A New Path to Improve High \beta_\rm p Plasma Performance on EAST for Steady-State Tokamak Fusion Reactor

High \beta_\rm 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 \nabla n is a control knob to improve energy confinement in high \beta_\rm p plasmas at low toroidal rotation as projected for a fusion reactor. Different from previously known turbulent stabilization mechanisms such as \boldsymbol E \times \boldsymbol B shear and Shafranov shift, high density gradient can enhance the Shafranov shift stabilizing effect significantly in high \beta_\rm 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_\rm p scenario. It has been demonstrated in the recent EAST experiments, i.e., a fully non-inductive high \beta_\rm p (\sim 2) H-mode plasma (H_98y2\ge 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.