A spontaneous transition to a helical equilibrium with an electron internal transport barrier is observed in RFX-mod as the plasma current is raised above 1 MA (Lorenzini R et al 2009 Nature Phys. 5 570). The helical magnetic equilibrium can be controlled with external three-dimensional (3D) magnetic fields applied by 192 active coils, providing proper helical boundary conditions either rotating or static. The persistence of the helical equilibrium is strongly increased in this way. A slight reduction in the energy confinement time of about 15% is observed, likely due to the increased plasma-wall interaction associated with the finite radial magnetic field imposed at the edge. A global helical flow develops in these states and is expected to play a role in the helical self-organization. In particular, its shear may contribute to the ITB formation and is observed to increase with the externally applied radial field. The possible origins of this flow, from nonlinear visco-resistive magnetohydrodynamic (MHD) and/or ambipolar electric fields, will be discussed. © 2011 IOP Publishing Ltd.

Piovesan, P., Bonfiglio, D., Bonomo, F., Cappello, S., Carraro, L., Cavazzana, R., et al. (2011). Influence of external 3D magnetic fields on helical equilibrium and plasma flow in RFX-mod. PLASMA PHYSICS AND CONTROLLED FUSION, 53(8) [10.1088/0741-3335/53/8/084005].

Influence of external 3D magnetic fields on helical equilibrium and plasma flow in RFX-mod

Martines E;
2011

Abstract

A spontaneous transition to a helical equilibrium with an electron internal transport barrier is observed in RFX-mod as the plasma current is raised above 1 MA (Lorenzini R et al 2009 Nature Phys. 5 570). The helical magnetic equilibrium can be controlled with external three-dimensional (3D) magnetic fields applied by 192 active coils, providing proper helical boundary conditions either rotating or static. The persistence of the helical equilibrium is strongly increased in this way. A slight reduction in the energy confinement time of about 15% is observed, likely due to the increased plasma-wall interaction associated with the finite radial magnetic field imposed at the edge. A global helical flow develops in these states and is expected to play a role in the helical self-organization. In particular, its shear may contribute to the ITB formation and is observed to increase with the externally applied radial field. The possible origins of this flow, from nonlinear visco-resistive magnetohydrodynamic (MHD) and/or ambipolar electric fields, will be discussed. © 2011 IOP Publishing Ltd.
Articolo in rivista - Articolo scientifico
reversed field pinch; RFP; RFX-mod; quasi-single helicity; QSH;
English
14
Piovesan, P., Bonfiglio, D., Bonomo, F., Cappello, S., Carraro, L., Cavazzana, R., et al. (2011). Influence of external 3D magnetic fields on helical equilibrium and plasma flow in RFX-mod. PLASMA PHYSICS AND CONTROLLED FUSION, 53(8) [10.1088/0741-3335/53/8/084005].
Piovesan, P; Bonfiglio, D; Bonomo, F; Cappello, S; Carraro, L; Cavazzana, R; Gobbin, M; Marrelli, L; Martin, P; Martines, E; Momo, B; Piron, L; Puiatti, M; Soppelsa, A; Valisa, M; Zanca, P; Zaniol, B
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/10281/352373
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