skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

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

Abstract

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.

Authors:
 [1];  [1];  [1];  [1];  [1];  [1];  [1];  [1];  [1];  [2]
  1. Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)
  2. Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States) (and others)
Publication Date:
OSTI Identifier:
20216060
Resource Type:
Journal Article
Journal Name:
Physics of Plasmas
Additional Journal Information:
Journal Volume: 7; Journal Issue: 5; Other Information: PBD: May 2000; Journal ID: ISSN 1070-664X
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; PLASMA IMPURITIES; ALCATOR DEVICE; NEUTRAL-PARTICLE TRANSPORT; PLASMA CONFINEMENT; BOUNDARY LAYERS; ENERGY LOSSES; PLASMA DENSITY; DEUTERIUM; IONIZATION; PLASMA DIAGNOSTICS; 1-NITROSO-2-NAPHTHOL; TEMPERATURE MEASUREMENT; CHARGE EXCHANGE; HEAT TRANSFER; POWER LOSSES; EXPERIMENTAL DATA

Citation Formats

Boivin, R. L., Goetz, J. A., Hubbard, A. E., Hughes, J. W., Hutchinson, I. H., Irby, J. H., LaBombard, B., Marmar, E. S., Mossessian, D., and Pitcher, C. S. Effects of neutral particles on edge dynamics in Alcator C-Mod plasmas. United States: N. p., 2000. Web. doi:10.1063/1.874016.
Boivin, R. L., Goetz, J. A., Hubbard, A. E., Hughes, J. W., Hutchinson, I. H., Irby, J. H., LaBombard, B., Marmar, E. S., Mossessian, D., & Pitcher, C. S. Effects of neutral particles on edge dynamics in Alcator C-Mod plasmas. United States. doi:10.1063/1.874016.
Boivin, R. L., Goetz, J. A., Hubbard, A. E., Hughes, J. W., Hutchinson, I. H., Irby, J. H., LaBombard, B., Marmar, E. S., Mossessian, D., and Pitcher, C. S. Mon . "Effects of neutral particles on edge dynamics in Alcator C-Mod plasmas". United States. doi:10.1063/1.874016.
@article{osti_20216060,
title = {Effects of neutral particles on edge dynamics in Alcator C-Mod plasmas},
author = {Boivin, R. L. and Goetz, J. A. and Hubbard, A. E. and Hughes, J. W. and Hutchinson, I. H. and Irby, J. H. and LaBombard, B. and Marmar, E. S. and Mossessian, D. and Pitcher, C. S.},
abstractNote = {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.},
doi = {10.1063/1.874016},
journal = {Physics of Plasmas},
issn = {1070-664X},
number = 5,
volume = 7,
place = {United States},
year = {2000},
month = {5}
}