Determination of the electron cyclotron current drive profile

Evaluation of the profile of non-inductive current density driven by absorption of electron cyclotron waves (ECCD) using time evolution of the poloidal flux indicated a broader profile than predicted by theory. To determine the nature of this broadening, a 1-1/2 D transport calculation of current density evolution was used to generate the signals which the DIII-D motional Stark effect (MSE) diagnostic would measure in the event that the current density evolution followed the neoclassical Ohmʹs law with the theoretical ECCD profile. Comparison of the measured MSE data with the simulations indicates the experimental data is consistent with the narrow ECCD profile predicted by theory. The simulations indicate the magnitude of the ECCD is at or above the value found in Fokker–Planck calculations of the ECCD, which includes quasilinear and parallel electric field effects.