Density measurements in the edge, divertor and X-point regions of Alcator C-Mod from Balmer series emission

Journal Article · Wed Nov 01 04:00:00 EST 1995 · Physics of Plasmas

DOI:https://doi.org/10.1063/1.871049· OSTI ID:172252

Welch, B L; Griem, H R ^[1]; Terry, J; Kurz, C; LaBombard, B; Lipschultz, B; Marmar, E; McCracken, G ^[2]

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1. University of Maryland Institute for Plasma Research, College Park, Maryland 20742-3511 (United States)
2. Massachusetts Institute of Technology Plasma Fusion Center, Cambridge, Massachusetts 02139 (United States)

The electron density in the edge, divertor and X-point regions of Alcator C-Mod [{ital Proceedings} {ital of} {ital the} {ital IEEE} 13{ital th} {ital Symposium} {ital on} {ital Fusion} {ital Engineering} (Institute of Electrical and Electronic Engineers, New York, 1990), Vol. 1, p. 13] has been measured using the Stark broadening of high-{ital n} ({ital n}=8 through 11) transitions of the Balmer series of deuterium. These measurements have been made during typical single null, diverted operation and during gas-puffing through capillaries located within the first wall and divertor. Electron densities up to 1.6{times}10{sup 21} m{sup {minus}3} have been measured in the X-point region and slightly lower densities (5{minus}7{times}10{sup 20} m{sup {minus}3}) have been measured in the divertor and edge regions. These results are factors of 2 to 5 larger than the density measurements from the CO{sub 2} laser interferometer system in the main chamber (3{times}10{sup 20} m{sup {minus}3}) and comparable with probe measurements in the divertor. The ratios of the widths of adjacent lines within the Balmer series have been compared with ratios calculated for the Stark broadening of these lines. These transitions can be used to measure electron densities from 3{times}10{sup 19} to 2{times}10{sup 21} m{sup {minus}3} with a modest resolution spectrograph [({Delta}{lambda}{sub {ital inst}}=1 A full width at half maximum)]. {copyright} {ital 1995} {ital American} {ital Institute} {ital of} {ital Physics}.

• OSTI ID: 172252
• Journal Information: Physics of Plasmas, Journal Name: Physics of Plasmas Journal Issue: 11 Vol. 2; ISSN 1070-664X; ISSN PHPAEN
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
ALCATOR DEVICE
BALMER LINES
DEUTERIUM
DIVERTORS
ELECTRON DENSITY
EMISSION SPECTRA
PLASMA DIAGNOSTICS
PLASMA IMPURITIES
STARK EFFECT
TOKAMAK DEVICES