Transport by intermittency in the boundary of the DIII-D tokamak

Intermittent plasma objects (IPOs), featuring higher pressure than the surrounding plasma, are responsible for similar to50% of the ExB(T) radial transport in the scrape off layer (SOL) of the Doublet III D (DIII-D) tokamak [J. L. Luxon, Nucl. Fusion 42, 614 (2002)] in L- and H-mode discharges. Conditional averaging reveals that the IPOs are positively charged and feature internal poloidal electric fields of up to 4000 V/m. The IPOs move radially with ExB(T)/B-2 velocities of similar to2600 m/s near the last closed flux surface (LCFS), and similar to330 m/s near the wall. The IPOs slow down as they shrink in size from 2 cm at the LCFS to 0.5 cm near the wall. The skewness (i.e., asymmetry of fluctuations from the average) of probe and beam emission spectroscopy data indicate IPO formation at or near the LCFS and the existence of positive and negative IPOs which move in opposite directions. The particle content of the IPOs at the LCFS is linearly dependent on the local density and decays over similar to3 cm into the SOL while their temperature decays much faster (similar to1 cm). (C) 2003 American Institute of Physics.