This title appears in the Scientific Report : 2006 

RITM-code modelling of plasmas with edge transport barrier
Kalupin, D.
Tokar, M. Z. / Unterberg, B. / Loozen, X. / Zagórski, R.
Institut für Plasmaphysik; IPP
Contributions to plasma physics, 46 (2006)
Weinheim Wiley-VCH 2006
10.1002/ctpp.200610064
Journal Article
Fusion
Contributions to Plasma Physics 46
J
ETB
Please use the identifier: http://dx.doi.org/10.1002/ctpp.200610064 in citations.
Conditions for the formation of the edge transport barrier (ETB) in tokamaks are investigated by means of one-dimensional transport modeling performed for the characteristic parameter range of the TEXTOR tokamak. The computations predict the formation of the ETB at the heating power given by the multi-machine scaling if the fraction of convective heat losses from the plasma does not exceed 50%. An increase of the amount of heat lost through convection above this critical value shifts the formation of ETB to a power several times above the level given by the scaling. For given plasma parameters, the ratio of the conductive to convective beat losses at the plasma edge is determined by the penetration of neutrals. By switching from a divertor to a limiter configuration when the distance between the LCMS and neutralizing plates decreases, this ratio increases due to the higher fraction of particles ionized inside the last closed magnetic surface (LCMS). This can be the reason for the higher H-mode power threshold in limiter tokamaks. First experimental results obtained in TEXTOR demonstrate a good agreement of the power required for ETB formation with the value calculated with 1.5D transport code RITM prior to the experiment. (c) 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.