Particle, heat, and sheath power transmission factor profiles during ELM suppression experiments on DIII-D

Edge localized modes (ELMs) are predicted to be a significant problem for ITER due to impulse heating of the divertor target plates. During low collisionality experiments on DIII-D where ELMs were suppressed using resonant magnetic perturbations (RMP), target plate profiles of particle flux (J_sat), electron temperature (T_e), and floating potential (V_f) have been measured with Langmuir probes (LP) and compared to IRTV heat flux profiles. During ELM suppression, J_sat and T_e increase and the J_sat profile broadens. A three-peak structure, most visible in the V_f, agrees with the spacing and q₉₅ dependence of an n = 3 toroidal pattern predicted by the TRIP3D code. The heat flux calculated from Langmuir probe data (using sheath theory) is observed to get ∼2× larger during ELM suppression than between ELMs before the RMP is turned on. The sheath power transmission factor profile has been determined from IRTV and Langmuir probe data.