[Table of Contents]

Plasma and Fusion Research

Volume 2, S1035 (2007)

Regular Articles

Instrumental Capabilities and Limitations of Two-Dimensional Phase Contrast Imaging on LHD
Leonid VYACHESLAVOV1), Kenji TANAKA, Clive MICHAEL, Andrei SANIN1), Kazuo KAWAHATA and Shigeki OKAJIMA2)
National Institute for Fusion Science, Toki 509-5952, Japan
1)
Budker Institute of Nuclear Physics, 630090, Novosibirsk, RUSSIA
2)
Chubu University Kasugai 487-8501, Japan
(Received 8 December 2006 / Accepted 2 April 2007 / Published 20 November 2007)

Abstract

A novel phase contrast imaging is employed for diagnostics of plasma density fluctuations on LHD. With the use of two dimensional 48 ch (6×8) detector array and CO2 laser probe beam this technique permits observation of radial profiles of density fluctuation during a single discharge either within the entire plasma diameter in overview mode or within some fraction of the diameter in zoom mode. The velocity of density fluctuations in laboratory frame can be determined simultaneously with fluctuations of velocities. Analysis of system performance was made with the use of numerical calculations. The targets for the analysis include wave number and spatial resolution of the method, contrast of instrumental function, which is determined by low k signal leakage into the high k spectral region, and focal depth of the optical system for different fluctuation wave numbers. The role of shortcomings of optical system like distortion of the optical front by diffraction is studied. Suggestions for future upgrade of the diagnostics are advanced.

Keywords

LHD, two-dimensional, phase contrast, microfluctuation

DOI: 10.1585/pfr.2.S1035

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References

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This paper may be cited as follows:

Leonid VYACHESLAVOV, Kenji TANAKA, Clive MICHAEL, Andrei SANIN, Kazuo KAWAHATA and Shigeki OKAJIMA, Plasma Fusion Res. 2, S1035 (2007).