MLM-based monochromator for molybdenum impurity monitoring on the Alcator C-MOD tokamak in the 30--130 A range

Journal Article · Thu Oct 01 04:00:00 EDT 1992 · Review of Scientific Instruments; (United States)

DOI:https://doi.org/10.1063/1.1143473· OSTI ID:7009204

May, M J; Zwicker, A P; Moos, H W ^[1]; Finkenthal, M ^[2]; Terry, J L ^[3]

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1. Department of Physics and Astronomy, The Johns Hopkins University, Baltimore, Maryland 21218 (United States)
2. Racah Institute of Physics, Hebrew University, Jerusalem (Israel)
3. Plasma Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)

Molybdenum, from the vessel wall armor tiles and divertor plates, is expected to be the dominant high-{ital Z} impurity in the Alcator C-MOD tokamak plasma. To monitor the molybdenum emission in the extreme ultraviolet (XUV), a monochromator utilizing multilayer mirrors (MLMs) as dispersive elements will be installed on the C-MOD tokamak with a 10{degree} above the mid-plane view across the plasma's center. Much of the strong Mo emission under the C-MOD experimental conditions will be emitted between 30--50 A and 65--90 A by {ital M}-shell ions ({ital n}=3--3 and {ital n}=3--4 transitions), at 116 A from MoXXXI and at 127 A from MoXXXII. The monochromator will have three MLMs and either three-channel electron multipliers or three XUV silicon photodiodes mounted on a single {theta}-2{theta} goniometer. Each MLM and detector unit will simultaneously monitor a separate molybdenum emission range with a 1--10-ms temporal resolution. The resolution of the MLMs range from 1 to 5 A depending on the wavelength, and each MLM will be optimized for one of the above spectral regions. This low-resolution monitoring of many charge states will enable radiative power loss estimates and can be used in impurity transport analysis. The design of the monochromator and the expected Mo emission will be presented and discussed.

• DOE Contract Number: FG02-86ER53214
• OSTI ID: 7009204
• Journal Information: Review of Scientific Instruments; (United States), Journal Name: Review of Scientific Instruments; (United States) Vol. 63:10; ISSN RSINA; ISSN 0034-6748
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
700320* -- Plasma Diagnostic Techniques & Instrumentation-- (1992-)
ALCATOR DEVICE
CHARGED PARTICLES
CLOSED PLASMA DEVICES
DESIGN
ELECTROMAGNETIC RADIATION
EXTREME ULTRAVIOLET RADIATION
IMPURITIES
IONS
MOLYBDENUM IONS
MONOCHROMATORS
PLASMA DIAGNOSTICS
RADIATIONS
THERMONUCLEAR DEVICES
TOKAMAK DEVICES
ULTRAVIOLET RADIATION