A New Path to Improve High beta(p) Plasma Performance on EAST for Steady-State Tokamak Fusion Reactor

High beta(p) scenario is foreseen to be a promising candidate operational mode for steady-state tokamak fusion reactors. Dedicated experiments on EAST and data analysis find that density gradient backward difference n is a control knob to improve energy confinement in high beta(p) plasmas at low toroidal rotation as projected for a fusion reactor. Different from previously known turbulent stabilization mechanisms such as E x B shear and Shafranov shift, high density gradient can enhance the Shafranov shift stabilizing effect significantly in high beta(p) regime, giving that a higher density gradient is readily accessible in future fusion reactors with lower collisionality. This new finding is of great importance for the next-step fusion development because it may open a new path towards even higher energy confinement in the high beta(p) scenario. It has been demonstrated in the recent EAST experiments, i.e., a fully non-inductive high beta(p) (similar to 2) H-mode plasma (H-98y2 >= 1.3) has been obtained for a duration over 100 current diffusion times, which sets another new world record of long-pulse high-performance tokamak plasma operation with the normalized performance approaching the ITER and CFETR regimes.