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Electron Density Reconstruction and Optimum Beam Arrangement of Far-Infrared Interferometer in Heliotron J

Nan SHI, Shinsuke OHSHIMA, Kenji TANAKA¹⁾, Takashi MINAMI, Kazunobu NAGASAKI, Satoshi YAMAMOTO, Yoshiaki OHTANI²⁾, Linge ZANG²⁾, Tohru MIZUUCHI, Hiroyuki OKADA, Shinichiro KADO, Shinji KOBAYASHI, Shigeru KONOSHIMA, Naoki KENMOCHI²⁾ and Fumimichi SANO

Institute of Advanced Energy, Kyoto University, Kyoto 611-0011, Japan

1)

National Institute for Fusion Science, Toki 509-5292, Japan

2)

Graduate School of Energy Science, Kyoto University, Kyoto 611-0011, Japan

(Received 20 November 2013 / Accepted 18 February 2014 / Published 7 May 2014)

Abstract

A multichannel far-infrared (FIR) laser interferometer is being developed for the helical-axis heliotron device Heliotron J with asymmetrical poloidal cross-section to study high-density plasma. Due to the shape of the cross-section, a new density reconstruction method based on the regularization technique was investigated for obtaining the electron density profile from the line-integrated density. For this purpose, the regularization parameter was optimized and determined by the generalized cross-validation (GCV) function and singular value decomposition (SVD). The reconstruction results show that the reconstructed profiles can be improved by carefully considering the beam position arrangement. The optimum beam arrangement is discussed in detail.

Copyright (c) 2014 The Japan Society of Plasma Science and Nuclear Fusion Research

Keywords

electron density reconstruction, regularization, GCV, SVD, FIR interferometer, Heliotron J

DOI: 10.1585/pfr.9.3402043

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References

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This paper may be cited as follows:

Nan SHI, Shinsuke OHSHIMA, Kenji TANAKA, Takashi MINAMI, Kazunobu NAGASAKI, Satoshi YAMAMOTO, Yoshiaki OHTANI, Linge ZANG, Tohru MIZUUCHI, Hiroyuki OKADA, Shinichiro KADO, Shinji KOBAYASHI, Shigeru KONOSHIMA, Naoki KENMOCHI and Fumimichi SANO, Plasma Fusion Res. 9, 3402043 (2014).