Microwave reflectometer for density profile and turbulence measurements on the COMPASS tokamak

The fast microwave reflectometer system on the COMPASS tokamak consists of an O-mode polarized K-band (18 GHz–26 GHz), Ka-band (26 GHz–40 GHz), and a part of U-band (40 GHz–54 GHz). The plasma density profile from the edge plasma area is measured using a fast sweeping rate up of to 6 µs of the probi...

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Bibliographic Details
Published in:Review of scientific instruments 2020-01, Vol.91 (1), p.013515-013515
Main Authors: Bogar, O., Zajac, J., Zacek, F., Varavin, M., Hron, M., Panek, R., Silva, A.
Format: Article
Language:English
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Summary:The fast microwave reflectometer system on the COMPASS tokamak consists of an O-mode polarized K-band (18 GHz–26 GHz), Ka-band (26 GHz–40 GHz), and a part of U-band (40 GHz–54 GHz). The plasma density profile from the edge plasma area is measured using a fast sweeping rate up of to 6 µs of the probing wave. The processing of the reflected signal is realized by the heterodyne detection configuration based on the I/Q modulator. Two different methods of dynamic calibration of the required linear sweep frequency, together with static frequency and dispersion calibration, were used. The electron density profile was reconstructed by a spectrogram-based method with four sweeps on average. The system has the capability to measure the mid-plane low-field side electron density profile in the density range from 4 × 1018 m−3 to 3.6 × 1019 m−3. Experimental results obtained on COMPASS discharges are presented to demonstrate the performance of the diagnostics.
ISSN:0034-6748
1089-7623
DOI:10.1063/1.5099345