Interplay between edge magnetic topology, pressure profile and blobs in the edge of RFX-mod

• Published in: Plasma physics and controlled fusion 2012-06, Vol.54 (6), p.65003
• Main Authors: Agostini, M, Scaggion, A, Scarin, P, Spizzo, G, Vianello, N
• Format: Article
• Language: English
• ISSN: 0741-3335; 1361-6587
• DOI: 10.1088/0741-3335/54/6/065003

The observation of the periodic pressure profile time oscillations in the edge region (0.93 < r/a < 1) of a RFX-mod device allows one to investigate the role of pressure as a turbulence regulation mechanism. The proportionality between the radial correlation length of edge fluctuations and the radial characteristic pressure length Lp suggests a sort of regulation of the turbulent spatial scale, where Lp sets the radial dimension of the blobs. Moreover, the spatial scale regulation is confirmed by observing a linear scaling between the energy injection scale and the toroidal dimension of the edge coherent structures. On the other hand, the link between ∇Pe and turbulence level does not hold locally: the edge fluctuation level is higher in the toroidal region of lower edge pressure gradient. Hence if coherent structures are generated locally in the region of strongest ∇Pe, they flow and accumulate where ∇Pe is lower.