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Title: Optical dumps for H-alpha and visible spectroscopy in ITER

Abstract

High-reflective Beryllium cover of ITER first wall (R≈30–60%) causes remarkable increase of divertor stray light component (DSL). Optical dumps are well-known solution for DSL attenuation. In this work few types of optical dumps have been examined both by modeling and experimental studies. Taking into account the limitations, induced by ITER first wall design, OD optimized design has been proposed which could decrease divertor stray light component by 10..100 times depending on incidence angle of light.

Authors:
; ; ;  [1]
  1. NRC Kurchatov Institute, 123182 Moscow (Russian Federation)
Publication Date:
OSTI Identifier:
22308286
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 1612; Journal Issue: 1; Conference: International conference on fusion reactor diagnostics, Varenna (Italy), 9-13 Sep 2013; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; ATTENUATION; BERYLLIUM; DESIGN; DIVERTORS; FIRST WALL; INCIDENCE ANGLE; ITER TOKAMAK; MATHEMATICAL SOLUTIONS; SIMULATION; SPECTROSCOPY

Citation Formats

Andreenko, E. N., Alekseev, A. G., Gorshkov, A. V., and Orlovskiy, I. I. Optical dumps for H-alpha and visible spectroscopy in ITER. United States: N. p., 2014. Web. doi:10.1063/1.4894047.
Andreenko, E. N., Alekseev, A. G., Gorshkov, A. V., & Orlovskiy, I. I. Optical dumps for H-alpha and visible spectroscopy in ITER. United States. doi:10.1063/1.4894047.
Andreenko, E. N., Alekseev, A. G., Gorshkov, A. V., and Orlovskiy, I. I. Thu . "Optical dumps for H-alpha and visible spectroscopy in ITER". United States. doi:10.1063/1.4894047.
@article{osti_22308286,
title = {Optical dumps for H-alpha and visible spectroscopy in ITER},
author = {Andreenko, E. N. and Alekseev, A. G. and Gorshkov, A. V. and Orlovskiy, I. I.},
abstractNote = {High-reflective Beryllium cover of ITER first wall (R≈30–60%) causes remarkable increase of divertor stray light component (DSL). Optical dumps are well-known solution for DSL attenuation. In this work few types of optical dumps have been examined both by modeling and experimental studies. Taking into account the limitations, induced by ITER first wall design, OD optimized design has been proposed which could decrease divertor stray light component by 10..100 times depending on incidence angle of light.},
doi = {10.1063/1.4894047},
journal = {AIP Conference Proceedings},
number = 1,
volume = 1612,
place = {United States},
year = {Thu Aug 21 00:00:00 EDT 2014},
month = {Thu Aug 21 00:00:00 EDT 2014}
}
  • ITER first mirrors (FMs), as the first components of most ITER optical diagnostics, will be exposed to high plasma radiation flux and neutron load. To reduce the FMs heating and optical surface deformation induced during ITER operation, the use of relevant materials and cooling system are foreseen. The calculations led on different materials and FMs designs and geometries (100 mm and 200 mm) show that the use of CuCrZr and TZM, and a complex integrated cooling system can limit efficiently the FMs heating and reduce their optical surface deformation under plasma radiation flux and neutron load. These investigations were usedmore » to evaluate, for the ITER equatorial port visible/infrared wide angle viewing system, the impact of the FMs properties change during operation on the instrument main optical performances. The results obtained are presented and discussed.« less
  • In preparation for ITER, JET has been upgraded with a new ITER-like wall (ILW), whereby the main plasma facing components, previously of carbon, have been replaced by mainly Be in the main chamber and W in the divertor. As part of the many diagnostic enhancements, a new, survey, visible spectroscopy diagnostic has been installed for the characterization of the ILW. An array of eight lines-of-sight (LOS) view radially one of the two JET neutral beam shine through areas (W coated carbon fibre composite tiles) at the inner wall. In addition, one vertical LOS views the solid W tile at themore » outer divertor. The light emitted from the plasma is coupled to a series of compact overview spectrometers, with overall wavelength range of 380-960 nm and to one high resolution Echelle overview spectrometer covering the wavelength range 365-720 nm. The new survey diagnostic has been absolutely calibrated in situ by means of a radiometric light source placed inside the JET vessel in front of the whole optical path and operated by remote handling. The diagnostic is operated in every JET discharge, routinely monitoring photon fluxes from intrinsic and extrinsic impurities (e.g., Be, C, W, N, and Ne), molecules (e.g., BeD, D{sub 2}, ND) and main chamber and divertor recycling (typically D{alpha}, D{beta}, and D{gamma}). The paper presents a technical description of the diagnostic and first measurements during JET discharges.« less
  • We have obtained deep, high spatial and spectral resolution, long-slit spectra of the H{alpha} nebulae in the cool cores of nine galaxy clusters. This sample provides a wealth of information on the ionization state, kinematics, and reddening of the warm gas in the cool cores of galaxy clusters. We find evidence for only small amounts of reddening in the extended, line-emitting filaments, with the majority of filaments having E(B - V) < 0.2. We find, in agreement with previous works, that the optical emission in cool core clusters has elevated low-ionization line ratios. The combination of [O III]/H{beta}, [N II]/H{alpha},more » [S II]/H{alpha}, and [O I]/H{alpha} allow us to rule out collisional ionization by cosmic rays, thermal conduction, and photoionization by intracluster medium (ICM) X-rays and active galactic nuclei as strong contributors to the ionization in the bulk of the optical line-emitting gas in both the nuclei and filaments. The data are adequately described by a composite model of slow shocks and star formation. This model is further supported by an observed correlation between the line widths and low-ionization line ratios which becomes stronger in systems with more modest star formation activity based on far-ultraviolet observations. We find that the more extended, narrow filaments tend to have shallower velocity gradients and narrower line widths than the compact filamentary complexes. We confirm that the widths of the emission lines decrease with radius, from FWHM {approx}600 km s{sup -1} in the nuclei to FWHM {approx}100 km s{sup -1} in the most extended filaments. The variation of line width with radius is vastly different than what is measured from stellar absorption lines in a typical giant elliptical galaxy, suggesting that the velocity width of the warm gas may in fact be linked to ICM turbulence and, thus, may provide a glimpse into the amount of turbulence in cool cores. In the central regions (r < 10 kpc) of several systems the warm gas shows kinematic signatures consistent with rotation, consistent with earlier work. We find that the kinematics of the most extended filaments in this sample are broadly consistent with both infall and outflow, and recommend further studies linking the warm gas kinematics to both radio and X-ray maps in order to further understand the observed kinematics.« less
  • An alternative residual ion removal concept for the ITER neutral beam system is presented. It consists of magnetic deflection of the residual ions to in-line ion dumps. The target plates are hit from one side and form a 0.5-m-wide opening to the beam. First calculations show that for the most severe case of a 3-mrad beam, the maximum power load can be kept below 15 MW/m{sup 2}, using a different horizontal focal length. However, this different beamlet optic increases the beam peak power density changing the plasma deposition profile and increasing the shine-through power during low-density operation. First calculations showedmore » that using a passive screening, the additional stray field created by the magnet could be kept below the required 1 gauss within the neutralizer. The overall beamline transmission increases by {approx}10% (i.e., an additional 1.7-MW injected power for each beamline for a 3-mrad beam) due to the open structure of the magnet and the ion dumps. Furthermore, the concept offers a larger operating window regarding beam alignment, divergence, steering, and transmission, and it avoids creating accelerated secondary electrons.« less
  • The present status of investigations on the first mirror (FM) problem is discussed on the basis of the last experimental results obtained in modern tokamaks and laboratory devices. Engineering solutions that are necessary for protection of Fms for CXRS and H-alpha diagnostics are considered. Future plans for R and D that has yet to be done are presented. Results of neutron irradiation and heating tests of multilayered dielectric mirrors are given briefly.