The modified RFX is a very flexible device used for a variety of control schemes for MHD instabilities and for advanced reverse field pinch scenarios. Relative to the previous machine, RFX-mod has a thin Cu shell with vertical field penetration time τS, lowered from 450 to 50 ms and shell/plasma proximity from b/a ≤ 1.24-1.1. Toroidal equilibrium is feedback-controlled and new power supplies provide better Bφ control. Newly designed graphite tiles protect the vessel from localized power deposition. A mesh of 192 external saddle coils, supervised by a digital feedback system, controls radial fields due to field errors and MHD modes. The paper presents an overview of the very encouraging results obtained using both new and 'standard' advanced operational modes in the current range 0.3-1 MA. A dramatic improvement of plasma performance was obtained by using the saddle coils to cancel all the radial field components, an operation mode dubbed virtual shell (VS). The toroidal voltage was lowered by more than 25% and the pulse length was tripled, up to 7 times the τS. Steady-state RFP pulses are now limited only by the applied volt-seconds. The improved magnetic boundary also has an effect on the tearing modes underlying the sustainment of the RFP, whose core amplitude is more than halved. The VS combined with new schemes for the active rotation of the MHD dynamo modes has allowed us to obtain reliable and well-controlled long RFP pulses in the MA current range. This results in a 100% increase in the particle and energy confinement time relative to the previous experiment and opens the possibility of exploring the machine performance in the 2 MA design range. © 2007 IAEA.

Martini, S., Agostini, M., Alessi, C., Alfier, A., Antoni, V., Apolloni, L., et al. (2007). Active MHD control at high currents in RFX-mod. NUCLEAR FUSION, 47(8), 783-791 [10.1088/0029-5515/47/8/008].

Active MHD control at high currents in RFX-mod

Martines E;
2007

Abstract

The modified RFX is a very flexible device used for a variety of control schemes for MHD instabilities and for advanced reverse field pinch scenarios. Relative to the previous machine, RFX-mod has a thin Cu shell with vertical field penetration time τS, lowered from 450 to 50 ms and shell/plasma proximity from b/a ≤ 1.24-1.1. Toroidal equilibrium is feedback-controlled and new power supplies provide better Bφ control. Newly designed graphite tiles protect the vessel from localized power deposition. A mesh of 192 external saddle coils, supervised by a digital feedback system, controls radial fields due to field errors and MHD modes. The paper presents an overview of the very encouraging results obtained using both new and 'standard' advanced operational modes in the current range 0.3-1 MA. A dramatic improvement of plasma performance was obtained by using the saddle coils to cancel all the radial field components, an operation mode dubbed virtual shell (VS). The toroidal voltage was lowered by more than 25% and the pulse length was tripled, up to 7 times the τS. Steady-state RFP pulses are now limited only by the applied volt-seconds. The improved magnetic boundary also has an effect on the tearing modes underlying the sustainment of the RFP, whose core amplitude is more than halved. The VS combined with new schemes for the active rotation of the MHD dynamo modes has allowed us to obtain reliable and well-controlled long RFP pulses in the MA current range. This results in a 100% increase in the particle and energy confinement time relative to the previous experiment and opens the possibility of exploring the machine performance in the 2 MA design range. © 2007 IAEA.
Articolo in rivista - Articolo scientifico
reversed field pinch; RFP; MHD control; RFX-mod;
English
783
791
9
Martini, S., Agostini, M., Alessi, C., Alfier, A., Antoni, V., Apolloni, L., et al. (2007). Active MHD control at high currents in RFX-mod. NUCLEAR FUSION, 47(8), 783-791 [10.1088/0029-5515/47/8/008].
Martini, S; Agostini, M; Alessi, C; Alfier, A; Antoni, V; Apolloni, L; Auriemma, F; Bettini, P; Bolzonella, T; Bonfiglio, D; Bonomo, F; Brombin, M; Buffa, A; Canton, A; Cappello, S; Carraro, L; Cavazzana, R; Cavinato, M; Chitarin, G; Cravotta, A; Dal Bello, S; De Lorenzi, A; De Pasqual, L; Escande, D; Fassina, A; Franz, P; Gadani, G; Gaio, E; Garzotti, L; Gazza, E; Giudicotti, L; Gnesotto, F; Gobbin, M; Grando, L; Guo, S; Innocente, P; Lorenzini, R; Luchetta, A; Malesani, G; Manduchi, G; Marchiori, G; Marcuzzi, D; Marrelli, L; Martin, P; Martines, E; Masiello, A; Milani, F; Moresco, M; Murari, A; Novello, L; Ortolani, S; Paccagnella, R; Pasqualotto, R; Peruzzo, S; Piovan, R; Piovesan, P; Pizzimenti, A; Pomaro, N; Puiatti, M; Rostagni, G; Sattin, F; Scarin, P; Serianni, G; Sonato, P; Spada, E; Soppelsa, A; Spizzo, G; Spolaore, M; Taccon, C; Taliercio, C; Terranova, D; Toigo, V; Valisa, M; Vianello, N; Zaccaria, P; Zanca, P; Zaniol, B; Zanotto, L; Zilli, E; Zollino, G; Zuin, M
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/10281/355938
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