High Beta and Enhanced Confinement in a Second Stable Core VH-Mode Advanced Tokamak

Abstract

A new, enhanced performance tokamak regime, the second stable core VH-mode (SSC-VH), with a self-consistent VH-mode transport barrier and a large second stable core pressure gradient supported by negative central magnetic shear, is proposed. The SSC-VH is shown to have promising $\ensuremath{\beta}$ limits simultaneously with enhanced confinement and a large, well-aligned bootstrap current fraction. Simulations show that a wall-stabilized high $\ensuremath{\beta}$, high-confinement SSC-VH can be maintained self-consistently in a steady state, by noninductive current drive.