High-[Formula presented] Equilibria of Drift-Optimized Compact Stellarators

Compact stellarator configurations have been obtained with good neoclassical confinement that are stable to both pressure- and current-driven modes for high values of [Formula presented]. These configurations are drift-optimized tokamak-stellarator hybrids with a high-shear tokamak-like rotational transform profile and [Formula presented] that is approximately poloidally symmetric. The bootstrap current is consistent with the required equilibrium current and, while larger than that in existing stellarators, is typically only a small fraction ([Formula presented]) of that in an equivalent tokamak. These configurations have strong magnetic wells and consequently high interchange stability [Formula presented] limits up to [Formula presented]. Because of the reduced bootstrap current, these configurations are stable to low-[Formula presented] ideal MHD kink modes with no wall stabilization for values of [Formula presented] ([Formula presented]) significantly larger than in an equivalent advanced tokamak.