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Measurements of large poloidal variations of impurity density in the Alcator C-Mod H-mode barrier region.
- Source :
- Physics of Plasmas; Oct2002, Vol. 9 Issue 10, p4188, 5p
- Publication Year :
- 2002
-
Abstract
- Simultaneous high resolution measurements of the soft x-ray emission at the top and outboard edge of the Alcator C-Mod tokamak [I. H. Hutchinson et al., Phys. Plasmas 1, 1511 (1994)] are presented. Impurity density profiles are derived from these measurements. The impurity density varies considerably on a flux surface in the high confinement mode (H-mode) pedestal region. The soft x-ray and impurity density pedestals are not on the same flux surface at the top and outboard edge. The pedestal widths are consistently larger at the outboard edge in the Enhanced D-alpha (EDA) H-mode, suggesting a ballooning-like character of the EDA quasi-coherent mode. The usual separation of time scales between radial and parallel impurity transport does not hold in the H-mode pedestal region of Alcator C-Mod. Thus, one should not necessarily expect that the impurity density be constant on a flux surface in this region. [ABSTRACT FROM AUTHOR]
- Subjects :
- X-ray spectroscopy
TOKAMAKS
PLASMA gases
IMPURITY distribution in semiconductors
Subjects
Details
- Language :
- English
- ISSN :
- 1070664X
- Volume :
- 9
- Issue :
- 10
- Database :
- Complementary Index
- Journal :
- Physics of Plasmas
- Publication Type :
- Academic Journal
- Accession number :
- 7364829
- Full Text :
- https://doi.org/10.1063/1.1506162