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Photon Trapping Effects in DEMO Divertor Plasma
Author(s) -
Hoshino K.,
Sawada K.,
Idei R.,
Tokunaga S.,
Asakura N.,
Shimizu K.,
Ohno N.
Publication year - 2016
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.201610039
Subject(s) - divertor , plasma , atomic physics , ionization , trapping , radiation trapping , electron density , photon , electron , radiative transfer , physics , electron temperature , ion , nuclear physics , optics , radiation , tokamak , ecology , quantum mechanics , biology
In the DEMO divertor, the neutral density becomes high to produce the full detachment and therefore the photon trapping can become important. In this paper, effects of the photon trapping on the DEMO divertor plasma has been studied. The pre‐evaluation of the photon trapping effects on the fixed background plasma profile was carried out by using an iterative self‐consistent collisional radiative model. The recombining plasma near the inner target and the private region changed to the ionizing plasma by the photon‐excitation. Based on the preevaluation result, the database of the effective ionization rate coefficient including the photon transport inside a 2 mm sphere. Advantage of the 2 mm sphere approximation is that the extra calculation cost is not necessary. Iterative calculation of the SONIC including the photon trapping effects was carried out. While the electron density increased and the neutral density decreased in the wide region, the electron density decreases close to the inner strike point. This may be due to decrease in the ionization rate by decrease in the neutral density. (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)