Measurements of molybdenum radiation in the Alcator C-Mod tokamak using a multilayer mirror soft x-ray polychromator

Journal Article · Sun Jan 01 04:00:00 EST 1995 · Review of Scientific Instruments; (United States)

DOI:https://doi.org/10.1063/1.1146352· OSTI ID:7060130

May, M J; Finkenthal, M; Regan, S P; Moos, H W ^[1]; Terry, J L; Graf, M A ^[2]; Fournier, K; Goldstein, W L ^[3]

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1. Department of Physics and Astronomy, The Johns Hopkins University, Baltimore, Maryland 21218 (United States)
2. Plasma Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)
3. Lawrence Livermore National Laboratory, Livermore, California 94551 (United States)

A photometrically calibrated polychromator utilizing layered synthetic microstructure coated flats (also known as multilayer mirrors, MLMs) as dispersive elements is operating on the Alcator C-Mod tokamak to measure the molybdenum emissions in the XUV. Molybdenum, the first wall material in C-Mod, is the dominant high [ital Z] impurity in the plasma. Three spectral regions are measured by three separate MLM-detector channels. The characteristic charge states in the region between 30--40 A are Mo XV to Mo XX, between 65--90 A are Mo XXIV to Mo XXVI, and between 110--130 A are Mo XXXI and Mo XXXII. The instrument's spectral resolution varies from 0.4 A at [lambda]=30 A to 7 A at [lambda]=130 A. The temporal resolution is typically 1.0 ms, but sampling rates of less than 1 ms are possible. The instrument was photometrically calibrated at The Johns Hopkins University using a Manson soft x-ray light source. Power loss estimates from Mo XXIV to Mo XXVI, Mo XXXI, and Mo XXXII have been obtained during ohmic and ICRF plasmas using the MIST transport code to model the molybdenum charge state distributions in the plasma. The Mo concentrations have also been determined. Mo contributes [similar to]0.1 to the [ital Z][sub eff] of 1.3 during ohmic plasmas. This contribution increases during ICRF heating to [similar to]0.5 of the [ital Z][sub eff] of 2. The polychromator functions as a time-resolved soft x-ray emission power loss monitor.

• DOE Contract Number: FG02-86ER53214; AC02-78ET51013
• OSTI ID: 7060130
• Journal Information: Review of Scientific Instruments; (United States), Journal Name: Review of Scientific Instruments; (United States) Vol. 66:1; ISSN 0034-6748; ISSN RSINAK
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
700320* -- Plasma Diagnostic Techniques & Instrumentation-- (1992-)
700330 -- Plasma Kinetics
Transport
& Impurities-- (1992-)
700410 -- Specific Fusion Devices & Experiments-- (1992-)
ALCATOR DEVICE
CALIBRATION
CHARGED PARTICLES
CLOSED PLASMA DEVICES
EXTREME ULTRAVIOLET SPECTRA
IMPURITIES
IONS
MEASURING INSTRUMENTS
MOLYBDENUM IONS
MULTICHARGED IONS
PLASMA DIAGNOSTICS
PLASMA IMPURITIES
SPECTRA
SPECTROMETERS
THERMONUCLEAR DEVICES
TOKAMAK DEVICES
ULTRAVIOLET SPECTRA
X-RAY SPECTROMETERS