Validating gyrokinetic simulations of TCV negative triangularity plasmas

Gyrokinetic edge and SOL simulations of inner-wall limited discharges on TVC of positive and negative triangularity demonstrate good agreement with experimental data. The Gkeyll code has been used to carry out gyrokinetic 2D axisymmetric and 3D turbulence simulations to explore the interplay of triangularity and neutral physics on profile formation and turbulence. The axisymmetric formulation includes a diffusion coefficient in phase space to model radial turbulent transport. Scans of the radial diffusion coefficient demonstrate a stronger effect on density profiles relative to temperature profiles, as expected. Neutrals are also included using a continuum kinetic model for neutral transport with atomic reaction rates for ionization and recombination taken from the Open-ADAS database. The effect of these collisions and triangularity on trapped particle fraction is explored, demonstrating the importance of including atomic neutral physics to obtain more realistic profiles. Finally, initial results from 3D turbulence simulations of these discharges are compared with experimental fluctuation data. These validation efforts build confidence in the predictive capability of the Gkeyll code in our progression to more reactor relevant scenarios.

This material is based upon work supported by the US DOE, Office of Science, Office of Fusion Energy Sciences, through the CEDA SciDAC Award No. DE-AC02-09CH11466 and DE-SC0010529.