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Investigation of dust shielding effect of intrinsic ergodic magnetic field line structures in the peripheral plasma in the large helical device
Author(s) -
Shoji M.,
Kawamura G.,
Smirnov R.D.,
Pigarov A. Yu.,
Tanaka Y.,
Masuzaki S.,
Uesugi Y.
Publication year - 2018
Publication title -
contributions to plasma physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.531
H-Index - 47
eISSN - 1521-3986
pISSN - 0863-1042
DOI - 10.1002/ctpp.201700125
Subject(s) - large helical device , plasma , divertor , electromagnetic shielding , atomic physics , magnetic field , materials science , plasma parameters , physics , tokamak , nuclear physics , composite material , quantum mechanics
Recent long pulse discharges in the large helical device (LHD) have been interrupted by radiation collapse induced by the emission of dust from the surface of the vacuum vessel and the divertor region. The dust shielding effect by intrinsic ergodic magnetic field line structures (ergodic layer) formed around the main plasma confinement region is investigated using a three‐dimensional peripheral plasma fluid code (EMC3‐EIRENE) coupled with a dust transport simulation code (DUSTT). Simulations performed in three different magnetic configurations with narrow, medium, and wide ergodic layers show that the wide ergodic layer is not always effective in shielding the main plasma from the dust emission. Optimum operational regimes for controlling the influence of the dust emission on the sustainment of plasma discharges are found by investigating the impurity ion content in the peripheral plasma for various plasma heating powers and plasma densities in the three magnetic configurations.