Transport modeling of NSTX plasmas with TGLF reduced transport model

The TGLF reduced transport model is being validated against core profiles in L/H-mode plasmas from NSTX for use as a predict-first tool for future scenario development on NSTX-U. In a low beta L-mode discharge, where ETG/ITG instabilities are expected to be dominant, heat-flux-matching TGYRO predictions of plasma temperature profiles are in a good agreement with experimental data. TGLF simulations at multiple radii indicate that the contribution of low-ky ion scale modes to electron heat transport can reach up to 80% of the total flux in the ITG unstable region. Ion heat flux in this shot is predicted to have a comparable fraction of neoclassical and turbulent contributions. This is different compared to H-mode discharges with higher plasma density and beta, where simulations show fully neoclassical ion heat flux. In H-mode shots a discrepancy between predicted electron temperature and measurements is observed inside the region ρ ∼ 0.5−0.7 and potentially can be caused by MTM instabilities unresolved by TGLF model. To deepen the understanding of what drives the heat transport in the core region of NSTX, we will verify the critical inverse temperature gradients predicted by TGLF against gyro-kinetic simulations.

Work supported by US DOE under DE-SC0021113 and DE-AC02-09CH11466.