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Title: Plasma diagnostic system using optical fibers with high numerical aperture

Abstract

A diagnostic system using optical fibers with high numerical apertures is constructed for investigating a structure of magnetically confined plasma. Since the fiber has no convex lens at its front facet, the radiation from all plasmas included in the viewing angle of the fiber is utilized. First, theoretical forms are derived to determine the structure of the plasma from optical signals of a few fibers arranged axisymmetrically around the plasma. Second, the numerical aperture is measured by a simple method using a circular fluorescent lamp. Third, the theoretical forms are ascertained by a mock-up experiment where a light source representing a model plasma is constructed by a matrix array of straight fluorescent lamps. In this experiment, the effect of a reflected light from a wall of a vacuum vessel is investigated. Finally, the optical system is applied to a field-reversed-configuration plasma. Obtained structures of the plasma for n=1 and 2 toroidal modes are compared with the results of the conventional method using the fibers with convex lenses. The former results agree well with the latter ones in spite of the use of one-sixth the number of fibers in the latter method.

Authors:
; ; ; ; ; ; ; ;  [1]
  1. Institute of Science and Technology, Tokyo University of Agriculture and Technology, Koganei-shi 184-8588 (Japan)
Publication Date:
OSTI Identifier:
20853286
Resource Type:
Journal Article
Journal Name:
Review of Scientific Instruments
Additional Journal Information:
Journal Volume: 77; Journal Issue: 6; Other Information: DOI: 10.1063/1.2204908; (c) 2006 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0034-6748
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; APERTURES; CONTAINERS; FIELD-REVERSED THETA PINCH DEVICES; LENSES; LIGHT SOURCES; OPTICAL FIBERS; OPTICAL SYSTEMS; PLASMA; PLASMA DIAGNOSTICS; PLASMA SIMULATION; REVERSE-FIELD PINCH; REVERSED-FIELD PINCH DEVICES; WALL EFFECTS

Citation Formats

Ohkuma, Yasunori, Kanamaru, Yuki, Hasegawa, Yoshinori, Fujino, Toshiyuki, Fujimoto, Kayoko, Gota, Hiroshi, Asai, Tomohiko, Takahashi, Tsutomu, Nogi, Yasuyuki, and College of Science and Technology, Nihon University, Tokyo 101-8308. Plasma diagnostic system using optical fibers with high numerical aperture. United States: N. p., 2006. Web. doi:10.1063/1.2204908.
Ohkuma, Yasunori, Kanamaru, Yuki, Hasegawa, Yoshinori, Fujino, Toshiyuki, Fujimoto, Kayoko, Gota, Hiroshi, Asai, Tomohiko, Takahashi, Tsutomu, Nogi, Yasuyuki, & College of Science and Technology, Nihon University, Tokyo 101-8308. Plasma diagnostic system using optical fibers with high numerical aperture. United States. https://doi.org/10.1063/1.2204908
Ohkuma, Yasunori, Kanamaru, Yuki, Hasegawa, Yoshinori, Fujino, Toshiyuki, Fujimoto, Kayoko, Gota, Hiroshi, Asai, Tomohiko, Takahashi, Tsutomu, Nogi, Yasuyuki, and College of Science and Technology, Nihon University, Tokyo 101-8308. 2006. "Plasma diagnostic system using optical fibers with high numerical aperture". United States. https://doi.org/10.1063/1.2204908.
@article{osti_20853286,
title = {Plasma diagnostic system using optical fibers with high numerical aperture},
author = {Ohkuma, Yasunori and Kanamaru, Yuki and Hasegawa, Yoshinori and Fujino, Toshiyuki and Fujimoto, Kayoko and Gota, Hiroshi and Asai, Tomohiko and Takahashi, Tsutomu and Nogi, Yasuyuki and College of Science and Technology, Nihon University, Tokyo 101-8308},
abstractNote = {A diagnostic system using optical fibers with high numerical apertures is constructed for investigating a structure of magnetically confined plasma. Since the fiber has no convex lens at its front facet, the radiation from all plasmas included in the viewing angle of the fiber is utilized. First, theoretical forms are derived to determine the structure of the plasma from optical signals of a few fibers arranged axisymmetrically around the plasma. Second, the numerical aperture is measured by a simple method using a circular fluorescent lamp. Third, the theoretical forms are ascertained by a mock-up experiment where a light source representing a model plasma is constructed by a matrix array of straight fluorescent lamps. In this experiment, the effect of a reflected light from a wall of a vacuum vessel is investigated. Finally, the optical system is applied to a field-reversed-configuration plasma. Obtained structures of the plasma for n=1 and 2 toroidal modes are compared with the results of the conventional method using the fibers with convex lenses. The former results agree well with the latter ones in spite of the use of one-sixth the number of fibers in the latter method.},
doi = {10.1063/1.2204908},
url = {https://www.osti.gov/biblio/20853286}, journal = {Review of Scientific Instruments},
issn = {0034-6748},
number = 6,
volume = 77,
place = {United States},
year = {Thu Jun 15 00:00:00 EDT 2006},
month = {Thu Jun 15 00:00:00 EDT 2006}
}