[Table of Contents]

Plasma and Fusion Research

Volume 9, 3405024 (2014)

Regular Articles

Development of a Real-Time Power/Polarization Monitor using FPGA for Electron Cyclotron Resonance Heating on LHD
Ryohei MAKINO1), Shin KUBO1,2), Kenya KOBAYAHI1), Sakuji KOBAYASHI2), Takashi SHIMOZUMA2), Yasuo YOSHIMURA2), Hiroe IGAMI2), Hiromi TAKAHASHI2), Shinya OGASAWARA1) and Takashi MUTOH2)
Department of Energy Engineering and Science, Nagoya University, Nagoya 464-8603, Japan
National Institute for Fusion Science, 322-6 Oroshi-cho, Toki 509-5292, Japan
(Received 10 December 2013 / Accepted 5 February 2014 / Published 14 March 2014)


For optimization of electron cyclotron resonance heating (ECRH), it is important to measure power and polarization states of injected millimeter-waves in real-time. Arbitrary polarization states of millimeter-waves are realized by two grating mirror polarizers set at miter-bends in the corrugated waveguide transmission system on the Large Helical Device (LHD). The polarization state of an injected millimeter-wave determines the mode excitation purity, and therefore the power absorption efficiency in plasmas. The real-time power/polarization monitor of the injected millimeter-wave is required for optimization and/or feedback control of ECRH. The real-time power/polarization monitor is under development to be installed on a miter-bend near the ECRH antenna on LHD. Amplitudes and phases of two orthogonal polarizations of injected millimeter-waves are measured to determine the power and polarization states of waves. In this paper, the design and performance test of the real-time power/polarization monitor are reported. Intensities and relative phase of two orthogonal polarizations are measured by a newly developed monitor with heterodyne interferometer and fast ADC (800 MHz) with FPGA. Hardware of the power/polarization monitor works as designed qualitatively.


power/polarization monitor, millimeter-waves, electron cyclotron resonance heating, LHD, miter-bend, FPGA

DOI: 10.1585/pfr.9.3405024


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This paper may be cited as follows:

Ryohei MAKINO, Shin KUBO, Kenya KOBAYAHI, Sakuji KOBAYASHI, Takashi SHIMOZUMA, Yasuo YOSHIMURA, Hiroe IGAMI, Hiromi TAKAHASHI, Shinya OGASAWARA and Takashi MUTOH, Plasma Fusion Res. 9, 3405024 (2014).