Stabilization Of Ballooning Modes With Sheared Toroidal Rotation

Download or read book Stabilization of Ballooning Modes with Sheared Toroidal Rotation written by and published by . This book was released on 2001 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: A new code demonstrates the stabilization of MHD ballooning modes by sheared toroidal rotation. A shifted-circle model is used to elucidate the physics and numerically reconstructed equilibria are used to analyze DIII-D discharges. In the ballooning representation, the modes shift periodically along the field line to the next point of unfavorable curvature. The shift frequency (d[Omega]/dq where[Omega] is the angular toroidal velocity and q is the safety factor) is proportional to the rotation shear and inversely proportional to the magnetic shear. Stability improves with increasing shift frequency and, in the shifted circle model, direct stable access to the second stability regime occurs when this frequency is a fraction of the Alfven frequency[omega][sub A]= V[sub A]/qR. Shear stabilization is also demonstrated for an equilibrium reconstruction of a DIII-D VH-mode.