Articolo in rivista, 2019, ENG, 10.1088/1741-4326/aafe2a

Analysis of runaway electron expulsion during tokamak instabilities detected by a single-channel Cherenkov probe in FTU

Causa, F.; Buratti, P.; Alessi, E.; Angelini, B.; Apicella, M. L.; Apruzzese, G.; Artaserse, G.; Baiocchi, B.; Belli, F.; Bin, W.; Bombarda, F.; Boncagni, L.; Botrugno, A.; Briguglio, S.; Bruschi, A.; Buratti, P.; Calabro, G.; Cappelli, M.; Cardinali, A.; Carnevale, D.; Carraro, L.; Castaldo, C.; Causa, F.; Ceccuzzi, S.; Centioli, C.; Cesario, R.; Cianfarani, C.; Claps, G.; Cocilovo, V.; Cordella, F.; Crisanti, F.; D'Arcangelo, O.; De Angeli, M.; Di Troia, C.; Esposito, B.; Fanale, F.; Farina, D.; Figini, L.; Fogaccia, G.; Frigione, D.; Fusco, V.; Gabellieri, L.; Garavaglia, S.; Giovannozzi, E.; Gittini, G.; Granucci, G.; Grosso, G.; Iafrati, M.; Iannone, F.; Laguardia, L.; Lazzaro, E.; Lontano, M.; Maddaluno, G.; Magagnino, S.; Marinucci, M.; Marocco, D.; Mazzitelli, G.; Mazzotta, C.; Mellera, V.; Milovanov, A.; Minelli, D.; Mirizzi, F. C.; Moro, A.; Nowak, S.; Pacella, D.; Pallotta, F.; Panaccione, L.; Panella, M.; Pericoli-Ridolfini, V.; Pizzuto, A.; Podda, S.; Pucella, G.; Puiatti, M. E.; Ramogida, G.; Ravera, G.; Ricci, D.; Romano, A.; Simonetto, A.; Sozzi, C.; Tartari, U.; Tuccillo, A. A.; Tudisco, O.; Valisa, M.; Viola, B.; Vitale, E.; Vlad, G.; Zeniol, B.; Zerbini, M.; Zonca, F.; Aquilini, M.; Cefali, P.; Di Ferdinando, E.; Di Giovenale, S.; Giacomi, G.; Grosso, A.; Mezzacappa, M.; Pensa, A.; Petrolini, P.; Piergotti, V.; Raspante, B.; Rocchi, G.; Sibio, A.; Tilia, B.; Tulli, R.; Vellucci, M.; Zannetti, D.; Almaviva, S.; Bagnato, F.; Brolatti, G.; Buscarino, A.; Calacci, L.; Caneve, L.; Carlini, M.; Colao, F.; Corradino, C.; Costa, P.; Crescenzi, F.; Cucchiaro, A.; Ferro, G.; Gabrielli, A.; Galeani, S.; Galperti, C.; Gasior, P.; Gospodarczyk, M.; Jakubowski, L.; Kubkowska, M.; Lampasi, A.; Lazic, V.; Lubyako, L.; Maffia, G.; Martinelli, F.; Martin-Solis, J. R.; Maviglia, F.; Mazzuca, R.; Moneti, M.; Orsitto, F. P.; Palucci, A.; Passeri, M.; Popovic, Z.; Possieri, C.; Rabinski, M.; Ratynskaia, S.; Reale, M.; Roccella, S.; Sassano, M.; Starace, F.; Tolias, P.; Vertkov, A.; Zebrowski, J.; Zito, P.

CNR ISTP, Istituto per la Scienza e Tecnologia dei Plasmi, Milano, Italy; CNR, Ex Ist Fis Plasma Piero Caldirola, Milan, Italy; ENEA, Fus & Nucl Safety Dept, CR Frascati, Rome, Italy; Univ Roma Tor Vergata, Dipartimento Ingn Civile & Informat, Rome, Italy; Consorzio RFX (CNR, ENEA, INFN, Università di Padova, Acciaierie Venete SpA), Padova, Italy; CNR ISTP - Istituto per la Scienza e Tecnologia dei Plasmi, Sede di Padova, Italy; Univ Napoli Federico II, Consorzio CREATE, Naples, Italy; Ecole Polytech Fed Lausanne, Swiss Plasma Ctr, Lausanne, Switzerland; Univ Catania, Dept Elect Engn & Comp Engn, Catania, Italy; Univ Tuscia, Ctr Res & Disseminat Renewable Energy, Orte, Italy; Inst Plasma Phys & Laser Microfus, Warsaw, Poland; Natl Ctr Nucl Res, Otwock, Poland; Inst Appl Phys, Nizhnii Novgorod, Russia; Univ Carlos III Madrid, Madrid, Spain; KTH Royal Inst Technol, Space & Plasma Phys, Stockholm, Sweden; JSC Red Star, Moscow, Russia; FTU Team.

The expulsion of runaway electrons (REs) during different types of tokamak instabilities is analysed by means of a Cherenkov probe inserted into the scrape-off layer of the FTU tokamak. One such type of instability, the well-known tearing mode, is involved in disruptive plasma termination events, during which the risk of RE avalanche multiplication is highest. The second type, known as anomalous Doppler instability, influences RE dynamics by enhancing pitch angle scattering. Three scenarios are analysed here, characterised by different RE generation rates and mechanisms. The main conclusions are drawn from correlations between the Cherenkov probe and other diagnostics. In particular, the Cherenkov probe permits the detection of fast electron expulsion with a high level of detail, presenting peaks with 100% signal contrast during tearing mode growth and rotation, and sub-peak structures reflecting the interplay between the magnetic island formed by the tearing mode, RE diffusion during island rotation and the geometry of obstacles in the vessel. Correlations between the Cherenkov signal, hard x-ray emission and electron cyclotron emission reveal the impulsive development of the anomalous Doppler instability with instability rise time in the microsecond scale resolved by the high time-resolution of the Cherenkov probe.

Nuclear fusion 59 (4), pp. 046013-1–046013-13

Keywords

plasma instabilities, Cherenkov probe, runaway electrons

CNR authors

Fanale Francesco, Baiocchi Benedetta, Lazzaro Enzo, Grosso Giovanni Maria, Tartari Umberto, Lontano Maurizio Giuseppe, De Angeli Marco, Sozzi Carlo, Farina Daniela, Granucci Gustavo, Garavaglia Saul Francesco, Bin William Maurizio, Figini Lorenzo, Moro Alessandro Andrea, Mellera Vittoria Antonia, Nowak Silvana, Laguardia Laura, Ricci Daria, Alessi Edoardo, Puiatti Maria Ester, Causa Federica, Minelli Daniele, Simonetto Alessandro, Valisa Marco, Bruschi Alessandro, Carraro Lorella

CNR institutes

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