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Internal kink mode dynamics in high-β NSTX plasmas

2005; IOP Publishing; Volume: 45; Issue: 7 Linguagem: Inglês

10.1088/0029-5515/45/7/001

1741-4326

J. Ménard, R. E. Bell, E. D. Fredrickson, D. Gates, S. Kaye, B. LeBlanc, R. Maingi, S. S. Medley, W. Park, S.A. Sabbagh, A.C. Sontag, D. Stutman, K. Tritz, W. Zhu, the NSTX Research Team,

Solar and Space Plasma Dynamics

Saturated internal kink modes have been observed in many of the highest toroidal β discharges of the National Spherical Torus Experiment (NSTX). These modes often cause rotation flattening in the plasma core, can degrade fast-ion confinement and in some cases contribute to the complete loss of plasma angular momentum and stored energy. Characteristics of the modes are measured using soft x-ray, kinetic profile and magnetic diagnostics. Toroidal flows approaching Alfvenic speeds, island pressure peaking and enhanced viscous and diamagnetic effects associated with high-β may contribute to mode nonlinear stabilization. These saturation mechanisms are investigated for NSTX parameters and compared with experimental data.