[Table of Contents]

Plasma and Fusion Research

Volume 4, 042 (2009)

Regular Articles


Divertor Impurity-Influx Monitor for ITER: Spectral Throughput Measurement on an Optical Prototype for the Upper Port and Optimization of Viewing Chords based on Computerized Tomography
Atsushi IWAMAE, Tatsuo SUGIE, Hiroaki OGAWA and Yoshinori KUSAMA
Fusion Research and Development Directorate, Japan Atomic Energy Agency, Naka, Ibaraki 311-0193, Japan
(Received 16 June 2009 / Accepted 14 July 2009 / Published 4 September 2009)

Abstract

We are developing a spectroscopic diagnostics system in ultraviolet and visible wavelength regions for monitoring ITER divertor plasmas. An equivalent-size prototype of the optical components for viewing upper port fanarray chords has been assembled as a system to measure spectral throughput, i.e., étendu. Collisional-radiative models for HeI and CIV are used to estimate the emission line intensities of helium ash and carbon impurity ions in a divertor region of a burning plasma. The estimated line intensity of CIV, λ772.6 nm, satisfies ITER requirements for the time resolution of measurement of Ti. A numerical simulation of the computerized tomographic technique for various pairs of viewing fan arrays has been applied to the divertor plasma region to reconstruct a two-dimensional distribution. The optimized pair of viewing fan arrays resolves a model distribution with a reasonable spatial resolution. We measure the reflectance of surfaces of carbon-fiber-composite and tungsten blocks, which make up the plasma-facing divertor target plates and the divertor dome. The reflectance of the surface of the tungsten divertor block is 23% at Hα (λ656.3 nm). A sandblast-processed tungsten surface effectively reduces direct reflectance; the resultant reflectance is less than 0.7%.


Keywords

divertor impurity-influx monitor, ITER, collisional-radiative model, computerized tomography, maximum entropy method, reflectance, tungsten, carbon-fiber-composite CFC

DOI: 10.1585/pfr.4.042


References

  • [1] A.J.H. Donné et al., Nucl. Fusion 47, S337 (2007).
  • [2] H. Ogawa et al., will appear in Nucl. Fusion. Proceedings of IAEA conference IT-p6-23 (2009).
  • [3] T. Sugie et al., Burning Plasma Diagnostics ed. G. Gorini et al. (AIP, 2008) p.218.
  • [4] H. Ogawa et al., Plasma Fusion Res. 2, S1054 (2007).
  • [5] H. Ogawa et al., Degin of Impurity Influx Monitor (Divertor) for ITER JAEA-Tech. 2006-015 (2006). http://jolissrch-inter.tokai-sc.jaea.go.jp/pdfdata/JAEA-Technology-2006-015.pdf
  • [6] T. Sugie et al., J. Plasma Fusion Res. 79, 1051 (2003).
  • [7] T. Sugie et al., Design of Divertor Impurity Monitoring System for ITER (II) JAERI-Tech 98-047 (1998). http://jolissrch-inter.tokai-sc.jaea.go.jp/pdfdata/JAERI-Tech-98-047.pdf
  • [8] T. Sugie et al., Design of Divertor Impurity Monitoring System for ITER JAERI-Tech 96-055 (1996).
  • [9] K.H. Behringer, J. Nucl. Mater. 145-147, 145 (1987).
  • [10] N.J. Peacock, Astrophys. Space Sci. 237, 341 (1996).
  • [11] H.P. Summers et al., Plasma Phys. Control. Fusion 34, 325 (1992).
  • [12] T. Nakano et al., J. Plasma Fusion Res. 80, 500 (2004).
  • [13] I. Beigman et al., Plasma Phys. Control. Fusion 49, 1833 (2007).
  • [14] B. Lipschultz et al., Nucl. Fusion 24, 977 (1984).
  • [15] C.H. Skinner et al., Nucl. Fusion 35, 143 (1995).
  • [16] C.H. Skinner et al., J. Nucl. Mater. 241-243, 887 (1997).
  • [17] T. Shikama et al., Phys. Plasmas 11, 47011 (2004).
  • [18] A. Iwamae et al., Phys. Plasmas 12, 042501 (2005).
  • [19] A. Iwamae et al., Phys. Plasmas 14, 042504 (2007).
  • [20] A. Iwamae et al., Plasma Phys. Control. Fusion 47, L41 (2005).
  • [21] T. Fujimoto and A. Iwamae Eds., Plasma Polarization Spectroscopy (Springer, Berlin Heidelberg, 2008).
  • [22] H. Iida et al., Nuclear Analysis Report G 73 DDD 2 W 0.2 (2004).
  • [23] T. Nishitani et al., Fusion Eng. Des. 42, 443 (1998).
  • [24] T. Sugie et al., J. Nucl. Mater. 329-333, 1481 (2004).
  • [25] R. Schneider et al., J. Nucl. Mater. 266-269, 175 (1999).
  • [26] V. Kotov, D. Reiter and A. S. Kukushkin, Numerical study of the ITER divertor plasma with the B2-EIRENE code package (Jülich 2007). http://www.eirene.de/kotov_solps42_report.pdf and private communication.
  • [27] M. Goto and T. Fujimoto, Collisional-radiative Model for Neutral Helium in Plasma: Excitation Cross Section and Singlet-triplet Wavefunctsion Mixing NIFS-DATA-043 (1997). http://www.nifs.ac.jp/report/NIFS-DATA-043.pdf
  • [28] M. Goto, JQSRT 76, 331 (2003).
  • [29] T. Fujimoto, Plasma Spectroscopy (Oxford University Press, Oxford, 2004).
  • [30] N. Iwama and S. Ohdachi, J. Plasma Fusion Res. 82, 399 (2006). [in Japanese]
  • [31] K. Fujimoto et al., Fusion Sci. Technol. 51, 2T, 247 (2007).
  • [32] K. Fujimoto et al., Plasma Fusion Res. 2, S1121 (2007).
  • [33] K. Fujimoto et al., Plasma Fusion Res. 4, 025 (2009).

This paper may be cited as follows:

Atsushi IWAMAE, Tatsuo SUGIE, Hiroaki OGAWA and Yoshinori KUSAMA, Plasma Fusion Res. 4, 042 (2009).