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Integrated Modelling with COCONUT of Type‐I ELMs at JET
Author(s) -
Wiesen S.,
Parail V.,
Corrigan G.,
Fundamenski W.,
Loarte A.,
Lönnroth J.,
Saibene G.,
Sartori R.
Publication year - 2008
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.200810036
Subject(s) - pedestal , plasma , tokamak , jet (fluid) , mechanics , pressure gradient , physics , magnetohydrodynamics , convection , divertor , atomic physics , instability , atmospheric pressure plasma , computational physics , materials science , nuclear physics , archaeology , history
When modelling ELMy H‐mode plasmas the strong interaction between the core plasma and the scrape‐offlayer (SOL) must be accounted for. The 1.5D core code JETTO [1] and the 2D SOL fluid‐code EDGE2D [2] have been combined to provide a consistent picture of the transport across the separatrix, resulted in the coupled code COCONUT [3]. The ELM‐crash itself is modelled in an ad hoc manner, by which the perpendicular diffusive transport within the ETB is enhanced for a short time (≈ few 100 μs). An ELM is triggered if the normalised pressure gradient exceeds a critical threshold, α c , specified by the MHD‐stability analysis [4]. COCONUT simulations indicate that the neutral penetration changes the ETB transport behaviour qualitatively such as it reduces convection [5]. But since the same power enters the ETB from the core, a reduction in the convected out.ux to the SOL leads to a peak in the radial pressure gradient profile earlier in the ELM cycle. As a consequence, the ELM frequency increases, a tendency which is indeed seen in experiment. This paper concentrates on the modelling of type‐I ELMy H‐mode, pure‐D JET plasmas, seeking to match experimental results for different scans of gas‐puff, pedestal parameters (such as n ped , T ped and ν * ped ). The effects on ELM frequency, power‐exhaust, a detailed analysis of the time‐dependence of ELM‐crashes and the reformation of the pedestal are discussed. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)