Toroidal Alfvén eigenmodes (TAEs) of low toroidal mode number, n=1 and 2, are observed in neutral-beam-heated plasmas in the compact helical system heliotron/torsatron. The observed frequency is proportional to the computed TAE frequency and lies near the lower bound of the innermost TAE gap. The modes are excited only when the beam velocity exceeds about half the central Alfvén velocity and when the net plasma current induced by coinjected neutral beams is in the required range. The modes are localized in the plasma core region, between 0.2 and 0.6 of the plasma minor radius.
All Science Journal Classification (ASJC) codes
- Physics and Astronomy(all)