Direct Measurement of the Damping of Toroidicity-Induced Alfvén Eigenmodes

This Letter presents the first direct experimental measurements of the damping of toroidicity-induced Alfvén eigenmodes (TAE), carried out in the JET tokamak. These measurements were obtained during the first experiments to drive these modes with antennas external to a tokamak plasma. Different regimes corresponding to different dominant TAE absorption mechanisms with a wide range of damping rates, ${10}^{-3\mathrm{}}\le \gamma /\omega \le {10}^{-1\mathrm{}}$, have been identified in Ohmically heated plasma discharges.