Gyrokinetic simulations of KSTAR core perturbations and transport with energetic particles*

The energetic particle (EP) effect on tokamak confinement is a topic with growing attention for high-performance tokamak operation [1]. The EPs are produced by auxiliary heating or fusion reaction. Recent gyrokinetic simulation studies [2,3] have shown that a comprehensive understanding of various interactions among EP, AE, and microturbulence is needed to properly predict confinement. We aim to achieve an understanding of the impact of EP-AE-turbulence interactions on tokamak core confinement by gyrokinetic simulations of a target KSTAR L-mode discharge #21695 using GTC [4] and GKW [5] codes. In the target discharge [6], control of AE activities has been achieved by ECCD which has changed the q-profile. We have identified unstable BAEs in the AE-active phase, with 3/1 kink-like mode at qmin. We have found linearly the most unstable ETG for turbulence in both AE-active and mitigated phases, but it appears to be ineffective on transport compared to the ion-scale modes, TEM for the AE-active phase and ITG for the mitigated phase. Controlled simulations with AE-only and turbulence-only and a comparison with the reference case will be presented, which reveal the impact of AE-turbulence interaction on the confinement.

[1] H. Han et al., Nature 609, 269 (2022)

[2] Di Siena et al., J. Plasma Phys. 87, 555870201 (2021)

[3] P. Liu et al., Phys. Rev. Lett. 128, 185001 (2022)

[4] Z. Lin et al., Science 281, 1835 (1998) 

[5] A.G. Peeters et al., Comput. Phys. Comm. 180, 2650 (2009)

[6] J. Kim et al., Nucl. Fusion 62, 026029 (2022)