Plasma and Fusion Research
Online ISSN : 1880-6821
ISSN-L : 1880-6821
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Notch Filter in 70 GHz Range for Microwave Plasma Diagnostics
Masaki NISHIURAShin KUBOKenji TANAKASakuji KOBAYASHIKohta OKADATeruki NISHIMURAKoji OKADAHiroshi KASAHARAShinya OGASAWARATakashi SHIMOZUMATakashi MUTOHKazuo KAWAHATATeruo SAITOYoshinori TATEMATSULHD experiment group
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2013 Volume 8 Pages 2402027

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Abstract

A notch filter for the rejection of stray light from gigahertz range heating sources was developed to protect a vulnerable microwave plasma diagnostic system. As one of the applications, we consider the installation of the notch filter into the receiver of a collective Thomson scattering diagnostic in the Large Helical Device. Experimental observations indicate that two types of notch filters are required for main and spurious mode rejection; they have very narrow, steep shapes to avoid disturbing the diagnostic signal. On the basis of numerically simulated results, notch filters were fabricated, and their performance was evaluated. An attenuation level of 35 dB at 74.746 GHz with a 3 dB bandwidth of 0.49 GHz is achieved by two pairs of resonator cavities. This attenuation is acceptable in our study.

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© 2013 by The Japan Society of Plasma Science and Nuclear Fusion Research
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