Onset of Detachment in the DIII-D Closed Divertor for an n = 3 Resonant Magnetic Perturbation*

A stable solution for detachment during resonant magnetic perturbation (RMP) application has been achieved in EMC3-EIRENE for the closed divertor at DIII-D. For this work, the particle flux rollover which indicates the onset of detachment in the closed divertor is determined for a discharge with an n = 3 perturbation at high plasma densities and H-Mode. EMC3-EIRENE has the capability to model detachment scenarios by linearizing the electron energy sink term from the neutral gas interaction. Plasma response from the MARS-F code is used as an input for the magnetic equilibrium and the RMP current amplitude is varied to determine its effect on the scrape-off layer (SOL) plasma. The plasma is modeled with an input power into the SOL of 5.5 MW, and chemically sputtered carbon impurities. Spatially uniform anomalous diffusion of the main ion species and impurities are defined as 0.3 m²/s, and energy diffusivity is 1 m²/s.  The present modeling suggests that the detachment rollover for the upper closed divertor in the presence of an n = 3 perturbation occurs for a control parameter of the deuterium puffing rates ~ 290 Torr-L/s (220 Torr-L/s in this experiment). These background scrape-off layer plasma solutions will then be used in ERO2.0 to determine the characteristics of carbon transport during H-Mode in a resonant magnetic perturbation scenario for a changing magnetic footprint.