Contributo in atti di convegno, 2019, ENG, 10.1051/epjconf/201920302005

Side emissions during EC injection for PDI studies in FTU tokamak

Bruschi A.; Alessi A.; Baiocchi B.; Bin W.; D'Arcangelo O.; Fanale F.; Figini L.; Galperti C.; Garavaglia S.; Gittini G.; Granucci G.; Grosso G.; Lubyako L.; Mazzotta C.; Mellera V.; Moro A.; Orsitto F.; Pallotta F.; Rocchi G.; Simonetto A.; Tartari U.; Tudisco O.

CNR ISTP, Istituto per la Scienza e Tecnologia dei Plasmi, Milano, Italy; Ex Istituto di Fisica del Plasma, Consiglio Nazionale delle Ricerche, Milano Italy; ENEA Fusion and Nuclear Safety Department, C.R.Frascati, (Roma) Italy; Swiss Plasma Center, Ecole Polytéchnique Fédérale de Lausanne, Switzerland; Institute of Applied Physics, Novgorod, Russia; Consorzio CREATE, Università degli Studi di Napoli, Italy.

The evidence of Parametric Decay Instabilities (PDI) excited by the ECH power injected in O-Mode has been explored in FTU Tokamak, using the Collective Thomson Scattering (CTS) diagnostic. The experiments show evidences to support the hypothesis of low-threshold excitation of waves generated by PDI mechanisms, formerly proposed in the case of 2nd harmonic X-mode injection in TEXTOR and ASDEX-U. Theoretical analysis predicts low-threshold parametric decay also for O-mode pump-wave injection, which can be injected in FTU at frequencies close to the first Harmonic EC resonance. Experiments were made at different magnetic fields, injecting the 140 GHz probe and observing the emission from the second antenna of the EC launcher in poloidally symmetric and asymmetric configurations, in presence of MHD islands. The signal is detected by the CTS radiometers, with a fast digitizer allowing the spectral reconstruction at very fine time and frequency scales. Different types of emissions are studied in detail, comparing them with the magnetic island rotation frequency in different plasma conditions. In order to locate the plasma volume originating the emissions, a new antenna and receiving line has been installed.

20th Joint Workshop on Electron Cyclotron Emission and Electron Cyclotron Resonance Heating (EC20), pp. 02005-1–02005-6, Greifswald, Germany, 14-17 May 2018

Keywords

Side emissions, EC injection, PDI, FTU, tokamak

CNR authors

Fanale Francesco, Baiocchi Benedetta, Grosso Giovanni Maria, Tartari Umberto, Gittini Giuseppe, Granucci Gustavo, Garavaglia Saul Francesco, Bin William Maurizio, Figini Lorenzo, Moro Alessandro Andrea, Mellera Vittoria Antonia, Pallotta Fabrizio, Alessi Edoardo, Simonetto Alessandro, Bruschi Alessandro

CNR institutes

IFP – Istituto di fisica del plasma "Piero Caldirola", ISTP – Istituto per la Scienza e Tecnologia dei Plasmi