Role of Neoclassical Convection in the Confinement Improvement of Plasmas withImpurity Injection in DIII-D

摘要

It was concluded in a previous analysis of the DIII-D experiments that inwardconvection of particles and/or momentum plays a role in the improvement of energy confinement with increasing neon injection. In a separate analysis, we have calculated for the same set of DIII-D experiments that the inward neoclassical main ion flux increases with increasing neon injection, producing an inward convective momentum flux which is of the right magnitude to account for the observed increase in central toroidal rotation velocity and improvement in momentum confinement with increasing neon injection. This result motivates us to investigate the effect of convective transport on the increase in energy confinement time with increasing neon concentration that is observed in this series of DIII-D experiments, which is the purpose of this paper.