Observation of Energetic Particle Driven Modes Relevant to Advanced Tokamak Regimes [report]

R. Nazikian, B. Alper, H.L. Berk, D. Borba, C. Boswell, R.V. Budny, K.H. Burrell, C.Z. Cheng, E.J. Doyle, E. Edlund, R.J. Fonck, A. Fukuyama (+25 others)
2004 unpublished
Measurements of high frequency oscillations in JET, JT-60U, Alcator C-Mod, DIII-D and TFTR plasmas are contributing to a new understanding of fast ion driven instabilities relevant to Advanced Tokamak (AT) regimes. A model based on the transition from a cylindrical-like frequency-chirping mode to the Toroidal Alfvén Eigenmode (TAE) has successfully encompassed many of the characteristics seen in experiments. In a surprising development, the use of internal density fluctuation diagnostics has
more » ... diagnostics has revealed many more modes than has been detected on edge magnetic probes. A corollary discovery is the observation of modes excited by fast particles traveling well below the Alfvén velocity. These observations open up new opportunities for investigating a "sea of Alfvén Eigenmodes" in present scale experiments, and highlight the need for core fluctuation and fast ion measurements in a future burning plasma experiment.
doi:10.2172/836089 fatcat:2zigaswtsfa6blhxdamqvmglli