Transport modeling of core fueling and global particle confinement in ELM-free H-mode plasma in DIII-D

Abstract

Evaluations of core fueling rates and global particle confinement times are presented for a single-null ELM-free H-mode discharge in the DIII-D tokamak. The edge plasma transport is modeled with the B2.5 code, and the neutral transport with both the DEGAS code and the internal neutrals model in the B2.5 code. Radial transport coefficients and corresponding plasma particle and heat fluxes into the scrape-off layer (SOL) are determined from power balance and by fitting the electron density and temperature profiles measured by Thomson scattering and the ion temperature profiles from charge-exchange/recombination spectroscopy. Divertor plasma parameters are deduced by fitting infrared television camera (IRTV) data, divertor Langmuir probe measurements, and D α data. Core fueling rates are calculated with DEGAS and compared to those required by particle balance, with the core efflux determined by B2.5. Global particle confinement times, deduced at four time slices during the 1.8 s ELM-free period, are typically 3–4 times the corresponding measured energy confinement times.