Upgrade of the COMPASS tokamak microwave reflectometry system with I/Q modulation and detection.

0483663 - ÚFP 2018 RIV CH eng J - Journal Article
Zajac, Jaromír - Bogár, Ondrej - Varavin, Mykyta - Žáček, František - Hron, Martin - Pánek, Radomír - Nanobashvili, S. - Silva, A.
Upgrade of the COMPASS tokamak microwave reflectometry system with I/Q modulation and detection.
Fusion Engineering and Design. Roč. 123, November (2017), s. 911-914. ISSN 0920-3796. E-ISSN 1873-7196.
[SOFT 2016: Symposium on Fusion Technology /29./. Prague, 05.09.2016-09.09.2016]
R&D Projects: GA ČR(CZ) GA14-35260S
Institutional support: RVO:61389021
Keywords : Microwave reflectometry * Heterodyne detection * I/Q modulator * COMPASS tokamak
OECD category: Nuclear related engineering
Impact factor: 1.437, year: 2017
http://www.sciencedirect.com/science/article/pii/S0920379617303101

The microwave reflectometry system on COMPASS tokamak uses the frequency modulated continuous wave (FM-CW) in the K and Ka bands. The fast swept synthesizer together with the homodyne detection provides the complex beat frequency spectrum for the density profile reconstruction. The homodyne detection limits the use of reflectometry in the other applications like correlation or Doppler reflectometry. Our effort was to implement a heterodyne detection based on the existing system. We have decided to use a single-sideband modulator (SSBM) scheme to keep the compatibility with the fast sweeping. Lack of suitable SSBMs on the market leads us to use I/Q modulator, which is modulated by the in-quadrature signals.
Permanent Link: http://hdl.handle.net/11104/0278880