Effects of neutral particles on edge dynamics in Alcator C-Mod plasmas

Journal Article · Mon May 01 00:00:00 EDT 2000 · Physics of Plasmas

DOI:https://doi.org/10.1063/1.874016· OSTI ID:20216060

Boivin, R L ^[1]; Goetz, J A ^[1]; Hubbard, A E ^[1]; Hughes, J W ^[1]; Hutchinson, I H ^[1]; Irby, J H ^[1]; LaBombard, B ^[1]; Marmar, E S ^[1]; Mossessian, D ^[1]; Pitcher, C S ^[1]

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1. Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)

Neutral particle densities and energy losses have been measured in the Alcator C-Mod tokamak [Hutchinson et al., Phys. Plasmas 1, 1511 (1994)]. Their effect on the formation and evolution of the edge barrier which accompanies the enhanced confinement regime are discussed. The neutrals can enter the edge dynamics through the particle, momentum, and energy balance. Neutral densities of up to 5x10{sup 16} m{sup -3} have been measured in the edge barrier region. Neutrals enter the local dynamics around most of the periphery, not just at the X-point. High resolution measurements of the ionization profile have been obtained for the region near the separatrix. The profile shifts inside the separatrix as the plasma is making a transition from low-to high-mode confinement (H-mode) regimes, partly accounting for the dramatic rise in edge density. The measured neutral density is large enough to affect the bulk ion momentum by charge exchange, and thereby introduces a negative radial electric field at the edge. At the same time, significant edge heat flux, carried by the neutrals, contributes to the measured power loss. At very high edge densities, this loss mechanism could contribute to quenching H-modes. (c) 2000 American Institute of Physics.

• OSTI ID: 20216060
• Journal Information: Physics of Plasmas, Journal Name: Physics of Plasmas Journal Issue: 5 Vol. 7; ISSN PHPAEN; ISSN 1070-664X
• Country of Publication: United States
• Language: English

Related Subjects

1-NITROSO-2-NAPHTHOL
70 PLASMA PHYSICS AND FUSION TECHNOLOGY
ALCATOR DEVICE
BOUNDARY LAYERS
CHARGE EXCHANGE
DEUTERIUM
ENERGY LOSSES
EXPERIMENTAL DATA
HEAT TRANSFER
IONIZATION
NEUTRAL-PARTICLE TRANSPORT
PLASMA CONFINEMENT
PLASMA DENSITY
PLASMA DIAGNOSTICS
PLASMA IMPURITIES
POWER LOSSES
TEMPERATURE MEASUREMENT