Advances towards high performance low-torque $q_{min} > 2$ operations with large-radius ITB on DIII-D

A joint DIII-D/EAST experiment was performed aimed at extending a fully noninductive scenario with high $\beta_P$ and $q_{min} > 2$ to inductive operation at lower torque and higher I$_p$ (0.6 $\rightarrow$ 0.8 MA) for better performance. Extremely high confinement was obtained, i.e., H$_{98y2}$ $\sim$ 2.1 at $\beta_N \sim$ 3, which was associated with a strong ITB at large minor radius ($\rho\sim$ 0.7). Alfv\'en Eigenmodes and broadband turbulence were significantly suppressed in the core, and fast-ion confinement was improved. ITB collapses at 0.8 MA were induced by ELM-triggered n = 1 MHD modes at the ITB location, which is different from the ``relaxation oscillations'' associated with the steady-state plasmas at lower current (0.6 MA). This successful joint experiment may open up a new avenue towards high performance low-torque $q_{min} > 2$ plasmas with large-radius ITBs, which will be demonstrated on EAST in the near future.