W-band millimeter-wave back-scattering system for high wavenumber turbulence measurements in LHD

T. Tokuzawa, K. Tanaka, T. Tsujimura, S. Kubo, M. Emoto, S. Inagaki, K. Ida, M. Yoshinuma, K. Y. Watanabe, H. Tsuchiya, A. Ejiri, T. Saito, K. Yamamoto

Research output: Contribution to journalArticlepeer-review

Abstract

A 90 GHz W-band millimeter-wave back-scattering system is designed and installed for measuring electron scale turbulence (k⊥ρs ∼40). A metal lens relay antenna is used for in-vessel beam focusing, and a beam diameter of less than 40 mm is achieved in the plasma core region. This antenna can be steered at an angle of 159° ± 6°, which almost covers the plasma radius. The estimated size of the scattering volume is ∼105 mm at the edge and 135 mm at the core, respectively. A 60 m corrugated waveguide is used to achieve a low transmission loss of ∼8 dB. A heterodyne detection system for millimeter-wave circuits with probing power modulation can distinguish the scattered signal from background noise.

Original languageEnglish
Article number043536
JournalReview of Scientific Instruments
Volume92
Issue number4
DOIs
Publication statusPublished - Apr 1 2021

All Science Journal Classification (ASJC) codes

  • Instrumentation

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