Parallel expansion of density bursts

Guillaume Chiavassa (1) , Hugo Bufferand (1) , Guido Ciraolo (1) , Philippe Ghendrih (2) , Hervé Guillard (3) , Livia Isoardi (1) , A. Paredes (1) , Frédéric Schwander (1) , Eric Serre (1) , Patrick Tamain (2)

1 M2P2 - Laboratoire de Mécanique, Modélisation et Procédés Propres
2 IRFM - Institut de Recherche sur la Fusion par confinement Magnétique
3 PUMAS - Plasma, tUrbulence, Modeling, Approximation and Simulation

Evidence of poloidally localized cross-field transport in experiments and theoretical analysis of turbulence transport governs the onset of parallel transport towards equilibrium. When cross-field transport appears in bursts, both for ELM relaxation events and microturbulence, the parallel transport of particles is shown to generate fronts that propagate with supersonic velocities. It is shown that after a short transient the density structure is no longer monotonic and that the two fronts (one co, the other counter the magnetic field) are independent. Furthermore, the time trace of the particle flux at a given location is characterized by a sharp rise followed by a longer time scale relaxation. Comparing the time delay and magnitude of the density burst at two locations allows to estimate the magnitude and the location of the generation of the front.

Domaines: Mécanique des fluides [physics.class-ph]; Mécanique des fluides [physics.class-ph]

Guillaume Chiavassa, Hugo Bufferand, Guido Ciraolo, Philippe Ghendrih, Hervé Guillard, et al.. Parallel expansion of density bursts. Journal of Nuclear Materials, 2011, 415 (1), pp.S613-S616. ⟨10.1016/j.jnucmat.2010.10.086⟩. ⟨hal-00848522⟩