Assessing the Near Edge Transport Mechanisms in Negative and Positive Triangularity Plasmas Using QLGYRO

Negative triangularity (NT) scenarios are a promising candidate for fusion reactors due to their high confinement and absence of edge-localized modes. However, predictive modeling of NT plasmas remains challenging, particularly near the edge where conventional core transport models lose validity and robust physics-based models are lacking in NT. To address this gap, we extend the core predictive capabilities of the FUsion Synthesis Engine (FUSE) toward the edge of NT plasmas using the quasilinear gyrokinetic code QLGYRO. QLGYRO provides a balance between accuracy and efficiency by combining high-fidelity linear growth rates from the gyrokinetic code CGYRO with the simplified saturation rules of the quasilinear Gyro-Landau Fluid model TGLF. We focus on identifying the limiting microturbulent instabilities near the edge, where QLGYRO can effectively capture the linear stability of kinetic ballooning modes, which are believed to play a key role in NT edge transport. To support fast and reliable predictions, a QLGYRO-based surrogate model (GKNN) is verified against high-fidelity calculations. A parallel analysis is conducted for positive triangularity (PT) plasmas to compare and contrast the transport behavior between NT and PT scenarios.