Ideal magnetohydrodynamic instabilities with low toroidal mode numbers localized near an internal transport barrier in high-βp mode plasmas in the Japan Atomic Energy Research Institute Tokamak-60 Upgrade

Local steep pressure gradient generated near an internal transport barrier drives a radially localized magnetohydrodynamic (MHD) instability with low toroidal mode number (n) in the high-βp mode plasma in the Japan Atomic Energy Research Institute Tokamak-60 Upgrade (JT-60U) [Y. Koide et al., Phys. Plasmas 4, 1623 (1997)]. The instability occurs in the βp regime lower than that for the βp-collapse and its growth rate is of the order of the ideal MHD instability. By a linear analysis of ideal MHD stability, low n modes localized near the internal transport barrier are found to be destabilized in the situation that the bootstrap current driven by the steep pressure gradient reduces the local magnetic shear (s approx-lt 0) where the safety factor is right close to an integer value. copyright 1997 American Institute of Physics