000229883 001__ 229883
000229883 005__ 20190517100519.0
000229883 022__ $$a1089-7674
000229883 02470 $$2ISI$$a000404639000038
000229883 0247_ $$a10.1063/1.4985075$$2doi
000229883 037__ $$aARTICLE
000229883 245__ $$aPoloidal asymmetry in the narrow heat flux feature in the TCV scrape-off layer
000229883 269__ $$a2017
000229883 260__ $$c2017
000229883 300__ $$a12
000229883 336__ $$aJournal Articles
000229883 520__ $$aHeat flux profiles inferred from a reciprocating probe at the outer midplane of the TCV tokamak during inner wall limited discharges feature radial fall-off lengths that shorten near the last closed flux surface (LCFS) consistent with the so-called narrow feature. The narrow feature is significantly wider on the outboard side compared with that measured on the inner wall by infrared thermography, so it is difficult to discern from the main scrape-off layer feature. After small shifts were applied for alignment, the fraction of the power contained in the narrow feature matches between inboard and outboard measurements, and they scale together with plasma current I-p, suggesting that we are observing the same phenomenon. The outboard side fall-off length within the narrow feature is found to scale closely with the radial correlation length of the edge turbulence as expected if the narrow feature arises due to radially sheared E x B flows. This is found to hold true even for cases where the narrow feature is weak and the fall-off lengths are approaching that of the far scrape-off layer. After the small shifts for alignment, non-zero floating potential profiles were found to match between inboard and outboard sides. A simple model of polarization and diamagnetic cross-field currents is described, which is consistent with the shape of these floating potential profiles. The model predicts that the floating potential at the LCFS must be negative, which supports the argument to shift the upstream measurements. The predicted currents are also consistent with the E x B flows believed to cause the narrow feature. The model is used to predict the magnitude of the floating potential of the LCFS, and the results are found to match measurements for all values of Ip. This paper therefore demonstrates consistency between the measurements of the narrow feature on the inboard and outboard sides of the plasma, as well as consistency between the measurements, non-linear turbulence simulations, and analytical models of the narrow feature arising from sheared E x B flows.
000229883 6531_ $$aCRPP_EDGE
000229883 700__ $$aTsui, C. K.
000229883 700__ $$aBoedo, J. A.
000229883 700__ $$aHalpern, F. D.
000229883 700__ $$aLoizu, J.
000229883 700__ $$aNespoli, F.
000229883 700__ $$aHoracek, J.
000229883 700__ $$aLabit, B.
000229883 700__ $$aMorales, J.
000229883 700__ $$aReimerdes, H.
000229883 700__ $$aRicci, P.
000229883 700__ $$g176719$$aTheiler, C.$$0240123
000229883 700__ $$aCoda, S.
000229883 700__ $$aDuval, B. P.
000229883 700__ $$aFurno, I
000229883 710__ $$aTCV Team; EUROfusion MST1 Team
000229883 773__ $$q062508$$k6$$j24$$tPhysics of Plasmas
000229883 8560_ $$fbenoit.labit@epfl.ch
000229883 909C0 $$0252028$$pSPC$$xU12272$$xU12268$$xU10558$$xU10635$$xU12266$$xU10636$$xU10137$$xU12270$$xU10557$$xU12273$$xU10559$$xU12271$$xU12269$$xU12267$$xU10136
000229883 909CO $$pSB$$particle$$ooai:infoscience.tind.io:229883
000229883 917Z8 $$x176621
000229883 937__ $$aEPFL-ARTICLE-229883
000229883 973__ $$rREVIEWED$$sPUBLISHED$$aEPFL
000229883 980__ $$aARTICLE