Kinetic neutral transport effects in the pedestal of H-mode discharges in the DIII-D tokamak

A series of hydrogen and deuterium discharges are analyzed with fluid plasma and Monte Carlo neutrals codes. Comparison of poloidally averaged radial distributions of core neutral density and ionization with analytic solutions of 1-D plasma and neutrals continuity equations support the hypothesis th...

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Bibliographic Details
Published in:Journal of nuclear materials 2005-03, Vol.337-339, p.410-414
Main Authors: Owen, L.W., Groebner, R.J., Mahdavi, M.A.
Format: Article
Language:English
Subjects:
B2.5-DEGAS
DIII-D
Edge modeling
Edge pedestal
Neutral transport
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Summary:A series of hydrogen and deuterium discharges are analyzed with fluid plasma and Monte Carlo neutrals codes. Comparison of poloidally averaged radial distributions of core neutral density and ionization with analytic solutions of 1-D plasma and neutrals continuity equations support the hypothesis that the width of the density pedestal is largely determined by the neutral source. The increased neutral penetration depth that arises from multiple charge exchange can be included in the analytic model with radially dependent scale lengths. The scale length in the analytic model depends on the neutral fluid velocity which increases across the divertor and pedestal as the neutral atoms charge exchange with the higher temperature background ions. The neutral penetration depth and corresponding density pedestal width depend sensitively on the neutral temperature and the degree of ion-neutral temperature equilibration.
ISSN:0022-3115
1873-4820
DOI:10.1016/j.jnucmat.2004.10.033