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Title: First tests of molybdenum mirrors for ITER diagnostics in DIII-D divertor.

Abstract

Abstract not provided.

Authors:
;  [1]; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ;
  1. Sandia National Laboratories, San Diego, CA
Publication Date:
Research Org.:
Sandia National Laboratories San Diego, CA; Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
Sponsoring Org.:
USDOE National Nuclear Security Administration (NNSA)
OSTI Identifier:
1143359
Report Number(s):
SAND2007-0920J
523966
DOE Contract Number:
DE-AC04-94AL85000
Resource Type:
Journal Article
Resource Relation:
Journal Name: Review of Scientific Instruments; Related Information: Proposed for publication in Review of Scientific Instruments.
Country of Publication:
United States
Language:
English

Citation Formats

Wampler, William R., Watkins, Jonathan G., Rudakov, D.L., Boedo, J.A., Moyer, R.A., Litnovsky, A., Phillipps, V., Wienhold, P., Allen, S.L., Fenstermacher, M.E., Groth, M., Lasnier, C.J., Boivin, R.L., Brooks, N.H., Leonard, A.W., West, W.P., Wong, C.P.C., McLean, A.G., Stangeby, P.C., and De Temmerman, G.. First tests of molybdenum mirrors for ITER diagnostics in DIII-D divertor.. United States: N. p., 2007. Web.
Wampler, William R., Watkins, Jonathan G., Rudakov, D.L., Boedo, J.A., Moyer, R.A., Litnovsky, A., Phillipps, V., Wienhold, P., Allen, S.L., Fenstermacher, M.E., Groth, M., Lasnier, C.J., Boivin, R.L., Brooks, N.H., Leonard, A.W., West, W.P., Wong, C.P.C., McLean, A.G., Stangeby, P.C., & De Temmerman, G.. First tests of molybdenum mirrors for ITER diagnostics in DIII-D divertor.. United States.
Wampler, William R., Watkins, Jonathan G., Rudakov, D.L., Boedo, J.A., Moyer, R.A., Litnovsky, A., Phillipps, V., Wienhold, P., Allen, S.L., Fenstermacher, M.E., Groth, M., Lasnier, C.J., Boivin, R.L., Brooks, N.H., Leonard, A.W., West, W.P., Wong, C.P.C., McLean, A.G., Stangeby, P.C., and De Temmerman, G.. Thu . "First tests of molybdenum mirrors for ITER diagnostics in DIII-D divertor.". United States. doi:.
@article{osti_1143359,
title = {First tests of molybdenum mirrors for ITER diagnostics in DIII-D divertor.},
author = {Wampler, William R. and Watkins, Jonathan G. and Rudakov, D.L. and Boedo, J.A. and Moyer, R.A. and Litnovsky, A. and Phillipps, V. and Wienhold, P. and Allen, S.L. and Fenstermacher, M.E. and Groth, M. and Lasnier, C.J. and Boivin, R.L. and Brooks, N.H. and Leonard, A.W. and West, W.P. and Wong, C.P.C. and McLean, A.G. and Stangeby, P.C. and De Temmerman, G.},
abstractNote = {Abstract not provided.},
doi = {},
journal = {Review of Scientific Instruments},
number = ,
volume = ,
place = {United States},
year = {Thu Feb 01 00:00:00 EST 2007},
month = {Thu Feb 01 00:00:00 EST 2007}
}
  • Metallic mirrors will be used in ITER for optical diagnostics working in different spectral ranges. Their optical properties will change with time due to erosion, deposition, and particle implantation. First tests of molybdenum mirrors were performed in the DIII-D divertor under deposition-dominated conditions. Two sets of mirrors recessed 2 cm below the divertor floor in the private flux region were exposed to a series of identical, lower-single-null, ELMing (featuring edge localized modes) H-mode discharges with detached plasma conditions in both divertor legs. The first set of mirrors was exposed at ambient temperature, while the second set was preheated to temperaturesmore » between 140 and 80 degree sign C. During the exposures mirrors in both sets were additionally heated by radiation from the plasma. The nonheated mirrors exhibited net carbon deposition at a rate of up to 3.7 nm/s and suffered a significant drop in reflectivity. Net carbon deposition rate on the preheated mirrors was a factor of 30-100 lower and their optical reflectivity in the wave range above 500 nm was essentially preserved.« less
  • Experimental results from the National Spherical Torus Experiment (NSTX), a medium-size spherical tokamak with a compact divertor, and DIII-D, a large conventional aspect ratio tokamak, demonstrate that the snowflake (SF) divertor configuration may provide a promising solution for mitigating divertor heat loads and target plate erosion compatible with core H-mode confinement in future fusion devices, where the standard radiative divertor solution may be inadequate. In NSTX, where the initial high-power SF experiment were performed, the SF divertor was compatible with H-mode confinement, and led to the destabilization of large ELMs. However, a stable partial detachment of the outer strike pointmore » was also achieved where inter-ELM peak heat flux was reduced by factors 3-5, and peak ELM heat flux was reduced by up to 80% (cf. standard divertor). The DIII-D studies show the SF divertor enables significant power spreading in attached and radiative divertor conditions. Results include: compatibility with the core and pedestal, peak inter-ELM divertor heat flux reduction due to geometry at lower n e, and ELM energy and divertor peak heat flux reduction, especially prominent in radiative D 2-seeded SF divertor, and nearly complete power detachment and broader radiated power distribution in the radiative D 2-seeded SF divertor at P SOL = 3 - 4 MW. A variety of SF configurations can be supported by the divertor coil set in NSTX Upgrade. Edge transport modeling with the multi-fluid edge transport code UEDGE shows that the radiative SF divertor can successfully reduce peak divertor heat flux for the projected P SOL ≃9 MW case. In conclusion, the radiative SF divertor with carbon impurity provides a wider n e operating window, 50% less argon is needed in the impurity-seeded SF configuration to achieve similar q peak reduction factors (cf. standard divertor).« less
  • Local measurements of line emission of either intrinsic or gas puffed impurities will be performed around and below the X point. Such spectroscopic measurements, together with divertor Thomson scattering and bolometric imaging will enable estimates of divertor impurity particle distributions and power losses. A proposed multilayer mirror (MLM) diagnostic mounted inside the tokamak vessel will measure XUV (100{endash}200 {Angstrom}) emission from impurities at multiple locations in the divertor region of the C-Mod tokamak. A prototype of this instrument measuring NV at 162.6 {Angstrom} is scheduled to be installed on C-Mod with a single chordal view of the X point. Amore » multichordal/multispectral device using MLMs and gratings has been designed for the DIII-D tokamak. The instrument will measure the resonance emission of CII to CVI from 40{endash}2000 {Angstrom}, thus enabling a more direct and reliable estimate of the impurity content in the divertor. At DIII-D, the device will be mounted on a port below the mid plane avoiding spectroscopic contamination from the core plasma. {copyright} {ital 1997 American Institute of Physics.}« less
  • The DIII-D tokamak is being upgraded to allow for divertor biasing, baffling, and pumping experiments. This paper gives an overview of the new diagnostics added to DIII-D as part of this advanced divertor program. They include tile current monitors, fast reciprocating Langmuir probes, a fixed probe array in the divertor, fast neutral pressure gauges, and H{sub {alpha}} measurements with TV cameras and fiber optics coupled to a high-resolution spectrometer.