Abstract
In order to measure the internal structure of fluctuation, a broadband frequency-tunable system, which has a fast and stable hopping operation, has been developed in the large helical device. For constructing an accurate heterodyne phase detection system, a single-sideband (SSB) modulation technique is applied. Recently, high performance (SSB) modulators have been available in the wide band frequency range and its sideband rejection is around−20 dB. The frequency multiplier and mixer deformed the signal and the band-pass filter is used effectively to attain high signal-to-noise ratio.
Acknowledgements
This work was partially supported by a Grant-in-Aid for Scientific Research on Priority Areas (Nos. 18035015 and 20026010) and a Grant-in-Aid for Young Scientists (A) (No. 18686075) from the Ministry of Education, Culture, Sports, Science and Technology Japan and also a budgetary Grant-in-Aid No. NIFS08ULHH507 of the National Institute for Fusion Science.