Linear and Nonlinear Gyrokinetic Electron Temperature Gradient Mode Simulations for NSTX Discharges and NSTX-U Projections

Experiments on NSTX have demonstrated that electron thermal transport dominates ion thermal transport. One of the modes that is responsible for electron thermal transport is the electron temperature gradient (ETG) mode. A series of NSTX discharges and NSTX-U projections were analyzed to investigate the anomalous electron thermal transport caused by ETG modes. The CGYRO code was employed for this purpose and simulations were carried out in both electrostatic and electromagnetic limits. The results were compared to earlier studies and extended to NSTX-U projections to investigate low collisionality regimes. The gyrokinetic ETGM thermal flux has been utilized to verify and calibrate a recently developed fluid model [1] for electromagnetic toroidal ETG driven drift mode. The fluid ETG model will be used as a component of the Multi-Mode anomalous transport module [2] in the predictive integrated modeling code TRANSP to predict time-dependent electron temperature profiles in NSTX-U and conventional tokamak plasmas.



[1] T. Rafiq et al. Phys. Plasmas, under review for publication (2022)

[2] T. Rafiq et al. Phys. Plasmas 20, 032506 (2013)