Development of 2-D horn-antenna millimeter-wave imaging device (HMID) for the plasma diagnostics

Y Nagayama; N Ito; D Kuwahara; H Tsuchiya; S Yamaguchi

doi:10.1063/1.4980150

Development of 2-D horn-antenna millimeter-wave imaging device (HMID) for the plasma diagnostics

Rev Sci Instrum. 2017 Apr;88(4):044703. doi: 10.1063/1.4980150.

Authors

Y Nagayama¹, N Ito², D Kuwahara³, H Tsuchiya¹, S Yamaguchi⁴

Affiliations

¹ National Institute for Fusion Science, National Institute for Natural Sciences, Toki 509-5292, Japan.
² National Institute of Technology, Ube College, Ube 755-8555, Japan.
³ Tokyo University of Agriculture and Technology, Koganei 184-8588, Japan.
⁴ Kansai University, Suita 564-8680, Japan.

PMID: 28456234
DOI: 10.1063/1.4980150

Abstract

The two-dimensional (2-D) Horn-antenna Millimeter-wave Imaging Device (HMID) has been developed for the O-mode Microwave Imaging Reflectometry (O-MIR) in the Large Helical Device (LHD). The detectable frequency range of the HMID is 23-33 GHz, which corresponds to the cutoff electron density of 0.8-1.5 × 10¹⁹ m^-3 in the O-MIR. The HMID is a 2-D imaging device that improves on the horn-antenna mixer array, which had been developed for the X-mode MIR in the LHD. In the HMID, the signal (RF) wave from the horn antenna is transmitted to the microstrip line by the finline transmitter, and this is mixed by the double-balanced-mixer with the local oscillation wave that is fed by a coaxial cable. By using the HMID, the MIR optical system can be significantly simplified.