TY - JOUR
T1 - Experimental observations and modelling of radiation asymmetries during N2 seeding in LHD
AU - LHD Experiment Group
AU - Peterson, B.J.
AU - Kawamura, G.
AU - van de Giessen, Peter
AU - Mukai, K.
AU - Tanaka, H.
AU - Sano, R.
AU - Pandya, S.N.
AU - Dai, S.Y.
AU - Masuzaki, S.
AU - Akiyama, T.
AU - Kobayashi, M.
AU - Gota, M.
AU - Motojima, G.
AU - Sakomoto, R.
AU - Ohno, N.
AU - Morisaki, T.
AU - Miyazawa, J.
PY - 2021/3/1
Y1 - 2021/3/1
N2 - N2 gas has been seeded in the Large Helical Device (LHD) to reduce the divertor heat load through enhanced radiation. Radiation is observed by two imaging bolometers, viewing the same poloidal cross-section from top and bottom ports, at a location which is 36°toroidally removed from the N2 gas puff nozzle located at the bottom of the machine. During N2 seeding, these measurements both confirm that additional radiation from the outboard side is coming exclusively from the top of the cross-section, indicating up/down asymmetry, which is also reproduced by modelling with EMC3-EIRENE using a half torus model. In addition, a toroidally localized, magnetic field direction-dependent radiation enhancement is observed with N2 seeding, but is not reproducible by the model.
AB - N2 gas has been seeded in the Large Helical Device (LHD) to reduce the divertor heat load through enhanced radiation. Radiation is observed by two imaging bolometers, viewing the same poloidal cross-section from top and bottom ports, at a location which is 36°toroidally removed from the N2 gas puff nozzle located at the bottom of the machine. During N2 seeding, these measurements both confirm that additional radiation from the outboard side is coming exclusively from the top of the cross-section, indicating up/down asymmetry, which is also reproduced by modelling with EMC3-EIRENE using a half torus model. In addition, a toroidally localized, magnetic field direction-dependent radiation enhancement is observed with N2 seeding, but is not reproducible by the model.
KW - Bolometer
KW - Impurity seeding
KW - Magnetic fusion
KW - Plasma
KW - Radiation
UR - http://www.scopus.com/inward/record.url?scp=85098801668&partnerID=8YFLogxK
U2 - 10.1016/j.nme.2020.100848
DO - 10.1016/j.nme.2020.100848
M3 - Article
SN - 2352-1791
VL - 26
SP - 1
EP - 8
JO - Nuclear Materials and Energy
JF - Nuclear Materials and Energy
M1 - 100848
ER -