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Author Brooks, J. N.
Source United States Department of Energy Office of Scientific and Technical Information
Content type Text
Language English
Subject Keyword PLASMA PHYSICS AND FUSION ♦ ITER TOKAMAK ♦ PLASMA IMPURITIES ♦ RARE GASES ♦ NEON ♦ ARGON ♦ DIVERTORS ♦ DEUTERIUM ♦ TRITIUM ♦ BERYLLIUM ♦ CARBON ♦ TUNGSTEN ♦ THERMONUCLEAR DEVICES ♦ PLASMA SCRAPE-OFF LAYER
Abstract Near-surface recycling of neon and argon atoms and ions at a divertor has been studied using impurity transport and surface interaction codes. A fixed background deuterium{endash}tritium plasma model is used corresponding to the International Thermonuclear Experimental Reactor (ITER) [{ital ITER} {ital EDA} {ital Agreement} {ital and} {ital Protocol} 2, ITER EDA Documentation Series No. 5 (International Atomic Energy Agency, Vienna, 1994)] radiative plasma conditions ({ital T}{sub {ital e}}{le}10 eV). The noble gas transport depends critically on the divertor surface material. For low-{ital Z} materials (Be and C) both neon and argon recycle many (e.g., {approximately}100) times before leaving the near-surface region. This is also true for an argon on tungsten combination. For neon on tungsten, however, there is low recycling. These variations are due to differences in particle and energy reflection coefficients, mass, and ionization rates. In some cases a high flux of recycling atoms is ionized within the magnetic sheath and this can change local sheath parameters. Due to inhibited backflow, high recycling, and possibly high sputtering, noble gas seeding (for purposes of enhancing radiation) may be incompatible with Be or C surfaces, for fusion reactor conditions. On the other hand, neon use appears compatible with tungsten. {copyright} {ital 1996 American Institute of Physics.}
ISSN 1070664X
Educational Use Research
Learning Resource Type Article
Publisher Date 1996-06-01
Publisher Place United States
Journal Physics of Plasmas
Volume Number 3
Issue Number 6


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