Progress in gyrokinetic validation studies using NBI heated L-mode discharge in KSTAR

Abstract

Progress in the first gyrokinetic validation study using KSTAR NBI heated L-mode discharge is reported in this paper. The energy flux levels simulated from gyrokinetic code, CGYRO[J. Candy et al., J. Comput. Phys. 324, 73-93 (2016)] were compared with experimental levels in this study for validation purposes. The linear stability analysis indicates that trapped electron modes (TEM) are the most unstable ion-scale modes at r/a = 0.5. The simulated energy flux was under-predicted compared to the experimental energy flux level within their uncertainties. We also observed that simulated energy flux levels were sensitive to the input parameters related to impurity density profile such as effective charge, Z(eff), and inverse gradient scale length of impurity and main ion, a/L-nc and a/L-ni, respectively. For the conclusive future validation studies, we identified the Z(eff) profile, which can give constraints on not only impurity but also main ion profiles, as necessary input.