Evolution of Toroidal Alfvén Eigenmode Instability in TFTR
Author: K.L. Wong, R. Majeski, M. Petrov, J.H. Rogers, G. Schilling, J.R. Wilson, H.L. Berk, B.N. Breizman, M. Pekker, and H.V. Wong
The nonlinear behavior of the Toroidal Alfvén Eigenmode (TAE) driven unstable by energetic ions in TFTR [Phys. Plasmas 1, 1560 (1994)] is studied. The evolution of instabilities can take on several scenarios: a signle mode of several modes can be driven unstable at the same time, the spectrum can be steady or pulsating and there can be negligible or anomalous loss associated with the instability. This paper presents a comparison between experimental results and recently developed nonlinear theory. Examples include the structure of the saturated pulse that emerges from the onset of instability of a single mode and the decrease but persistence of TAE signals when the applied rf power is reduced or shut off.