[Table of Contents]

Plasma and Fusion Research

Volume 3, 018 (2008)

Regular Articles

Development of a Plasma Diagnostics System Using an Impulse Waveform Voltage
Tokihiko TOKUZAWA, Kazuo KAWAHATA, Yasuhiko ITO, Kenji TANAKA, Ichihiro YAMADA and LHD Experimental Group
National Institute for Fusion Science, Toki 509-5292, Japan
(Received 30 November 2007 / Accepted 7 March 2008 / Published 28 April 2008)

Abstract

A new application using an electric impulse signal has been developed for electron density profile measurements in the Large Helical Device (LHD). Using an impulse waveform voltage, which has broadband frequency components, we constructed an ultrashort pulsed radar reflectometer with 28 channels in X-, Ka-, and U-band frequency components. The effect of the bandwidth of an inline band-pass filter was investigated, and was optimized. For a multiple-channel and multiple-frequency band system, a new switching technique and multiplexer were developed. Using the Abel inversion method, the reconstructed electron density profile was obtained from the delay time as a function of the probing frequency. Good agreement with other diagnostics was obtained.

Keywords

impulse, microwave radar, electron density profile, microwave reflectometer, LHD

DOI: 10.1585/pfr.3.018

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This paper may be cited as follows:

Tokihiko TOKUZAWA, Kazuo KAWAHATA, Yasuhiko ITO, Kenji TANAKA, Ichihiro YAMADA and LHD Experimental Group, Plasma Fusion Res. 3, 018 (2008).