Integrated simulation and instability analysis of drift wave turbulence for the hot ion mode on HL-3 tokamak

Abstract A hot ion mode with T i (0) > 10 keV, T i (0)/T e (0) ≈ 2.4, and fusion triple product 0.65 × 10 20 m −3 · keV · s has been achieved on HL-3. Integrated OMFIT modeling across three time slices (pre-H-mode, H-mode, L-mode) reproduces experimental profiles and reveals two distinguishing physics features. First, the ITB foot extends beyond qmin, in contrast to conventional strong reversed shear regimes where the barrier is confined within qmin, here it is sustained by the strong E × B flow shear, the decisive stabilization mechanism. Second, the complete H–L back transition exhibits pronounced ITB hysteresis: the edge transport barrier collapses while the core ITB persists with only 4% width reduction and 3.6% stored energy loss, indicating strong core-edge decoupling. Toroidal rotation dominates the radial electric field (∼−120 kV/m in H-mode, exceeding the diamagnetic term by a factor of 3–6), with its peak aligned with the ITB mid-radius. Within the ITB, E × B shear surpasses the ITG growth rate, suppressing ion transport to near neoclassical levels; at the foot (ρ ≈ 0.6) an ITG to ETG transition occurs near k y ρ s ≈ 1. A T i /T e scan confirms the radial contrast and opposite growth rate scalings. These results establish a validated simulation platform for the HL-3 hot ion mode and support the planned deuterium–tritium campaign.