EFDA-JET-CP(08)02/04
Intermittent Transport in the JET Far-SOL
The intermittent transport in the JET Scrape-Off Layer (SOL) has been investigated using a multi-pin reciprocating Langmuir probe system. ELMs are clearly observed to be composed of a number of coherent structures or filaments. These structures propagate radially with velocities up to 1km/s and lifetimes in the range 40-100ms. Radial transport in the far-SOL is not continuous but occurs in short bursts observed most often at the beginning of each structure. The magnitude of the parallel ion flux during the filaments quickly decreases with radius, contrary to the cross-field velocity which has a weak radial dependence. Data from the JET boundary plasma have been analyzed to characterize the properties of the intermittent events. Statistical analysis reveals that the filament duration is larger on average in L-mode when compared to that observed during ELMs, while the radial velocity and the density perturbations are smaller. Preprint of Paper to be submitted for publication in Proceedings of the 18th Plasma Surface Interactions in Controlled Fusion Devices Toledo, Spain ( 26th May 2008 - 30th May 2008)