Three-dimensional impurity transport modeling of neon-seeded and nitrogen-seeded LHD plasmas

Abstract

Modeling of impurity-seeded plasma in Large Helical Device (LHD) is presented for the first time by using the three-dimensional transport code EMC3-EIRENE.High and low recycling coefficients for impurity ions are assumed to include low and high absorption rates on wall surfaces due to low and high chemical activity of neon and nitrogen, respectively.Radiation power measured by two bolometer systems and particle flux measured by divertor probes installed in multiple toroidal sections are utilized to determine impurity amount in the plasma.The toroidal uniformity and the non-uniformity of a divertor flux reduction observed experimentally for neon and nitrogen seeding, respectively, are reproduced by the model.Validations by measurements and deviations between the model and the experiment are discussed.