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Title: Design of polarizers for a mega-watt long-pulse millimeter-wave transmission line on the large helical device

The polarizer is one of the critical components in a high-power millimeter-wave transmission line. It requires full and highly efficient coverage of any polarization states, high-power tolerance, and low-loss feature. Polarizers with rounded shape at the edge of the periodic groove surface are designed and fabricated by the machining process for a mega-watt long-pulse millimeter-wave transmission line of the electron cyclotron resonance heating system in the large helical device. The groove shape of λ/8- and λ/4-type polarizers for an 82.7 GHz transmission line is optimally designed in an integral method developed in the vector theories of diffraction gratings so that the efficiency to realize any polarization state can be maximized. The dependence of the polarization states on the combination of the two polarizer rotation angles (Φ{sub λ/8}, Φ{sub λ/4}) is examined experimentally in a low-power test with the newly developed polarization monitor. The results show that the measured polarization characteristics are in good agreement with the calculated ones.
Authors:
; ; ; ; ; ; ; ; ; ; ;  [1] ; ; ;  [2]
  1. National Institute for Fusion Science, 322-6 Oroshi-cho, Toki 509-5292 (Japan)
  2. Department of Energy Engineering and Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8602 (Japan)
Publication Date:
OSTI Identifier:
22392360
Resource Type:
Journal Article
Resource Relation:
Journal Name: Review of Scientific Instruments; Journal Volume: 86; Journal Issue: 2; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY; DESIGN; DIFFRACTION GRATINGS; ECR HEATING; EFFICIENCY; GHZ RANGE 01-100; LHD DEVICE; PERIODICITY; POLARIZATION; POWER TRANSMISSION LINES; PULSES; SURFACES