Far SOL transport and main wall plasma interaction in DIII-D

Abstract

IAEA-CN-116/EX/P5-29 This is a preprint of a paper intended for presentation at a scientific meeting. Because of the provisional nature of its content and since changes of substance or detail may have to be made before publication, the preprint is made available on the understanding that it will not be cited in the literature or in any way be reproduced in its present form. The views expressed and the statements made remain the responsibility of the named author(s); the views do not necessarily reflect those of the government of the designating Member State(s) or of the designating organization(s). In particular, neither the IAEA nor any other organization or body sponsoring this meeting can be held responsible for any material reproduced in this preprint.

Convective transport by intermittent blob-filaments: Comparison of theory and experiment

“…54 Measurements of blob outward transport using conditional sampling are reported in many experiments (e.g., Refs. 18,19,24,125,126,144, and 169 while evidence for holes moving inward can be found in Refs. 126, 129, 130, 144, 158, 159, 169, and 180).…”

“…15,16 Blobs and ELM filaments can also carry heat across the SOL, possibly affecting the SOL width for parallel heat flow (spreading the heat load) and increasing the interaction with the far SOL. 24,25 Increased convective heat transport near the separatrix may also be correlated with the density limit in some tokamaks. [26][27][28][29] Finally, blob momentum transport may influence the edge velocity shear layer and thus the core plasma confinement, at least in L-mode plasmas.…”

“…While the physics of ELM generation is beyond the scope of this paper, it is important to point out that ELMs produce filaments of plasma that propagate across the far SOL in a manner similar to blobs 19,24,[32][33][34][35][36] (see also Sec. V B 2).…”

Physics of ultimate detachment of a tokamak divertor plasma

“…It is known for a long time that in L-mode, cross-field transport is increasing at high plasma density when approaching detachment (see e.g. Umansky et al 1998;LaBombard et al 2000;Greenwald 2002;Rudakov et al 2005;Wiesen et al 2011. Usually it is related to the increased contribution of intermittent blobby plasma transport (see Zweben et al 2007;Krasheninnikov et al 2008;D'Ippolito et al 2011, and the references therein).…”

Far scrape-off layer particle and heat fluxes in high density – High power scenarios

“…It is well known that in the far SOL of high density L-mode [2,3,4,5] and H-mode discharges [6] a broad density shoulder forms indicating a large cross-field transport. Previous investigations in L-mode revealed that the density wing formation is related to a change from a conductive to a convective transport regime [3] where also the outer divertor starts to detach and the turbulence characteristic is changing [7,8].…”