Deuterium Atomic and Molecular Radiation in DIII-D high-recycling divertor plasmas

EIRENE predictions of emission from the deuterium Lyman series and molecular bands in DIII-D high-recycling divertor plasmas show that Lyman-a emission is approximately an order of magnitude stronger than the Lyman-Werner molecular bands, indicating that emission from molecules plays a secondary role in the divertor radiation power balance. The underlying deuterium-carbon plasma, calculated by EDGE2D-EIRENE and serving as the basis for this assessment, electron temperatures of 1 eV at the low-field target plate are predicted as measured. The simulations, however, under-predict the measured electron density by a factor of 2 to 3, and thus the atomic and molecular densities. The impact of the magnitudes and spatial distributions of the plasma profiles on divertor deuterium emission is discussed.