Simulation of electron thermal transport in H-mode discharges

Electron thermal transport in DIII-D H-mode tokamak plasmas ͓J. L. Luxon, Nucl. Fusion 42, 614 ͑2002͔͒ is investigated by comparing predictive simulation results for the evolution of electron temperature profiles with experimental data. The comparison includes the entire profile from the magnetic axis to the bottom of the pedestal. In the simulations, carried out using the automated system for transport analysis ͑ASTRA͒ integrated modeling code, different combinations of electron thermal transport models are considered. The combinations include models for electron temperature gradient ͑ETG͒ anomalous transport and trapped electron mode ͑TEM͒ anomalous transport, as well as a model for paleoclassical transport ͓J. provides an important contribution near the magnetic axis, which is a region where the ETG mode in the GLF23 model ͓R. E. Waltz et al., Phys. Plasmas 4, 2482 ͑1997͔͒ is below threshold. In simulations of DIII-D discharges, the observed shape of the H-mode edge pedestal is produced when transport associated with the TEM component of the GLF23 model is suppressed and transport given by the paleoclassical model is included. In a study involving 15 DIII-D H-mode discharges, it is found that with a particular combination of electron thermal transport models, the average rms deviation of the predicted electron temperature profile from the experimental profile is reduced to 9% and the offset to Ϫ4%.