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RITM‐Code Modelling of Plasmas with Edge Transport Barrier
Author(s) -
Kalupin D.,
Tokar M. Z.,
Unterberg B.,
Loozen X.,
Zagórski R.
Publication year - 2006
Publication title -
contributions to plasma physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.531
H-Index - 47
eISSN - 1521-3986
pISSN - 0863-1042
DOI - 10.1002/ctpp.200610064
Subject(s) - tokamak , divertor , plasma , limiter , materials science , convection , scaling , mechanics , atomic physics , physics , nuclear physics , geometry , electrical engineering , mathematics , engineering
Abstract Conditions for the formation of the edge transport barrier (ETB) in tokamaks are investigated by means of onedimensional 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 heat 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. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)