Impurity transport in Alcator C-Mod plasmas

Journal Article · Thu May 01 04:00:00 EDT 1997 · Physics of Plasmas

DOI:https://doi.org/10.1063/1.872291· OSTI ID:561114

Rice, J E; Terry, J L; Goetz, J A; Wang, Y; Marmar, E S; Greenwald, M; Hutchinson, I; Takase, Y; Wolfe, S; Ohkawa, H; Hubbard, A ^[1]

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1. Plasma Fusion Center, Massachusetts Institute of Technology, 175 Albany St., Cambridge, Massachusetts 02139-4307 (United States)

Trace non-recycling impurities have been injected into Alcator C-Mod [I. H. Hutchinson {ital et al.}, Phys. Plasmas {bold 1}, 1511 (1994)] plasmas in order to determine impurity transport coefficients. Subsequent impurity emission has been observed with spatially scanning x-ray and Vacuum Ultra-Violet (VUV) spectrometer systems. Measured time-resolved brightness profiles of helium- and lithium-like transitions have been compared with those calculated from a transport code which includes impurity diffusion and convection in conjunction with an atomic physics package for individual line emission. During Low-Confinement-Mode (L-mode) plasmas, the transport can be characterized by pure diffusion, with coefficients {approximately}5000 cm{sup 2}/s, reflecting the {approximately}20 ms decay in the x-ray and VUV line brightnesses. During High-Confinement-Modes (H-modes), the impurity confinement times are much longer, and the modelling requires that there be a strong inward convection (of order 1000 cm/s) near the plasma edge, with greatly reduced diffusion (of order 100 cm{sup 2}/s), also in the region of the edge transport barrier. These edge values of the transport coefficients during H-mode are qualitatively similar to the neo-classical values. Nitrogen has also been injected, and after the H- to L-mode transition, the inner shell satellite lines of lithium-like nitrogen dominate in intensity the resonance line of helium-like N{sup 5+} in a thin shell near the plasma edge. {copyright} {ital 1997 American Institute of Physics.}

• Research Organization: Massachusetts Institute of Technology
• DOE Contract Number: AC02-78ET51013
• OSTI ID: 561114
• Report Number(s): CONF-961102--
• Journal Information: Physics of Plasmas, Journal Name: Physics of Plasmas Journal Issue: 5 Vol. 4; ISSN PHPAEN; ISSN 1070-664X
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
ALCATOR DEVICE
BOUNDARY LAYERS
DIFFUSION
EMISSION SPECTRA
FAR ULTRAVIOLET RADIATION
H-MODE PLASMA CONFINEMENT
MASS TRANSFER
MULTICHARGED IONS
NITROGEN IONS
PLASMA DIAGNOSTICS
PLASMA IMPURITIES
PLASMA RADIAL PROFILES
X RADIATION