Modification of the collective Thomson scattering radiometer in the search for parametric decay on TEXTOR

Stefan Kragh Nielsen, Mirko Salewski, W. Bongers, Søren Bang Korsholm, Frank Leipold, Fernando Meo, Poul Michelsen, D Moseev, J W Oosterbeek, Morten Stejner Pedersen, E. Westerhof

Research output: Contribution to journalJournal articleResearchpeer-review


Strong scattering of high-power millimeter waves at 140 GHz has been shown to take place in heating and current-drive experiments at TEXTOR when a tearing mode is present in the plasma. The scattering signal is at present supposed to be generated by the parametric decay instability. Here we describe the heterodyne detection system used to characterize the newly discovered signal measured at TEXTOR, and we present spectral shapes in which the signal can appear under different conditions. The radiation is collected by the receiver through a quasi-optical transmission line that is independent of the electron cyclotron resonance heating transmission line, and so the scattering geometry is variable. The signal is detected with 42 frequency channels ranging from 136 to 142 GHz. We demonstrate that the large signal does not originate from gyrotron spurious radiation. The measured signal agrees well with independent backscattering radiometer data.
Original languageEnglish
JournalReview of Scientific Instruments
Issue number11
Pages (from-to)113508
Number of pages5
Publication statusPublished - 2012


  • Eelectromagnetic wave scattering
  • Millimetre waves
  • Plasma diagnostics
  • Radiometers

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