New high resolution kinetic equilibrium for the DIII-D discharge 132014.03000

Rich has sent an updated EFIT equilibrium for the DIII-D discharge 132014.03000. It has resolution of 129×129, kinetic equilibrium option enable and low EFIT error parameter. The TEQ code shows significantly lower residual in the near separatrix region as well.

Note that the plasma pressure profiles looks significantly different comparing to the lower resolution case at 3.023 sec (left figure below shows the derivate of the plasma pressure at 3.000 sec and right figure shows the derivative of the plasma pressure at 3.023 sec):


EFIT code has been run with higher resolution for the DIII-D equilibrium 132014.03023

EFIT grid has been set to 129×129, number of iterations has been increased to 50, the namelist value for error has been decreased from 1.e-3 to 1.e-4. The resulting layout looks very similar. However, the normalized beta is reduced by about 3%. Analysis with TEQ still indicates relatively high residual error near the separatrix. This error might be related to different input options that might be associated with different account for the bootstrap current. There are differences in FF’ and q profiles that might be more difficult to understand. Some of equilibrium profiles are shown below. Left column shows profiles obtained with the new EFIT (129×129) run, while the left column shows profiles obtained with the old EFIT (65×65) run.


XGC-A04: Increased particle transport in the SOL region

The particle diffusivity in the outside separatrix region has been increased from 0.05 to 0.5 m^2/sec:

tbl_D_coeff2=0.5D0     ! m^2/sec, D_turb for outside of separatrix (SOL+private flux region)

The resulting plasma density profile is identical to the profile obtained in the case XGC-A03.

This problem is likely related to a mistake in the particle diffusivity implementation in the SOL region.


XGC-A03: Gradients for initial temperature profiles in the plasma core are increased

There are two changes comparing to the case XGC-A02:

  1. Gradients for initial temperature profiles in the plasma core are increased in order to see profile change at earlier times;
  2. The parameter neu_grid_min_psi is used in the namelist and is set to 0.75 in order to extend the region where the neutral distribution is computed.


XGC-A02: Case identical to XGC-A01 but 5 times longer simulation

Problems identified in the case XGC-A02 remains at longer times (30 ion transit times in the case XGC-A02 vs 6 ion transit times in the case XGC-A01). The diffusivity remain rather high in the plasma core. Particles accumulate in the SOL region. It looks that the later problem has been introduced during recent code update and relates to the interpolation of tbl_* diffusivities used in the outer region of plasma and FMCFM diffivities in the plasma core.