cycles observed during TAE experiments in DIII-D [Plasma Physics Controlled Nuclear Fusion Research, 1986 (International Atomic Energy Agency, Vienna, 1987), Vol. 1, p. 159]. © 1993 American Institute of Physics.