Diffusivity profiles for anomalous transport are defined

The anomalous diffusivity profiles that can be used in XGC-0 in order to reproduce the experimental profiles in the Alcator C-Mod discharge 1100212024 are finally found. The particle and thermal diffusivity profiles are shown below. Also, the radial electric field, plasma density and total ion temperature are shown as well. It has been found that the ion temperature profile can be reproduced only if the thermal and particle pinches in the pedestal area is introduced. The results are still to be analyzed. There is a small hump in the density profile that is associated with gradient change in the diffusivity profile at around tbl_d_profile_psicen2.

New data for Alcator C-Mod discharge

During the last week, CPES team members (CS, G-Y Park, SH Ku and myself) visited the MIT PSFC. Jerry Hughes and Jim Terry provided eqdsk data and experimental plasma profiles (plasma density and temperatures) for the Alcator C-Mod discharge 1100212024 that represents an identity experiment between Alcator C-Mod and DIII-D. A number of XGC-0 simulations has been run during the visit. The objective of these simulations was to find the diffusivity profiles that can be used in the XGC-0 code in order to reproduce the experimental density and temperature profiles. The eqdsk data has been altered to fit the XGC-0 mesh requirements. The modified eqdsk data are shown on the plot below.

The final diffusivity profiles is identified to have the following shape

It is found that the transition to the SOL anomalous transport occurs in the SOL region rather than in the pedestal region as for DIII-D. The transport levels are still need to be adjusted in order to accurately reproduce the density and [especially] temperature profiles.

It is planned that these simulations will be expended in order to (1) study the heat load on the divertor plates; (2) identify the instabilities that contribute the most to the anomalous transport in this region; (3) study the formation and evolution of radial electric field in the pedestal and SOL regions.