Abstract
DIII-D discharges with values of beta (the ratio of plasma pressure to magnetic pressure) up to 12.5% demonstrate that a resistive wall can stabilize low- magnetohydrodynamic (MHD) modes. In discharges with broad current profiles, beta exceeds the ideal MHD stability limit by at least a factor of 1.3 assuming no wall, but remains below the limit calculated under the assumptions that the vacuum vessel is a perfectly conducting wall. Plasma rotation is essential to stabilization, and instabilities resembling the predicted “resistive wall mode” appear only when the rotation velocity approaches zero.
- Received 26 October 1994
DOI:https://doi.org/10.1103/PhysRevLett.74.2483
©1995 American Physical Society