An interesting result of magnetic chaos reduction in RFX-mod high current discharges is the development of strong electron transport barriers. An internal heat and particle transport barrier is formed when a bifurcation process changes the magnetic configuration into a helical equilibrium and chaos reduction follows, together with the formation of a null in the q shear. Strong temperature gradients develop, corresponding to a decreased thermal and particle transport. Turbulence analysis shows that the large electron temperature gradients are limited by the onset of micro-tearing modes, in addition to residual magnetic chaos. A new type of electron transport barrier with strong temperature gradients develops more externally (r/a = 0.8) accompanied by a 30% improvement of the global confinement time. The mechanism responsible for the formation of such a barrier is still unknown but it is likely associated with a local reduction of magnetic chaos. These external barriers develop primarily in situations of well-conditioned walls so that they might be regarded as attempts towards an L-H transition. Both types of barriers occur in high-current low-collisionality regimes. Analogies with tokamak and stellarators are discussed. © 2011 IAEA, Vienna.

Puiatti, M., Valisa, M., Agostini, M., Auriemma, F., Bonomo, F., Carraro, L., et al. (2011). Internal and external electron transport barriers in the RFX-mod reversed field pinch. NUCLEAR FUSION, 51(7) [10.1088/0029-5515/51/7/073038].

Internal and external electron transport barriers in the RFX-mod reversed field pinch

Martines E;
2011

Abstract

An interesting result of magnetic chaos reduction in RFX-mod high current discharges is the development of strong electron transport barriers. An internal heat and particle transport barrier is formed when a bifurcation process changes the magnetic configuration into a helical equilibrium and chaos reduction follows, together with the formation of a null in the q shear. Strong temperature gradients develop, corresponding to a decreased thermal and particle transport. Turbulence analysis shows that the large electron temperature gradients are limited by the onset of micro-tearing modes, in addition to residual magnetic chaos. A new type of electron transport barrier with strong temperature gradients develops more externally (r/a = 0.8) accompanied by a 30% improvement of the global confinement time. The mechanism responsible for the formation of such a barrier is still unknown but it is likely associated with a local reduction of magnetic chaos. These external barriers develop primarily in situations of well-conditioned walls so that they might be regarded as attempts towards an L-H transition. Both types of barriers occur in high-current low-collisionality regimes. Analogies with tokamak and stellarators are discussed. © 2011 IAEA, Vienna.
Articolo in rivista - Articolo scientifico
reversed field pinch; RFP; RFX-mod; transport barriers;
English
9
Puiatti, M., Valisa, M., Agostini, M., Auriemma, F., Bonomo, F., Carraro, L., et al. (2011). Internal and external electron transport barriers in the RFX-mod reversed field pinch. NUCLEAR FUSION, 51(7) [10.1088/0029-5515/51/7/073038].
Puiatti, M; Valisa, M; Agostini, M; Auriemma, F; Bonomo, F; Carraro, L; Fassina, A; Gobbin, M; Lorenzini, R; Momo, B; Scaggion, A; Zaniol, B; Alfier, A; Apolloni, L; Baruzzo, M; Bolzonella, T; Bonfiglio, D; Canton, A; Cappello, S; Cavazzana, R; Dal Bello, S; De Masi, G; Escande, D; Franz, P; Gazza, E; Guo, S; Innocente, P; Marchiori, G; Marrelli, L; Martin, P; Martines, E; Martini, S; Menmuir, S; Novello, L; Paccagnella, R; Piovesan, P; Piron, L; Predebon, I; Ruzzon, A; Sattin, F; Scarin, P; Soppelsa, A; Spizzo, G; Spagnolo, S; Spolaore, M; Terranova, D; Veranda, M; Vianello, N; Zanca, P; Zanotto, L; Zuin, M
File in questo prodotto:
File Dimensione Formato  
114 - NF 11 transport barriers IAEA.pdf

Solo gestori archivio

Tipologia di allegato: Publisher’s Version (Version of Record, VoR)
Dimensione 1.39 MB
Formato Adobe PDF
1.39 MB Adobe PDF   Visualizza/Apri   Richiedi una copia

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/10281/354643
Citazioni
  • Scopus 29
  • ???jsp.display-item.citation.isi??? 22
Social impact