First operations with the new Collective Thomson Scattering diagnostic on the Frascati Tokamak Upgrade device

W. Bin, A. Bruschi, O. D'Arcangelo, C. Castaldo, M. De Angeli, L. Figini, C. Galperti, S. Garavaglia, G. Granucci, G. Grosso, Søren Bang Korsholm, M. Lontano, V. Mellera, D. Minelli, A. Moro, A. Nardone, Stefan Kragh Nielsen, Jesper Rasmussen, A. Simonetto, Morten Stejner PedersenU. Tartari

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Abstract

Anomalous emissions were found over the last few years in spectra of Collective Thomson Scattering (CTS) diagnostics in tokamak devices such as TEXTOR, ASDEX and FTU, in addition to real CTS signals. The signal frequency, down-shifted with respect to the probing one, suggested a possible origin in Parametric Decay Instability (PDI) processes correlated with the presence of magnetic islands and occurring for pumping wave power levels well below the threshold predicted by conventional models. A threshold below or close to the Electron Cyclotron Resonance Heating (ECRH) power levels could limit, under certain circumstances, the use of the ECRH in fusion devices. An accurate characterization of the conditions for the occurrence of this phenomenon and of its consequences is thus of primary importance. Exploiting the front-steering configuration available with the real-time launcher, the implementation of a new CTS setup now allows studying these anomalous emission phenomena in FTU under conditions of density and wave injection geometry that are more similar to those envisaged for CTS in ITER. The upgrades of the diagnostic are presented as well as a few preliminary spectra detected with the new system during the very first operations in 2014.
Original languageEnglish
Article numberP10007
JournalJournal of Instrumentation
Volume10
Issue number10
ISSN1748-0221
DOIs
Publication statusPublished - 2015
Event1st EPS Conference on Plasma Diagnostics - Frascati, Italy
Duration: 14 Apr 201517 Apr 2015
Conference number: 1

Conference

Conference1st EPS Conference on Plasma Diagnostics
Number1
CountryItaly
CityFrascati
Period14/04/201517/04/2015

Bibliographical note

The present work has been carried out under an EUROfusion Enabling Research project. A shorter version of this contribution is due to be published in PoS at: 1st EPS conference on Plasma Diagnostics.

Keywords

  • Nuclear instruments and methods for hot plasma diagnostics
  • Microwave Antennas

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