Session CO3 - NSTX and Other ST.
ORAL session, Monday afternoon, November 15
Room 204/205, SCC
Spherical torus and tokamak experiments show that the combination of sufficient plasma rotation and a resistive wall can stabilize ideal kink/ballooning modes. However, toroidal rotation damping has been observed at sufficiently high plasma beta, eliminating passive stabilization. Rapid and global damping at high beta above the ideal MHD no-wall limit experimentally expedites mode locking and plasma beta collapse. ELMs lead to edge rotation damping that is typically insignificant. Resonant electromagnetic drag may explain rotation damping for resistive modes with small island width, while non-resonant neo-classical toroidal viscous drag is in quantitative agreement with measured global damping in resistive wall mode, 1/1 mode, and local damping in ELMing plasmas. A pair of non-axisymmetric coils was used to generate an n=1 magnetic field perturbation which allowed greater rotation control. Quantitative comparison is made between theory and experiment to determine the physics and parameter dependence of the damping evolution for the observed instabilities.