Comparison of the spatial and temporal structure of type-I ELMs

Kirk, A.*; Asakura, Nobuyuki; Boedo, J. A.*; Beurskens, M.*; Counsell, G. F.*; Eich, T.*; Fundamenski, W.*; Herrmann, A.*; Kamada, Yutaka; Leonard, A. W.*; Lisgo, S.*; Loarte, A.*; Oyama, Naoyuki; Pitts, R. A.*; Schmid, A.*; Wilson, H. R.*

A comparison of the spatial and temporal evolution of the filamentary structures observed during type I ELMs is presented from a variety of diagnostics and machines. There is evidence that these filaments can be detected inside the LCFS prior to ELMs. The filaments do not have a circular cross section instead they are elongated in the perpendicular (poloidal) direction and this size appears to increase linearly with the minor radius of the machine. The filaments start rotating toroidally/poloidally with velocities close to that of the pedestal. This velocity then decreases as the filaments propagate radially. It is most likely that the filaments have at least their initial radial velocity when they are far out into the SOL. The dominant loss mechanism is through parallel transport and the transport to the wall is through the radial propagation of these filaments. Measurements of the filament energy content show that each filament contains up to 2.5 % of the energy released by the ELM.