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Title: Progress in development of the neutron profile monitor for the large helical device

Abstract

The neutron profile monitor stably operated at a high-count-rate for deuterium operations in the Large Helical Device has been developed to enhance the research on the fast-ion confinement. It is composed of a multichannel collimator, scintillation-detectors, and a field programmable gate array circuit. The entire neutron detector system was tested using an accelerator-based neutron generator. This system stably acquires the pulse data without any data loss at high-count-rate conditions up to 8 × 10{sup 5} counts per second.

Authors:
;  [1]; ;  [1];  [2]; ;  [3];  [4]; ;  [5]
  1. National Institute for Fusion Science, Toki 509-5292 (Japan)
  2. (SOKENDAI), Toki 509-5292 (Japan)
  3. National Institute of Technology, Toyama College, 13 Hongo-machi, Toyama 939-8630 (Japan)
  4. Fusion Research and Development Directorate, Japan Atomic Energy Agency, Tokai, Naka, Ibaraki 319-1195 (Japan)
  5. Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan)
Publication Date:
OSTI Identifier:
22308635
Resource Type:
Journal Article
Resource Relation:
Journal Name: Review of Scientific Instruments; Journal Volume: 85; Journal Issue: 11; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY; 70 PLASMA PHYSICS AND FUSION TECHNOLOGY; COLLIMATORS; CONFINEMENT; COUNTING RATES; DEUTERIUM; IONS; LHD DEVICE; NEUTRON DETECTORS; NEUTRON GENERATORS; SCINTILLATION COUNTERS

Citation Formats

Ogawa, K., E-mail: ogawa.kunihiro@lhd.nifs.ac.jp, Kobuchi, T., Isobe, M., Takeiri, Y., The Graduate University for Advanced Studies, Takada, E., Uchida, Y., Ochiai, K., Tomita, H., and Uritani, A.. Progress in development of the neutron profile monitor for the large helical device. United States: N. p., 2014. Web. doi:10.1063/1.4890399.
Ogawa, K., E-mail: ogawa.kunihiro@lhd.nifs.ac.jp, Kobuchi, T., Isobe, M., Takeiri, Y., The Graduate University for Advanced Studies, Takada, E., Uchida, Y., Ochiai, K., Tomita, H., & Uritani, A.. Progress in development of the neutron profile monitor for the large helical device. United States. doi:10.1063/1.4890399.
Ogawa, K., E-mail: ogawa.kunihiro@lhd.nifs.ac.jp, Kobuchi, T., Isobe, M., Takeiri, Y., The Graduate University for Advanced Studies, Takada, E., Uchida, Y., Ochiai, K., Tomita, H., and Uritani, A.. 2014. "Progress in development of the neutron profile monitor for the large helical device". United States. doi:10.1063/1.4890399.
@article{osti_22308635,
title = {Progress in development of the neutron profile monitor for the large helical device},
author = {Ogawa, K., E-mail: ogawa.kunihiro@lhd.nifs.ac.jp and Kobuchi, T. and Isobe, M. and Takeiri, Y. and The Graduate University for Advanced Studies and Takada, E. and Uchida, Y. and Ochiai, K. and Tomita, H. and Uritani, A.},
abstractNote = {The neutron profile monitor stably operated at a high-count-rate for deuterium operations in the Large Helical Device has been developed to enhance the research on the fast-ion confinement. It is composed of a multichannel collimator, scintillation-detectors, and a field programmable gate array circuit. The entire neutron detector system was tested using an accelerator-based neutron generator. This system stably acquires the pulse data without any data loss at high-count-rate conditions up to 8 × 10{sup 5} counts per second.},
doi = {10.1063/1.4890399},
journal = {Review of Scientific Instruments},
number = 11,
volume = 85,
place = {United States},
year = 2014,
month =
}
  • Neutron monitoring is important to manage safety of fusion experiment facilities because neutrons are generated in fusion reactions. Monte Carlo simulations play an important role in evaluating the influence of neutron scattering from various structures and correcting differences between deuterium plasma experiments and in situ calibration experiments. We evaluated these influences based on differences between the both experiments at Large Helical Device using Monte Carlo simulation code MCNP5. A difference between the both experiments in absolute detection efficiency of the fission chamber between O-ports is estimated to be the biggest of all monitors. We additionally evaluated correction coefficients for somemore » neutron monitors.« less
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  • Z{sub eff} measurement system using a visible spectrometer has been newly designed and constructed instead of an old interference filter system to eliminate line emissions from the signal and to measure the Z{sub eff} value in low-density plasmas. The system consists of the Czerny-Turner-type spectrometer with a charge-coupled device camera and 44 optical fibers vertical array. The spectrometer is equipped with an additional toroidal mirror for further reduction in the astigmatism in addition to a flat and two spherical mirrors and three gratings (110, 120, and 1200 grooves/mm) with 30 cm focal length. The images from 44 optical fibers canmore » be detected without astigmatism in a wavelength range of 200-900 nm. Combination of the optical fiber (core diameter: 100 {mu}m) with the lens (focal length: 30 mm) provides spatial resolution of 30 mm at the plasma center. Results clearly indicate a very good focus image of the fiber and suggest the absence of the cross-talk between adjacent fiber images. Absolute intensity calibration has been done using a standard tungsten lamp to analyze the Z{sub eff} value. The bremsstrahlung profile and resultant Z{sub eff} profile have been obtained after Abel inversion of the signals observed in large helical device plasmas with elliptical poloidal cross section.« less