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.


Simulations for DIII-D discharges 132014, 132016, 132017, and 132018 with theory motivated and imposed ExB flow shear suppression factors

The theory motivated flow shear suppression yields reasonable anomalous transport suppression level as one can see from the comparison below. Left panels show results with theory motivated factor with fm_cexb coefficient equal to 1, while the right panels show results with imposed flow shear factor.

DIII-D discharge 132014

DIII-D discharge 132016

DIII-D discharge 132017

DIII-D discharge 132018

The coefficient might need to be increased somewhat (especially in the SOL region).


XGC-A08/A09: testing changes in the code that related to problems with particle density evolution

Two input files are generated based on XGC-A07 input file: (1) XGC-A08: same equilibrium and same input file, but older version of the code; (2) XGC-A09: same equilibrium, newer version of the code, but older version of the flow shear suppression model. Left panels show results for the case XGC-A08 and right panels show results for the caseXGC-A09

Results clearly indicated that the problemĀ  has been introduced during the recent merge with the svn repository.


XGC-A07: new equilibrium and updated version of the code

The FMCFM changes has been synchronized with the version of the XGC-0 code from the svn repository. Gunyoung committed his changes related to the impurity radial model and get_mid_r bug. Theory motivated coefficient for the flow shear suppression factor is used. The simulation uses high resolution equilibrium provided by Rich Groebner. There are significant changes in the plasma density dynamics. It is not clear if these changes relate to (1) model for flow shear suppression factor; (2) new equilibrium; (3) other changes to the code. In order to isolate the problem, two new simulations are submitted: (1) XGC-A08: same equilibrium and same input file, but older version of the code; (2) XGC-A09: same equilibrium, newer version of the code, but older version of the flow shear suppression model.