Toroidally symmetric/asymmetric effect on the divertor flux due to neon/nitrogen seeding in LHD

•Toroidal distributions of divertor particle flux during Ne and N2 seeded discharges were investigated with Langmuir probe arrays in LHD.•Toroidally quasi-uniform reduction was observed in the Ne seeded discharge.•The N2 seeding induced a toroidally asymmetric effect, being strongly related to the magnetic field structure around the N2 puffing port.•EMC3-EIRENE simulation under the partially-recycling condition shows local effects similar to the N2 seeded experiment. Toroidal distributions of divertor particle flux during neon (Ne) and nitrogen (N2) seeded discharges were investigated in the Large Helical Device (LHD). By using 14 toroidally distributed divertor probe arrays, which were positioned at radially inner side where the divertor flux concentrates in the inward-shifted magnetic axis configuration, it is found that Ne puffing leads to toroidally quasi-uniform reduction of divertor particle fluxes; whereas toroidally localized reductions were observed with N2 puffing. The toroidally asymmetric reduction pattern with N2 puffing is strongly related to the magnetic field structure around the N2 puffing port. Assuming that nitrogen particles do not recycle, EMC3-EIRENE simulation shows similar reduction pattern with the experiment around the N2 puffing port.