Post-disruption runaway electron (RE) beams in tokamaks with large current can cause deep melting of the vessel and are one of the major concerns for ITER operations. Consequently, a considerable effort is provided by the scientific community in order to test RE mitigation strategies. We present an overview of the results obtained at FTU and TCV controlling the current and position of RE beams to improve safety and repeatability of mitigation studies such as massive gas (MGI) and shattered pellet injections (SPI). We show that the proposed RE beam controller (REB-C) implemented at FTU and TCV is effective and that current reduction of the beam can be performed via the central solenoid reducing the energy of REs, providing an alternative/parallel mitigation strategy to MGI/SPI. Experimental results show that, meanwhile deuterium pellets injected on a fully formed RE beam are ablated but do not improve RE energy dissipation rate, heavy metals injected by a laser blow off system on low-density flat-top discharges with a high level of RE seeding seem to induce disruptions expelling REs. Instabilities during the RE beam plateau phase have shown to enhance losses of REs, expelled from the beam core. Then, with the aim of triggering instabilities to increase RE losses, an oscillating loop voltage has been tested on RE beam plateau phase at TCV revealing, for the first time, what seems to be a full conversion from runaway to ohmic current. We finally report progresses in the design of control strategies at JET in view of the incoming SPI mitigation experiments.

Carnevale, D., Ariola, M., Artaserse, G., Bagnato, F., Bin, W., Boncagni, L., et al. (2019). Runaway electron beam control. PLASMA PHYSICS AND CONTROLLED FUSION, 61(1), 014036 [10.1088/1361-6587/aaef53].

Runaway electron beam control

Carnevale, D.
;
Ferro, G.;Gabrielli, A.;Galeani, S.;Gospodarczyk, M.;Martinelli, F.;Possieri, C.;Sassano, M.;
2019

Abstract

Post-disruption runaway electron (RE) beams in tokamaks with large current can cause deep melting of the vessel and are one of the major concerns for ITER operations. Consequently, a considerable effort is provided by the scientific community in order to test RE mitigation strategies. We present an overview of the results obtained at FTU and TCV controlling the current and position of RE beams to improve safety and repeatability of mitigation studies such as massive gas (MGI) and shattered pellet injections (SPI). We show that the proposed RE beam controller (REB-C) implemented at FTU and TCV is effective and that current reduction of the beam can be performed via the central solenoid reducing the energy of REs, providing an alternative/parallel mitigation strategy to MGI/SPI. Experimental results show that, meanwhile deuterium pellets injected on a fully formed RE beam are ablated but do not improve RE energy dissipation rate, heavy metals injected by a laser blow off system on low-density flat-top discharges with a high level of RE seeding seem to induce disruptions expelling REs. Instabilities during the RE beam plateau phase have shown to enhance losses of REs, expelled from the beam core. Then, with the aim of triggering instabilities to increase RE losses, an oscillating loop voltage has been tested on RE beam plateau phase at TCV revealing, for the first time, what seems to be a full conversion from runaway to ohmic current. We finally report progresses in the design of control strategies at JET in view of the incoming SPI mitigation experiments.
Pubblicato
Rilevanza internazionale
Articolo
Esperti anonimi
Settore ING-INF/04 - Automatica
English
magnetic confinement; plasma control system; runaways; Nuclear Energy and Engineering; Condensed Matter Physics
http://iopscience.iop.org/article/10.1088/1361-6587/aaef53/pdf
Carnevale, D., Ariola, M., Artaserse, G., Bagnato, F., Bin, W., Boncagni, L., et al. (2019). Runaway electron beam control. PLASMA PHYSICS AND CONTROLLED FUSION, 61(1), 014036 [10.1088/1361-6587/aaef53].
Carnevale, D; Ariola, M; Artaserse, G; Bagnato, F; Bin, W; Boncagni, L; Bolzonella, T; Bombarda, F; Buratti, P; Calacci, L; Causa, F; Coda, S; Cordella, F; Decker, J; Tommasi, Gd; Duval, B; Esposito, B; Ferro, G; Ficker, O; Gabellieri, L; Gabrielli, A; Galeani, S; Galperti, C; Garavaglia, S; Havranek, A; Gobbin, M; Gospodarczyk, M; Granucci, G; Joffrin, E; Lennholm, M; Lier, A; Macusova, E; Martinelli, F; Martin-Solis, Jr; Mlynar, J; Panaccione, L; Papp, G; Passeri, M; Pautasso, G; Popovic, A; Possieri, C; Pucella, G; Sheikh, Ua; Ramogida, G; Reux, C; Rimini, F; Romano, A; Sassano, M; Tilia, B; Tudisco, O; Valcarcel, D
Articolo su rivista
File in questo prodotto:
Non ci sono file associati a questo prodotto.

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2108/211049
Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus 17
  • ???jsp.display-item.citation.isi??? 19
social impact