15-19 April 2018
Paradise Point Resort & Spa
America/Los_Angeles timezone

6.23 Development of high speed full digital processing phase detector for interferometry

17 Apr 2018, 10:30
2h 1m
Paradise Point Resort & Spa

Paradise Point Resort & Spa

1404 Vacation Rd, San Diego, CA 92109

Speakers

Takashi Minami (Institute of Advanced Energy, Kyoto University) Yasuhiko Ito (National Institute for Fusion Science) Yoshiaki Ohtani (National Institutes for Quantum and Radiological Science and Technology) Shinsuke Ohshima (Institute of Advanced Energy, Kyoto University) Kazunobu Nagasaki (Institute of Advanced Energy, Kyoto University) Hideya Nakanishi (National Institute for Fusion Science) Ryo Yasuhara (National Institute for Fusion Science) Hisayoshi Funaba (National Institute for Fusion Science) Ichihiro Yamada (National Institute for Fusion Science) Tsuyoshi Akiyama (National Institute for Fusion Science)

Description

A fully digital type phase detector for plasma interferometry is developing. It can operate even in the situation where the phase changes rapidly or where the input signal is too small to drive the correct phase change from the IF signal. It directly converts the IF signal waveform of the interferometer to the phase signal by a data processing in a logic circuit, thereby the phase is derived from the full waveform of the IF signal. The IF signal of the interferometer is converted to I/Q signals by Hilbert transform, processed with a digital low-pass filter, and polar coordinates are converted by a CORDIC algorithm to obtain the phase signal. A simulation of the high speed full digital processing phase detector shows that the fringe jump does not occur until a phase change rate of 0.85 × 10^6 rad/s. This value is sufficiently large as compared with the predicted phase velocity in density rise due to the pellet injection. The phase conversion has been simulated using the real IF signal of the interferometer measured with Heliotron J. The results show that the phase signal is successfully calculated by the full digital processing method from the IF signal in which the phase derivation is impossible by the conventional analog phase detector.

Primary author

Takashi Minami (Institute of Advanced Energy, Kyoto University)

Co-authors

Yasuhiko Ito (National Institute for Fusion Science) Yoshiaki Ohtani (National Institutes for Quantum and Radiological Science and Technology) Shinsuke Ohshima (Institute of Advanced Energy, Kyoto University) Kazunobu Nagasaki (Institute of Advanced Energy, Kyoto University) Hideya Nakanishi (National Institute for Fusion Science) Ryo Yasuhara (National Institute for Fusion Science) Hisayoshi Funaba (National Institute for Fusion Science) Ichihiro Yamada (National Institute for Fusion Science) Tsuyoshi Akiyama (National Institute for Fusion Science)

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