Measurements of beam-ion confinement during tangential beam-driven instabilities in a bean tokamak experiment

During tangential injection of neutral beams into low-density tokamak plasmas with β>1%, instabilities are observed that degrade the confinement of beam ions. Neutron, charge-exchange, and diamagnetic loop measurements are examined in order to identify the mechanism or mechanisms responsible for the beam-ion transport. The data suggest a resonant interaction between the instabilities and the parallel energetic beam ions. Evidence for some nonresonant transport also exists.