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

0531029 - ÚFP 2021 RIV US eng J - Journal Article
Bogár, Ondrej - Zajac, Jaromír - Žáček, František - Varavin, Mykyta - Hron, Martin - Pánek, Radomír - Silva, A.
Microwave reflectometer for density profile and turbulence measurements on the COMPASS tokamak.
Review of Scientific Instruments. Roč. 91, č. 1 (2020), č. článku 013515. ISSN 0034-6748. E-ISSN 1089-7623
R&D Projects: GA MŠMT(CZ) LM2015045; GA ČR(CZ) GA19-15229S
Institutional support: RVO:61389021
Keywords : COMPASS * tokamak * turbulence measurement
OECD category: Fluids and plasma physics (including surface physics)
Impact factor: 1.523, year: 2020
Method of publishing: Limited access
https://aip.scitation.org/doi/10.1063/1.5099345

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.
Permanent Link: http://hdl.handle.net/11104/0309793