Pedestal Structure in DIII-D Steady-State Discharges

A range of DIII-D steady-state discharges have been analyzed to determine the pedestal structure and bootstrap current as a function of several global parameters including $q_{min}$, $q_{95}$ and $\beta_N$. The pedestal structures are compared with EPED predictions. Variations in turbulence, $E\times B$ shearing rate, $j_{BS}$ and MHD stability are examined. DIII-D is developing candidate high-$\beta_N$ steady-state operational scenarios, including high-$q_{min}$ and high-$\ell_i$, through current and pressure profile optimization. Pedestal structure and how it affects the current profile is important for any sustained high performance scenario. High-$q_{min}$ scenarios require a relatively large pedestal height with significant bootstrap current, while high-$\ell_i$ scenarios require a smaller pedestal and reduced bootstrap current. Understanding how the pedestal structure is affected by the other requirements of operating in these scenarios is needed for this optimization.