Improving the XGC0 modeling of the Alcator C-Mod discharge 1120815027

A better combination of anomalous transport coefficients have been found to match the experimental profiles in the Alcator C-Mod discharge 1120815027 (runid # xcmod-a37):
Electron temperature profileIon temperature profilePlasma density profile
These results can be compared with old simulation results given in .
Note, that the electron and ion temperature profiles looks different (the experimental profiles are identical). The resulting bootstrap current profile looks as
Bootstrap current
The width and maximum value of the localized peak in the poloidal rotation have changed significantly:
Poloidal velocity

Neoclassical transport in the Alcator C-Mod discharge 1120815027

Following a request from Ahmed Diallo, I have started the analysis of the Alcator C-Mod discharge 1120815027. The objective if this study is to compute the neoclassical transport at the plasma edge of this discharge and to compare the neoclassical coefficients with some known analytical formulas. After usual several short XGC0 simulations, I was able to reconstruct the anomalous transport coefficients that are needed to match the simulated density profiles with the experimental profiles. There is still some work that is needed to match the temperature profiles. Here is the summary of plasma profiles that are computed so far (case xcmod.a27):
Electron density / Electron and ion temperatures

Electron density Electron and ion temperatures

Toroidal and poloidal velocities
Toroidal velocity jboot-10

Effective neoclassical diffusivites
Effective neoclasical diffusivities
Thermal fluxes
Ion thermal fluxes Electron thermal fluxes

Radial electric field and bootstrap current
Radial electric field Bootstrap current

Particle fluxes
Particle fluxes

Here, HH stands for the Hinton-Hazeltine formulas for the bootstrap current and the radial electric field.

These results were discussed with Ahmed and it has been decided that the toroidal and possible poloidal rotation profiles need to be compared with the experimental data from Alcator C-Mod. However, because most of measurements are for impurities, it will be necessary to rerun the XGC0 code with impurities. I will need to update the code either from Devon or somebody else from the CS group.

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.